Details of a Researcher - NISHINO Koichi

Microgravity experiments on Marangoni convection in a liquid bridge of high-Prandtl-number fluid so-called Marangoni Experiment in Space (MEIS) and Dynamic Surf (DS) were performed on board the International Space Station (ISS) to understand the Marangoni convection instability. This study reports the internal flow patterns and velocity profiles of the axisymmetric steady Marangoni convection observed in these projects for various Prandtl numbers (Pr = 67, 112 and 207), and for various liquid bridge geometries. The classical three-dimensional particle tracking velocimetry (3-D PTV) is customized for the microgravity experiments, and the spatial structures of the Marangoni convection in liquid bridges are measured with good accuracy. The details of the measurement method currently used, and the results of the 3-D PTV are discussed in this study.

Other Link： https://ci.nii.ac.jp/naid/130007760923

Effect of radiative heat transfer on thermocapillary convection in long liquid bridges of high-Prandtl-number fluids in microgravity

Shitomi Nobuhiro, Yano Taishi, Nishino Koichi

INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER 133 405 - 415 2019.4

DOI Web of Science

Language：Japanese Publishing type：Research paper (scientific journal) Joint Work

Turbulence characteristics of radially-confined impinging jet flows

C Shekhar,K Nishino

International Journal of Heat and Fluid Flow 75 278 - 299 2019.2 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Effect of interfacial heat transfer on basic flow and instability in a high-Prandtl-number thermocapillary liquid bridge

T Yano, M Hirotani, K Nishino

International Journal of Heat and Mass Transfer 125 1121 - 1130 2018.10 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Convective mixing of miscible liquids in a rotor-stator spinning disk reactor

Hitoshi Toma and Koichi Nishino

Chemical Engineering Journal 346 329 - 339 2018.8 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Convective mixing of two miscible liquids injected into a rotor-stator spinning disk reactor (RS-SDR) has been
studied using an LIF technique and CFD simulations. The fluids are ammonia water and fluorescein ammonia
water solutions. The RS-SDR has a rotor 100mm in diameter and a thin circular cavity 0.10–0.15mm in height
between the rotor and stator. Laminar flow conditions for rotation speeds up to 120 rpm and total flow rates up
to 8 mL/min are considered. The fluorescein solution is injected from the second off-center hole into the cavity
filled with the ammonia water supplied from the central hole. The LIF technique visualizes a spiral streak pattern
formed downstream of the second injection hole. This streak pattern is analyzed to calculate the local mixedness
of the two fluids. It is determined that the mixedness increases for lower flow rates, while it is less sensitive to
rotation speed and cavity height. The CFD simulations indicate that the spiral streak pattern is deformed and
stretched in the radial direction to form a densely layered structure of the two fluids. The development of the
mixedness along the streak pattern is correlated well with Reinlet/Recavity, where Reinlet and Recavity are the Reynolds
numbers for the injected flow and the azimuthal flow in the cavity, respectively. This Reynolds number ratio is
shown to be related to the Rossby number and the position and radius of the second injection hole. The proposed
correlation is based on a linear combination of injection mixing and rotation mixing. The mixedness decreases
with Reinlet/Recavity because the injection mixing decreases with Reinlet while the rotation mixing increases with
Recavity.

Other Link： https://www.sciencedirect.com/science/article/pii/S1385894718305655

Terrestrial and microgravity experiments on onset of oscillatory thermocapillary-driven convection in hanging droplets

International Journal of Heat and Mass Transfer 123 945 - 9556 2018.8 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Other Link： https://www.sciencedirect.com/science/article/pii/S0017931018308652?via%3Dihub

Report on Microgravity Experiments of Dynamic Surface Deformation Effects on Marangoni Instability in High-Prandtl-Number Liquid Bridges

Taishi Yano, Koichi Nishino, Satoshi Matsumoto, Ichiro Ueno, Atsuki Komiya, Yasuhiro Kamotani and N … Show more authors

Microgravity Science and Technology 2018.4 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Joint Work

This paper reports an overview and some important results of microgravity experiments called Dynamic Surf, which have
been conducted on board the International Space Station from 2013 to 2016. The present project mainly focuses on the
relations between the Marangoni instability in a high-Prandtl-number (Pr = 67 and 112) liquid bridge and the dynamic free
surface deformation (DSD) as well as the interfacial heat transfer. The dynamic free surface deformations of large-scale
liquid bridges (say, for diameters greater than 10 mm) are measured with good accuracy by an optical imaging technique. It
is found that there are two causes of the dynamic free surface deformation in the present study: the first is the time-dependent
flow behavior inside the liquid bridge due to the Marangoni instability, and the second is the external disturbance due to the
residual acceleration of gravity, i.e., g-jitter. The axial distributions of DSD along the free surface are measured for several
conditions. The critical parameters for the onset of oscillatory Marangoni convection are also measured for various aspect
ratios (i.e., relative height to the diameter) of the liquid bridge and various thermal boundary conditions. The characteristics
of DSD and the onset conditions of instability are discussed in this paper.

Other Link： https://link.springer.com/article/10.1007/s12217-018-9614-9

Overview of “Dynamic Surf” Project in Kibo–Dynamic Behavior of Large-Scale Thermocapillary Liquid Bridges in Microgravity

Taishi YANO, Koichi NISHINO, Satoshi MATSUMOTO, Ichiro UENO, Atsuki KOMIYA, Yasuhiro KAMOTANI and N … Show more authors

International Journal of Microgravity Science and Application 35 ( 1 ) 23456 - 1 - 23456-7 2018.4 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Microgravity Application Joint Work

This paper reports the overview of Dynamic Surf project conducted in the Japanese Experiment Module Kibo on board the International Space
Station (ISS), especially focusing on the experimental conditions, the measurement systems, and the g-jitter effects. Oscillatory Marangoni
convection in the liquid bridge is associated with oscillatory motion of the liquid-gas interface due to velocity oscillation inside the liquid bridge,
where such a motion is called dynamic surface deformation (DSD). The present project aims at understanding the DSD effect in the transition
mechanisms of temperature gradient-driven Marangoni convection in large-scale liquid bridges of high-Prandtl-number fluids through the longterm
microgravity experiments on board the ISS. A series of microgravity experiments have been conducted in the period from September 2013
to November 2016 to understand the instability mechanisms and the role of DSD in Marangoni convection.

Other Link： http://www.jasma.info/journal/wp-content/uploads/sites/2/2018/01/2018_p350102.pdf

Sensitivity of hydrothermal wave instability of Marangoni convection to the interfacial heat transfer in long liquid bridges of high Prandtl number fluids

29 ( 044105 ) 044105 - 1 - 044105-11 2017.3 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Other Link： http://aip.scitation.org/doi/10.1063/1.4979721

Effect of ambient gas flow on the instability of Marangoni convection in liquid bridges of various volume ratios

International Journal of Heat and Mass Transfer 99 182 - 191 2016.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Instability of Marangoni convection in liquid bridges (LBs) of high Prandtl number (Pr) fluids has been studied by focusing on the effect of ambient gas flow on the LBs of various volume ratios. The working fluids are 2 cSt (Pr = 28 ) and 5 cSt (Pr = 67) silicone oils. The LB is suspended in a gap between the upper heating rod and the lower cooling rod and it is surrounded by a coaxial cylindrical wall to form an annular passage between the LB and the inner wall surface. The ambient gas motion is given to this annular passage in the range from -35 mm/s (vertically downward) to +35 mm/s (vertically upward). The ratio of the LB volume to the gap volume is varied from 0.80 (slender LB) to 1.10 (slightly fat LB). The critical temperature differences for the onset of instability are measured and corresponding critical Marangoni numbers are determined. Numerical computations are carried out to understand the flow and temperature fields both in the LB and in the ambient gas at each measured critical temperature difference. The computation results are used to evaluate the convective and the radiative heat transfers from the LB. The effect of the ambient gas motion on the relationship between the critical Marangoni number and the volume ratio is revealed. The effect is discussed in terms of the Biot number defined using the heat transfer and the critical temperature difference. It is shown that the Biot number increases with the ambient gas velocity for slender LBs while it is nearly constant for slightly fat LBs. It is found that the critical Marangoni numbers plotted as a function of the Biot number for various volume ratios and ambient gas velocities fall on a single profile corresponding to each Pr. Such a behavior is shown to be in accord with the previous data taken under various ambient gas temperatures and cooling rod temperatures.

Other Link： http://www.sciencedirect.com/science/article/pii/S0017931015307298

Study on cycle-to-cycle flows in a motored engine - validation of LES through comparison with PIV measurement -

Ryuusaku Sawada, Ryuji Koike and Koichi Nishino

JSAE Transaction 47 ( 3 ) 711 - 716 2016.5 [Reviewed]

DOI

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Society of Automotive Engineers of Japan Joint Work

Cycle-to-cycle variations (CCVs) in internal combustion engines are caused by the combustion variations whose origin and mechanisms are not yet fully understood. The present study focuses on the CCVs of in-cylinder flows in a specially-designed motored engine that allows direct comparison between PIV measurement and CFD. Inflow conditions at the straight entrance section upstream of the intake ports are carefully measured and shown to have substantially no CCVs in pressure and velocity. Those conditions are faithfully reproduced in the present CFD using LES and RANS, where the latter is carried out to provide phase-averaged results. The PIV measurement shows the presence of CCVs of considerable magnitude in the intake stroke, which consequently leads to appreciable CCVs of swirl ratio and tumble ration even in the compression stroke. These features are successfully captured by the present LES.

Other Link： https://www.bookpark.ne.jp/cm/jsae/search.asp

Transition to chaotic thermocapillary convection in a half zone liquid bridge

Taiki Matsugasea, Ichiro Ueno, Koichi Nishino, Mitsuru Ohnishi, Masato Sakurai, Satoshi Matsumoto, … Show more authors

International Journal of Heat and Mass Transfer 89 903 - 912 2015.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

A series of fluid physics microgravity experiments with an enough long run time were performed in the 'KIBO,' the Japanese Experiment Module aboard the International Space Station, to examine the transition to chaos of the thermocapillary convection in a half zone liquid bridge of silicone oil with a Prandtl number of 112. The temperature difference between the coaxial disks induced the thermocapillary-driven flow, and we experimentally demonstrated that the flow fields underwent a transition from steady flow to oscillatory flow, and finally to chaotic flow with increasing temperature difference. We obtained the surface temperature time series at the middle of the liquid bridge to quantitatively evaluate the transition process of the flow fields. By Fourier analysis, we further confirmed that the flow fields changed from a periodic, to a quasi-periodic, and finally to a chaotic state. The increasing nonlinearity with the development of the flow fields was confirmed by time-series chaos analysis. The determined Lyapunov exponent and the translation error indicated that the flow fields made transition to the chaotic field with the increasing temperature difference.

Other Link： http://www.sciencedirect.com/science/article/pii/S0017931015005323

Modeling of the experiments on the Marangoni convection in liquid bridges in weightlessness for a wide range of aspect ratio

the International Journal of Heat and Mass Transfer 87 119 - 127 2015.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

Hydrodynamic stability of a two-dimensional steady thermocapillary flow under weightlessness in a high-Prandtl number liquid bridge is studied by means of three-dimensional numerical modeling for a wide range of aspect ratios. We suggest an explanation of the findings of a series of microgravity experiments on Marangoni convection in liquid bridges. Stability of the flow with heat transfer through the interface, modeled by the classical Fourier law, is compared with the stability of the same system under adiabatic conditions. Cooling the interface may significantly shift the threshold of hydrothermal instability as soon as the Biot number deviates from zero. It may also affect the structure of the basic Marangoni flow and the mode of the supercritical flow. We demonstrate that the heat loss has a destabilizing effect for the aspect ratios (ratio of radius to height) below 2.4 (with the exception of a region between 1.6 and 1.8), and for the longer liquid bridges the prevailing effect is stabilizing. The heat transfer coefficient as a function of the length of the liquid zone is theoretically calculated using a model of heat transport for laminar forced convection. Comparison of the results of the modeling with the experimental data shows that an incorrect assessment of the heat transfer may lead to wrong conclusions concerning both the critical parameters of the flow and its structure.

Other Link： http://www.sciencedirect.com/science/article/pii/S0017931015002744#

Effect of liquid bridge shape on the oscillatory thermal Marangoni convection

The European Physical Journal Special Topics 224 ( 2 ) 289 - 298 2015.4 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER Joint Work

The effect of liquid bridge shape on the instability and associated oscillation mode of Marangoni convection due to the temperature gradient along the free surface is experimentally studied. Although the onset condition of oscillatory state is known to depend on the liquid bridge shape, this effect is not completely understood yet. Onset conditions are measured for various combinations of the aspect ratio (AR) and the volume ratio (VR) of liquid bridges. It is found that the convection becomes most stabilized at a certain combination of AR and VR and also that the oscillation mode changes at this most stabilized condition. To account for the effects of AR and VR in a simple way, a new dimensionless parameter SDR (i.e., the ratio of the surface length to the neck diameter) is proposed. It is shown that all the onset conditions measured presently are well correlated with SDR.

Other Link： http://link.springer.com/article/10.1140/epjst/e2015-02360-8

Instability of thermocapillary convection in long liquid bridges of high Prandtl number fluids in microgravity

Journal of Crystal Growth 420 57 - 63 2015.3 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier Joint Work

This paper reports experimental results on the instability of thermocapillary convection in long half-zone liquid bridges of high Prandtl number fluids (Pr=67, 112 and 207 for 5, 10 and 20 cSt silicone oils, respectively). The experiments were carried out in microgravity on the International Space Station, which allowed sufficiently long waiting period for the development of instability. Critical temperature differences were measured for liquid bridges of 30 and 50 mm diameters and up to 62.5 mm length. The resultant critical Marangoni numbers (Mac) were obtained for a wide range of aspect ratio (=height/diameter), AR, up to AR=2.0. Linear stability analyses for Pr=67 were also carried out to obtain numerical data for comparison. The present experimental results for Pr=67 indicate 5.0 103 Mac 2.0 104 for large AR (AR 1.25) and they are in good agreement with the present linear stability analysis result. In contrast, the present results are considerably smaller than the previous data (Pr=74) taken in the Space Shuttle experiments. It is shown that this difference is due to the effect of heating rate of the liquid bridge. The data for oscillation frequency and azimuthal mode number are also presented. The non-dimensional oscillation frequencies as well as Mac for Pr=67 have shown a sudden decrease at around AR=1.25, suggesting the bifurcation of neutral stability curves.

Other Link： http://www.sciencedirect.com/science/article/pii/S0022024815002353

Instability and associated roll structure of Marangoni convection in high Prandtl number liquid bridge with large aspect ratio

Physics of Fluids 27 ( 2 ) 024108 - 1 - 024108-13 2015.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：AIP Publishing Joint Work

This paper reports the experimental results on the instability and associated roll structures (RSs) of Marangoni convection in liquid bridges formed under the microgravity environment on the International Space Station. The geometry of interest is high aspect ratio (AR = height/diameter > 1.0) liquid bridges of high Prandtl number fluids (Pr = 67 and 207) suspended between coaxial disks heated differentially. The unsteady flow field and associated RSs were revealed with the three-dimensional particle tracking velocimetry. It is found that the flow field after the onset of instability exhibits oscillations with azimuthal mode number m = 1 and associated RSs traveling in the axial direction. The RSs travel in the same direction as the surface flow (co-flow direction) for 1.00 < AR < 1.25 while they travel in the opposite direction (counterflow direction) for AR > 1.50, thus showing the change of traveling directions with AR. This traveling direction for AR > 1.50 is reversed to the co-flow direction when the temperature difference between the disks is increased to the condition far beyond the critical one. This change of traveling directions is accompanied by the increase of the oscillation frequency. The characteristics of the RSs for AR > 1.50, such as the azimuthal mode of oscillation, the dimensionless oscillation frequency, and the traveling direction, are in reasonable agreement with those of the previous sounding rocket experiment for AR = 2.50 and those of the linear stability analysis of an infinite liquid bridge.

Other Link： http://scitation.aip.org/content/aip/journal/pof2/27/2/10.1063/1.4908042

Oscillation and heat transfer in upward laminar impinging jet flows

50 316–329 2014.12 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Upward, laminar, axisymmetric, pipe-issued, submerged impinging jets, with the water as the working fluid, are numerically investigated. The impingement surface is subjected to heating, which causes the wall jet to prematurely separate from the impingement surface and turns the following region into a dead zone where the heat transfer rate deteriorates. Effects of (1) the inlet-based Reynolds number, (2) the heating-rate dependent Grashof number, and (3) the impingement-surface height to the inlet-diameter ratio are examined in detail. It is found that the separated jet oscillates when the Richardson number of the flow is moderate, but it separates without any oscillation when the Richardson number is large. The flow oscillation also induces cyclic fluctuations in on-surface quantities, such as, the Nusselt number, the surface temperature, and the skin-friction coefficient. The flows slowly approach to statistically steady states where oscillation parameters and heat transfer properties tend to stabilize about fixed values.

Other Link： http://www.sciencedirect.com/science/article/pii/S0142727X14001076

粒子画像流速測定法と渦運動エネルギーを用いた回転水槽実験で発生する傾圧不安定波の定量化

筆保弘徳, 舛田あゆみ, 乙部直人, 熊澤里枝, 西野耕一

ながれマルチメディア 33 ( 6 ) 549 - 550 2014.10 [Reviewed]

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：一般社団法人日本流体力学会 Joint Work

回転水槽実験に発生する傾圧不安定波を対象として、水面の運動を粒子画像流速計（PIV）を用いて計測した結果をまとめたもの。水面の運動を平均場と渦度場のエネルギーに分解し、後者にフーリエ解析を適用して波数別渦運動エネルギーを算出することによって、傾圧不安定波の定量的は同定を行った。

Other Link： http://www.nagare.or.jp/publication/mm/archive/2014.html

The JEREMI-project on thermocapillary convection in liquid bridges. Part B: overview on impact of co-axial gas flow

10 ( 2 ) 197 - 240 2014 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Joint Work

Pure surface-tension-driven flow is a unique type of flow that can be controlled through external manipulation of thermal and/or mechanical boundary conditions at the free liquid surface where the entire driving force for the convection is generated. This unique feature has been exploited in recent studies for the active control of the flow instability. The use of forced coaxial gas streams has been proposed as a way to stabilize the Marangoni convection in liquid bridges in the planned space experiment JEREMI (Japanese and European Research Experiment on Marangoni Instabilities). It is aimed at understanding the mechanism of the instability and the role of the surface heat transfer and surface shear stresses. This overview presents corresponding preparatory experimental and numerical studies.

Other Link： http://www.techscience.com/doi/10.3970/fdmp.2014.010.197.html

Swirl-inducing inlet for passive micromixers

Takuya Matsunaga and Koichi Nishino

4 ( 2 ) 824 - 829 2013.11 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Semi-Lagrangian method for numerical analysis of fluid mixing in T-shaped micromixer

Takuya Matsunaga and Koichi Nishino

46 ( 10 ) 699 - 708 2013.10 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Numerical simulation of heat transfer coefficient and film-cooling performance influenced by the orientation of internal

Yukiko AGATA, Toshihiko TAKAHASHI, Eiji SAKAI, Koichi NISHINO

8 ( 3 ) 488 - 503 2013.9 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Other Link： https://www.jstage.jst.go.jp/article/jtst/8/3/8_488/_article

Hydrothermal wave instability in a high-aspect-ratio liquid bridge of Pr > 200 - on-orbit experiments in the Japanese Experiment Module 'Kibo' aboard the International Space Station

Fumihiko Sato, Ichiro Ueno, Hiroshi Kawamura, Koichi Nishino, Satoshi Matsumoto, Mitsuru Ohnishi, M … Show more authors

25 ( 1 ) 43 - 58 2013.2 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

The long-duration fluid physics experiments on a thermocapillary-driven flow have been carried out on the Japanese Experiment Module `Kibo' aboard the International Space Station (ISS) since 2008. In these experiments, various aspects of thermocapillary convection in a half-zone (HZ) liquid bridge of high Prandtl number fluid have been examined under the advantages of the long-duration high-quality microgravity environment. In 2010, the authors succeeded to realize nonlinear convective fields in the HZ liquid bridge of rather high aspect ratio. Special attention was paid on to the complex convective fields, especially on the behaviors of the hydrothermal wave (HTW) over the free surface visualized by an infrared camera. In order to evaluate the characteristics of the nonlinear convective behaviors and their transition processes, the authors indicate the images taken by the infrared camera describing the time evolution of HTW, the spatio-temporal diagram, the Fourier analysis, and the pseudo-phase space, reconstructed from the time series of the scalar information of the liquid bridge, that is, surface temperature variation. In this paper, the authors introduce the signature of complex HTW behaviors observed at the long-duration on-orbit experiments, and make comparisons with some previous terrestrial and microgravity experiments.

Other Link： http://link.springer.com/article/10.1007%2Fs12217-012-9332-7#

Effect of Orientation of Internal Turbulence Promoting Ribs on Flow Characteristics for Film Cooling

8 ( 1 ) 15 - 27 2013.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Numerical simulations have been performed to study the film cooling of a flat plate that has an internal cooling passage perpendicular to the main flow. The goal is to understand the effect of the orientation of turbulence promoting ribs installed in the internal cooling passage on the adiabatic film cooling effectiveness in the external main flow downstream of the cooling-air injection. Detached Eddy Simulation is carried out for the flow characteristics for two rib orientations at two blowing ratios. The simulation results have revealed that the rib orientation affects significantly the temperature and flow structures downstream of the cooling hole and therefore affects the film-cooling performance on the surface. The revealed difference is due to the presence/absence of intense spiral motion at the cooling-hole outlet and such a difference originates from an interaction between the flow separation behind the inclined rib and the flow suction at the inlet of inclined cooling hole. The simulation results are exploited to draw a clear picture for the fluid-dynamical mechanisms responsible for the effect of the rib orientation.

Other Link： https://www.jstage.jst.go.jp/article/jtst/8/1/8_15/_article/-char/ja/

An approach for accurate simulation of liquid mixing in a T-shaped micromixer

Takuya Matsunaga, Ho-Joon Lee and Koichi Nishino

Lab on a Chip 13 ( 8 ) 1515 - 1521 2013.1 [Reviewed]

DOI Web of Science PubMed

Language：English Publishing type：Research paper (scientific journal) Joint Work

particles for convective fluid mixing and posterior solving of a model of the species equation for molecular diffusion. The examined parameter range is Re = 1.33 x 10-2 to 240 at Sc = 3600. The proposed method is shown to simulate well the mixing quality even in the engulfment regime, where the ordinary grid-based simulation is not able to obtain accurate solutions with affordable mesh sizes due to the numerical diffusion at high Sc. The obtained results agree well with a backward random-walk Monte Carlo simulation, by which the accuracy of the proposed method is verified. For further investigation of the characteristics of the proposed method, the Sc dependency is examined in a wide range of Sc from 10 to 3600 at Re = 200. The study reveals that the model discrepancy error emerges more significantly in the concentration distribution at lower Sc, while the resulting mixing quality is accurate over the entire range.
In this paper, we propose a new computational method for efficient evaluation of the fluid mixing behaviour in a T-shaped micromixer with a rectangular cross section at high Schmidt number under steady state conditions. Our approach enables a low-cost high-quality simulation based on tracking of fluid

Other Link： http://pubs.rsc.org/en/content/articlelanding/2013/LC/c3lc41009a#!divAbstract

Stereo-PIV measurement of turbulence characteristics in a flow mixer

Shekhar Chandra, Nishino Koichi, Yamane Yoshiyuki, Huang Jian

Journal of Visualization 15 ( 4 ) 293 - 308 2012.11 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Three-component, turbulent flow measurements are performed using stereo PIV technique, in a cylindrical, stirred, water-flow mixer, with commercially available HR-100 as the impeller, which has three identical blades, separated by 120° with each other. The flow is analyzed at twelve axisymmetric, vertical planes, with the regular angular interval of 10°, so that the 12 planes cover the whole 120° separation between any two of the impeller blades. The results show that the turbulence mixing below the impeller is much higher than that above it, as the bulk fluid motion convects down the turbulence produced at the blade–water interfaces. Moreover, vortices with high level of turbulence, overwhelmingly dominated by the tangential velocity fluctuations, are created near the tips of the blades and convected downward, with their turbulence gradually dissipating with time. When these vortices are connected throughout the domain, they constitute three disconnected, helical arcs, each of which is connected to the tip of a blade and extends downward in the opposite direction to the rotation of the impeller. The arcs rotate with the same angular velocity of the impeller. The mean velocity and turbulence statistics of the flow are discussed at each of the alternate measurement planes.

3-D PTV measurement of Marangoni convection in liquid bridge in space experiment

Yano Taishi, Nishino Koichi, Kawamura Hiroshi, Ueno Ichiro, Matsumoto Satoshi, Ohnishi Mitsuru, Sak … Show more authors

Experiments in Fluids 53 ( 1 ) 9 - 20 2012.7 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Microgravity experiments have been conducted on the International Space Station in order to clarify the transition processes of the Marangoni convection in liquid bridges of high Prandtl number fluid. The use of microgravity allows us to generate large liquid bridges, 30 mm in diameter and up to 60 mm in length. Three-dimensional particle tracking velocimetry (3-D PTV) is used to reveal complex flow patterns that appear after the transition of the flow field to oscillatory states. It is found that a standing-wave oscillation having an azimuthal mode number equal to one appears in the long liquid bridges. For the liquid bridge 45 mm in length, the oscillation of the flow field is observed in a meridional plane of the liquid bridge, and the flow field exhibits the presence of multiple vortical structures traveling from the heated disk toward the cooled disk. Such flow behaviors are shown to be associated with the propagation of surface temperature fluctuations visualized with an IR camera. These results indicate that the oscillation of the flow and temperature field is due to the propagation of the hydrothermal waves. Their characteristics are discussed in comparison with some previous results with long liquid bridges. It is shown that the axial wavelength of the hydrothermal wave observed presently is comparable to the length of the liquid bridge and that this result disagrees with the previous linear stability analysis for an infinitely long liquid bridge.

Measurements of gas/oil free surface deformation caused by parallel gas flow

Matsunaga T., Mialdun A., Nishino K., Shevtsova V.

Physics of Fluids 24 ( 6 ) 062101 2012.6 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Flow-induced dynamic free-surface deformations are experimentally studied in a confined liquid volume of 5cSt silicone oil (Prandtl number Pr = 68). The geometry of the problem is a liquid column concentrically surrounded by an annular gas channel. A gas stream entering the duct from the top or bottom entrains the motionless liquid. The dynamic deformation of the gas–liquid interface is caused by a steady axisymmetric shear-driven flow. The experiments are performed in normal gravity conditions and the static deformation of a liquid bridge interface is unavoidable. The magnitude and shape of the dynamic surface deformation are analyzed using optical measurements with a comprehensive treatment of the images. The deviation of the free surface shape from the corresponding equilibrium profile is determined with an uncertainty of about 0.1 μm. The order of magnitude of the interface deformation is proportional to the capillary number, which is defined as the ratio of the viscous force per unit area to the capillary pressure. The study is performed for a large range of volumes and aspect ratios as well as for different gas velocities. As a general trend, the dynamic deformation grows with the gas velocity, which plays the role of a driving force, but a linear dependence is not observed for all volume ratios, despite the small Reynolds numbers, 280 < Reg < 560. The dynamic deformation displays a strong dependence on the liquid volume ratio and the direction of the gas stream parallel to the interface. When the gas flow is directed against gravity, the largest interface deformations are observed at the smallest volumes among the analyzed ones. In contrast, when the gas stream is aligned with gravity, then the deformations decrease with a decrease in the volume ratio, at a certain value attaining zero (vanishing) and then changing sign.

Report on Microgravity Experiments of Marangoni Convection Aboard International Space Station

Kawamura Hiroshi, Nishino Koichi, Matsumoto Satoshi, Ueno Ichiro

134 ( 3 ) 031005 2012.1 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Micro-PIV measurement and CFD analysis of a thin liquid flow between rotating and stationary disks

Lee, HJ., Nishino, K.

Journal of Visualization 14 249 - 258 2011.8 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer-Verlag Joint Work

A strongly sheared flow in a thin liquid layer between rotating and stationary disks is studied experimentally and numerically to clarify the characteristics of the flow in rotation-shearing chemical reactors. The disk diameter is 10 mm and the separation between the disks is 500 μm. The rotational speeds that are examined are 300, 500 and 700 rpm. The micro-PIV technique is used to measure the velocity in the liquid layer. A commercial CFD software is also used to obtain the results for the comparison and validation purposes. The overall velocity distributions revealed by the micro-PIV measurement are in good agreement with the CFD results. Both results show some interesting characteristics of the flow field, including the presence of a secondary flow and its influence on the tangential velocity profiles. The near-wall measurement in the micro-PIV technique is appreciably improved by the use of a simple digital, high-pass filtering technique that is applied to the acquired particle images. It is found that the flow characteristics in the thin liquid layer can be evaluated efficiently if the micro-PIV technique is used together with the high-pass filtering technique that is examined here.

Other Link： https://link.springer.com/article/10.1007/s12650-011-0082-1

Heat Induced Separation in Upward Impinging Jet Flows Experimental Verification and Underlying Mechanism

Shekhar Chandra, Nishino Koichi

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY 6 ( 1 ) 93 - 110 2011 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Space experiment on the instability of Marangoni convection in large liquid bridge - MEIS-4: effect of Prandtl number -

T Yano, K Nishino, H Kawamura, I Ueno, S Matsumoto, M Ohnishi, M Sakurai

Journal ofPhysics:ConferenceSeries 327 ( 012029 ) 1 - 7 2011 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：IOP Publishing Joint Work

Microgravity experiments on the thermocapillary convection in liquid bridge, called Marangoni Experiment in Space (MEIS), are carried out in "KIBO" of ISS. Three series of experiments, MEIS-1, 2, and 4, have been conducted so far. This paper reports the results obtained from MEIS-4, in which 20cSt silicone oil (Pr = 207) is used to generate large liquid bridges. They are suspended between coaxial disks that are 50mm in diameter, with their maximum length equal to 62.5mm. MEIS-4 aims at (1) determining the critical temperature difference for the onset of oscillatory flow; (2) realizing high Marangoni number conditions for high Pr fluid; (3) clarifying the effects of volume ratio, heating rate, hysteresis, and cooled disk temperature; and (4) observing whether the hydrothermal wave with azimuthal mode number m = 0 appears or not. The main results are presented and compared with those obtained in MEIS-1 and 2, which utilized liquid bridges of 5cSt silicone oil (Pr = 67).

Other Link： https://iopscience.iop.org/article/10.1088/1742-6596/327/1/012029

3-D Flow Measurement of Oscillatory Thermocapillary Convection in Liquid Bridge in MEIS

Taishi YANO, Koichi NISHINO, Hiroshi KAWAMURA, Ichiro UENO, Satoshi MATSUMOTO, Mitsuru OHNISHI, Shi … Show more authors

International Journal of Microgravity Science and Application 28 ( 2 ) S126 - S131 2011 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japan Society of Microgravity Application Joint Work

Marangoni Experiment in Space (MEIS) has been conducted in the International Space Station (ISS) in order to clarify the transition processes of thermocapillary convection in liquid bridges. The use of microgravity allows us to generate long liquid bridges, 30mm in diameter and up to 60mm in length. Several flow visualization techniques have been applied to those large liquid bridges. 3-D PTV is used to reveal highly three-dimensional flow patterns that appear after the transition. Three CCD cameras are used to observe the motions of the tracer particles from different view angles through the transparent heated disk made of sapphire. Particle images are recorded in the HDD recording system in ISS and they are downloaded to the ground for data analysis. A conventional 3-D PTV technique and a newly-developed multi-frame particle tracking method are combined to obtain the results that can help better understanding of oscillatory 3-D flow fields in the liquid bridges. It is shown that the flow pattern changes from a 2-D axisymmetric steady flow to an oscillatory 3-D non-axisymmetric flow under the supercritical conditions.

Other Link： http://www.jasma.info/wp-content/uploads/past/assets/images/jornal/28-2/2011_p126.pdf

Onset of Hydrothermal Instability in Liquid Bridge. Experimental Benchmark

V. Shevtsova, A. Mialdun, H. Kawamura, I. Ueno, K. Nishino, M. Lappa

FDMP: Fluid Dynamics & Materials Processing 7 ( 1 ) 1 - 27 2011 [Reviewed]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Tech Science Press Single Work

The experimental results from nine benchmark test cases conducted by five different groups are presented. The goal of this study is to build an experimental database for validation of numerical models in liquid bridge geometry. The need arises as comparison of numerical results with a single experiment can lead to a large discrepancy due to specific experimental conditions. Perfectly conducting rigid walls and, especially, idealized boundary conditions at the free surface employed in numerical studies are not always realized in experiments. The experimental benchmark has emphasized strong sensitivity of the threshold of instability to the liquid bridge shape. A clear distinction should be made between results belonging to the different disturbance patterns, i.e. different wave numbers. The results of benchmark contributors are in a satisfactory agreement when they are associated with the stability branch with an identical wave number. In this case the discrepancy of the results for determination of the critical parameters is about +-15%-18% and they can be used for the validation of numerical models.

Other Link： https://www.researchgate.net/profile/Marcello_Lappa/publication/235407848_Onset_of_Hydrothermal_Instability_in_Liquid_Bridge_Experimental_Benchmark/links/00463516c2518b69b0000000/Onset-of-Hydrothermal-Instability-in-Liquid-Bridge-Experimental-Benchmark.pdf

Numerical Study of Steady Thermocapillary Convection in a Cylindrical Half-Floating-Zone

Shaligram Tiwari, Koichi Nishino

International Journal of Fluid Mechanics Research 37 ( 6 ) 506 - 529 2010 [Reviewed] [Invited]

DOI

Language：English Publishing type：Research paper (scientific journal) Publisher：Begel House Joint Work

Numerical investigations are carried out to study the steady thermocapillary flow in a half-floating-zone, suspended vertically between two differentially heated disks of circular cross-section. The surface tension driven flow inside the floating zone gets strongly influenced by the flow conditions of the surrounding gas. Computations are carried out over a wide range of Marangoni numbers (Ma) to investigate the flow behavior in the floating zone and surrounding gas and heat transfer at the liquid-gas interface. A comparison of flow and temperature fields within the liquid bridge and the surrounding air under normal and microgravity conditions has been presented. Heating of the confined and unconfined ambient gas is observed to influence the radial and axial temperature gradients at the liquid-gas interface and within the liquid bridge which in turn affects the nature of thermocapillary flow.

Other Link： http://www.dl.begellhouse.com/journals/71cb29ca5b40f8f8,34053a9e69b46003,1759f48e00edb585.html

Numerical Investigation for Net Enhancement in Thermal-Hydraulic Performance of Compact Fin-Tube Heat Exchangers with Vortex Generators

Song Gil-Dal, Nishino Koichi

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY 3 ( 2 ) 368 - 380 2008 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Conjugate Heat Transfer Computation for Evaluation of Single-Blow Method for Compact Fin-Tube Heat Exchangers

Song Gil-Dal, Nishino Koichi

JOURNAL OF THERMAL SCIENCE AND TECHNOLOGY 3 ( 2 ) 219 - 233 2008 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Simultaneous Heat Transfer Enhancement and Pressure Loss Reduction for Finned-Tube Bundles with the First and Two Transverse Rows of Built-in Winglets

International Journal of Experimental Heat Transfer, Thermodynamics, and Fluid Mechanics 29 625 - 632 2005 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

3-D PTV Measurement of Oscillatory Thermocapillary Convection in Half-Zone Liquid Bridge

Experiments in Fluids 38 ( 3 ) 285 - 290 2004

Language：English Publishing type：Research paper (international conference proceedings) Joint Work

Measurement of Dynamic Surface Deformation of Liquid Bridge with Thermocapillary Convection by Using Temporal Speckle Pattern Interferometry

Journal of The Japan Society of Microgravity Application 21 ( 4 ) 267 - 275 2004 [Reviewed]

Language：English Publishing type：Research paper (scientific journal) Joint Work

PIV Measurement of Internal Flow Characteristics of Very Low Specific Speed Semi-open Impeller

Y.-D. Choi, J. Kurokawa, J. Matsui

Experiments in Fluids 37 617 - 630 2004 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

Temporal Speckle Pattern Interferometry for Measuring Micron-order Surface Motion of Liquid Bridge

Measurement Science and Technology 15 2284 - 2294 2004 [Reviewed]

DOI Web of Science

Language：English Publishing type：Research paper (scientific journal) Joint Work

混相流計測法

森北出版 130 - 133, 193-197, 257-262 2003

Language：Japanese Publishing type：Research paper (other science council materials etc.)

PIVハンドブック

森北出版 165 - 211, 212-220, 266-267, 282-283, 308-312 2002

Language：Japanese Publishing type：Research paper (other science council materials etc.)

Heat Transfer and Folw Characteristics of Fin-Tube Bundles with and without Vortex Generators

Experiments in Fluids 33 696 - 702 2002

Language：English Publishing type：Research paper (other science council materials etc.)

マイクロ流れの速度場計測

日本流体力学会会誌「ながれ」 20 ( 2 ) 83 - 91 2001

Language：Japanese Publishing type：Research paper (other science council materials etc.)

PIV Measurement of Internal Structure of Diesel Fuel Spray

Experiments in Fluids 29 ( 7 ) S211 - S219 2000

DOI Web of Science

Language：English Publishing type：Research paper (other science council materials etc.) Single Work

Stereo Imaging for Simultaneous Measurement of Size and Velocity of Particles in Dispersed Two-Phase Flow

Measurement Science and Technology 11 633 - 645 2000

DOI Web of Science

Language：English Publishing type：Research paper (other science council materials etc.) Single Work

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