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A Micromixer Using the Chaos of Secondary Flow: Rotation Effect of Channel on the Chaos of Secondary Flow

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Open Journal of Fluid Dynamics 2012年第4期2卷 195-201页

作者： yasutaka hayamizu Shinichiro Yanase Shinichi Morita Shigeru Ohtsuka Takeshi Gonda Kazunori Nishida Kyoji Yamamoto Department of Mechanical Engineering Yonago National College of Technology Tottori Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan

The micromixer, which has a rotor with a curved channel, is studied experimentally. The secondary flow in a curved channel of rectangular cross-section is investigated using PIV (Particle Image Velocimetry) and LIF (Laser Induced Fluorescence) methods. Two walls of the channel (the inner and top walls) rotate around the center of curvature and a pressure gradient is imposed in the direction of the exit of the channel. The non-dimensional channel curvature δ=a/R is taken to be about 0.1, where 2a is the width of the channel, R the curvature radius of the channel. Other non-dimensional parameters concerned are the Dean number De=Reδ1/2, the Reynolds number Re=qdh/v, where q is the mean flow velocity in the channel axis direction, ν the kinematic viscosity, dh the hydraulic diameter of the channel, and the Taylor number Tr=2(2δ)1/2Ωa2/(δv), where Ω is the angular velocity of the rotor. Photographs of the flow in a cross-section at 180° downstream from the curved channel entrance are taken by changing the flux (De) at a constant rotational speed (Tr) of the channel walls. It is found that good mixing performance is obtained in the case of De≤0.1|Tr| and for that case secondary flows show chaotic behaviors. And then we have confirmed the occurrence of reversal of the mean axial flow.

关键词： Chaos Rotation Effect Secondary Flow PIV LIF

Heat Transfer Characteristics of Work Fluid Including Phase Change Material That Flow into Heating Surface from Narrow Path

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Open Journal of Fluid Dynamics 2014年第5期4卷 454-462页

作者： Shin-Ichi Morita yasutaka hayamizu Takanobu Yamada Akihiko Horibe Naoto Haruki Toshiaki Setoguchi Kazuma Adachi Department of Mechanical Engineering National Institute of Technology Yonago College Yonago Japan Department of Mechanical Engineering Kitami Institute of Technology Kitami Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan Department of Advanced Technology Fusion Saga University Saga Japan Graduate School of Machine Creative Engineering Nagaoka University of Technology Nagaoka Japan

Use of the low temperature (less than 100°C) energy contributes to effective use of heat resources. The cost recovery by power generation is difficult by using an existing system (the binary cycle or the thermoelectric conversion element), because the initial investment is large. The final purpose of this research is development of the low temperature difference drive engine supposing use in a hot-springs resort as a power source for electric power generation. In order that a traveler may look at and delight a motion of an engine, it is made to drive at low-speed number of rotations. An engine cycle of this study is aimed at the development of Stirling cycle engine which can maintain high efficiency in small size. This kind of engine has simple structure;it brings low cost, and it is easy to perform maintenance. However, it is difficult to obtain enough output by this type of engine, because of its low temperature difference. This paper deals with the heat transfer characteristic that the working fluid including a phase change material flows into the heating surface from the narrow path. In order to increase the amount of the heat transmission, Diethylether is added to the working fluid. Diethylether is selected as a phase change material (PCM) that has the boiling point which exists between the heat source of high temperature and low temperature. The parameters of the experiment are additive amount of PCM, rotational speed of the displacer piston and temperature of heat transfer surface. It is shown that it is possible to make exchange of heat amount increase by adding phase change material. The result of this research shows the optimal condition of the difference in temperature in heat processing, number of revolutions, and addition concentration of PCM.

关键词： Phase Change Material Heat Transfer Low Temperature Difference Working Fluid

Micro T-Mixer with Baffles: Effect of Baffle Height and Setting Angle on Mixing

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Open Journal of Fluid Dynamics 2023年第4期13卷 206-215页

作者： Miah Md Ashraful Alam Taichi Hirano yasutaka hayamizu Takuya Masuda Tatsuki Hamada Shinichi Morita Manabu Takao Department of Mechanical Engineering for Transportation Faculty of Engineering Osaka Sangyo University Osaka Japan Advanced Engineering Faculty National Institute of Technology Yonago College Tottori Japan Department of Mechanical Engineering National Institute of Technology Yonago College Tottori Japan Department of Mechanical Engineering Kitami Institute of Technology Hokkaido Japan Department of Mechanical Engineering National Institute of Technology Matsue College Shimane Japan

Chaotic mixing in eight different types of micro T-mixer flow has been studied experimentally and numerically. The present experimental study was performed to visualize two-liquid flows in a micro T-mixer with baffles. The Reynolds number, baffle height and setting angle were varied to investigate their effect on the mixing performance. Three micro T-mixer models were produced, which are several centimeters long and have a rectangular cross-section of few millimeters a side. The mixing of two-liquid was measured using the laser induced fluorescence (LIF) technique. Moreover, three-dimensional numerical simulations were conducted with the open-source CFD solver, OpenFOAM, for the same configuration as used in the experiments to investigate the detailed mechanism of the chaotic mixing. As a result, it was found that the mixing of two-liquid is greatly improved in the micro T-mixer with baffle. The baffle height and setting angle show a significant influence on the mixing performance.

关键词： Micromixer Baffles Liquid-Liquid Mixing LIF CFD

Behavior of Motile Sperm in Taylor-Couette Flow: Effect of Shear Stress on the Behavior of Motile Sperm

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Open Journal of Fluid Dynamics 2013年第2期3卷 9-13页

作者： yasutaka hayamizu Toru Hyakutake Koji Matsuura Shinichiro Yanase Shinichi Morita Shigeru Ohtsuka Takeshi Gonda Department of Mechanical Engineering Yonago National College of Technology Tottori Japan Graduate School of Engineering Yokohama National University Yokohama Japan Graduate School of Natural Science and Technology Okayama University Okayama Japan Research Core for Interdisciplinary Sciences Okayama University Okayama Japan

Infertility is often cited as one of the causes of a declining birthrate, which has become a serious social problem in recent years. Processes by which motile sperm can be safely and easily sorted are therefore important for infertility treatment. Therefore, as a new sorting method, microfluidic sperm sorter using the microfluidic system has been developed. To improve more separation efficiency of this device, it is necessary to know the behaviors of motile sperm in the microchannel where the sperm undergo shear flow. The previous study implied the necessity of the modeling of motile sperm in the shear flow. In the present study, therefore, we experimentally investigated the behavior of the motile sperm in the Taylor-Couette flow using PTV (Particle Tracking Velocimetry) method. The experimental results showed that the ascent of the shear stress led to the increase in the sperm velocity, and the direction of the sperm velocity was opposite to that of the flow.

关键词： Motile Sperm Taylor-Couette Flow Shear Stress PTV

Structure of Periodic Flows through a Channel with a Suddenly Expanded and Contracted Part

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Micro T-Mixer with Baffles: Effect of Baffle Height and Setting Angle on Mixing

Open Journal of Fluid Dynamics（流体动力学） 2023年第5期

作者： Takuya Masuda Toshio Tagawa Miah Md. Ashraful Alam yasutaka hayamizu

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