In recent years, the development of functional materials and intelligent (smart) materials are active in solid area, in the fluid area as well Knowing beforehand its basic response to the impressed physical quantity from the outside is very important, when designing the application of such materials. We are focusing some Magnetic fluid (MF) and Magnetorheological fluid (MRF) and visualize the behavior under the external magnetic field by using the dark-field microscopy. This paper describes the results of the fundamental experiments to visualize the behavior of the magnetic particles in MF and MRF under the alternating magnetic field, and make clear the relation between its field intensity and frequency, and the particle's behaviors.

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Micro-bubbles cause various phenomena. Those can be used for sterilization and chemical reactions. It is for charge of micro-bubbles. It is necessary to observe micro-bubbles in magnetic field in order to use it efficiently.

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Micro-bubbles cause various phenomena. Those can be used for sterilization and chemical reactions. It is for charge of micro-bubbles. It is necessary to observe micro-bubbles in magnetic field in order to use it efficiently.

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This paper deals with the dissolution of microbubble in a turbulent round jet. We took detailed experimental data of velocity field and bubble radius by time-resolved optical measurements. Typical bubble radius is less than 80 um, which is equivalent to or smaller than the Kolmogorov's microscale of present turbulent flow. The velocity field of gas-liquid flow was measured by Particle Imaging Velocimetry-Laser Induced Fluorescence(PIV-LIF). The bubble radius was measured by Interferometric Laser Imaging(ILI). The experimental data indicates that the turbulent shear considerably enhance the gas dissolution. Experimental data of dissolution rate were compared with a correlation equation derived by Sugiyama et al. (2006), in which shearing motions of turbulent small eddies are taken into account. The dissolution process in the experiment shows good agreement with that predicted by the correlation equation.

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The present paper aims at establishing kinetic boundary conditions of methanol and water through the determination of condensation coefficients based on molecular gas dynamics analysis and shock tube experiment in weak vapor-liquid nonequilibrium states. The results show that, when the ratio of vapor pressure to saturated vapor pressure at the interface is close to unity, values of condensation coefficients of methanol and water equal to evaporation coefficient estimated by the resent molecular dynamics analysis. As the ratio becomes large, the condensation coefficients decrease. The pressure ratio dependency of a condensation coefficient is explained by the molecular gas dynamics analysis.

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Evaporation coefficients for interfaces between argon vapor and its droplets at 85 K are investigated by molecular dynamics simulations of liquid-vapor equilibrium state and evaporation into virtual vacuum for a droplet radii ranging from 10 Å to 40 Å. The result shows that evaporation coefficient becomes small as the droplet radius does small.

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Acoustic standing waves in a tube filled with a vapor is theoretically analyzed. The wave motion is excited by a sound source mounted on an end of the tube, the other end of which is closed by a solid wall and a condensed phase of the vapor is formed on it. The evaporation and condensation is therefore induced by the wave motion. The phenomenon concerned is studied on the basis of an asymptotic method for the Boltzmann equation. The asymptotic analysis shows that the wave motion is governed by the linear wave equation in the bulk vapor phase and the heat conduction equation in a thermal boundary layer appears near the boundary. The standing wave is determined by solving the two equations.

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Acoustic standing waves in a tube filled with a vapor is theoretically analyzed. The wave motion is excited by a sound source mounted on an end of the tube, the other end of which is closed by a solid wall and a condensed phase of the vapor is formed on it. The evaporation and condensation is therefore induced by the wave motion. The phenomenon concerned is studied on the basis of an asymptotic method for the Boltzmann equation. The asymptotic analysis shows that the wave motion is governed by the linear wave equation in the bulk vapor phase and the heat conduction equation in a thermal boundary layer appears near the boundary. The standing wave is determined by solving the two equations.

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Human blood flows are highly susceptible to physical and health conditions. Hence quantitative evaluation of blood flow helps the physical check up of individuals. However, the most convenient method is taking a blood sample, which can only examine ex vivo blood condition. We developed digital high speed video capillaroscopy to observe the capillary loops of blood vessels in the finger skin nail fold, of which blood flow can be easily visualized. We discuss the optimal selection of both light source and finger holder, in order to obtain images with both clearer contrast and less blur. We found that the combination of both the halogen light with focusing attachment and brush holder provides satisfactory results with qualitative evaluation by using image processing tools of MATLAB.

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This paper presents a new micro-flow diagnostic technique, "confocal micro- particle image velocimetry (PIV)", and its application to the internal flow measurement of a droplet passing through a square microchannel. The confocal micro-PIV system enables us to obtain a sequence of sharp and high-contrast cross-sectional particle images at 2,000 frames per second. Using the present confocal micro-PIV system, we can measure velocity distributions of micro-flows in a 240 × 180 gm region with a confocal depth of 1.88 gm. We also propose a three-dimensional velocity measurement method based on the confocal micro-PIV and the equation of continuity. This method enables us to measure three velocity components in a three-dimensional domain of micro flows. The confocal micro-PIV system is applied to the internal flow measurement of a droplet. We have measured cross-sectional velocity fields at different focal positions of a droplet traveling in a 100 gm (width) × 58 gm (depth) channel. A volumetric velocity distribution inside a droplet is obtained by the confocal micro-PIV and the three-dimensional flow structure inside the droplet is investigated. The measurement results suggest that a three-dimensional and complex circulating flow is formed inside the droplet.

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The authors propose a passive micro mixer with the Split-and-Recombine (SAR) structure. Two mixing fluids become the multilayer condition by the SAR Structure. Then, the contact area increases, the thicknesses of layer decreases, and the mixing can be accelerated. In this method, it is important to put the thickness of layers into the multilayer condition of even width to mix more efficiently. Result of the numerical simulation in a SAR structure shows that the position of the contact surfaces between two fluids can be controlled by changing the channel configuration of the split part. And also result of quantitatively evaluating mixing efficiency in the Cross SAR structure shows that an efficient mixing is possible, and a great mixing acceleration is obtained. It is conforms that the method of this mixing acceleration is very effective.

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The aim of this study is to develop a method to enhance mixing in a small-scale channel by an active control. In the one millimeter-scale study, it is shown that investigating the fractal dimension and the length of interface between the liquids in the upstream region can be a guideline for designing a better mixing channel. The comparison between the results of one millimeter and 500 micron scale experiments is also done.

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The authors have reported that minichannel flow system had high heat transfer coefficient. We investigated experimentally and numerically the heat transfer and flow structure of single and array minichannel combined with impingement flow system. The diameter D of the channel was 1.27 mm and length to diameter ratio L/D was 5. The minichannel array was so called shower head which was constructed by 19 minichannels located at the apex of equilateral triangle, the side length S of which was 4 mm. The mechanism of high heat transfer was studied numerically by the Reynolds averaged Navier-Stokes equation and k-co turbulence model. The limiting streamline pattern was correlated well to the surface heat flux distribution. The high heat transfer in the single minichannel was achieved by suppressing the development of boundary layer under strong pressure gradient near the channel inlet and by the formation of large recirculating flow system in the downstream plenum of the minichannel exit. These heat transfer mechanisms became dominant when the channel size fallen into the regime of minichannel. The heat transfer performance of minichannel array was equivalent to that of impingement jet.

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The effect of liquid viscosity on pump characteristics was tested for the diffuser-shaped valve-less micro-pump, which consisted of one diffuser/nozzle element and a variable volume chamber with diaphragm driven by a piezoelectric actuator. Experiment was done for the water and glycerin water solution (20 wt%, 40 wt%, 60 wt%). As the result of the present study, it was found that pump performance decreased with increase in the working fluid viscosity and that the decrease in the pump performance depends on Reynolds number of oscillating flow.

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The objective of this study was to measure unsteady fluid force acting on limbs when swimming. For this objective, we developed a robot arm, which has five degrees of freedom and can simulate swimming motion of both upper and lower limbs in water. The robot arm has tri-axial moment sensor at each joint and dynamometer which can measure the force and moment acting on the whole robot arm. In the exploratory experiment in a water tank, the four swimming strokes, that is, crawl, breast, back, and butterfly, were simulated. The resultant forces and moments suggested the usefulness of the robot arm in measurement of unsteady fluid force with swimming motion.

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There are a lot of people who are reluctant to do swimming because they cannot swim well. Therefore, in this study, we propose the bathing suit that assists the body to attach the buoyant material into swimsuit for those people. First, the experiment that takes a picture of the swimming movement is conducted. Next, swimming movement of this experiment is analyzed by the simulation theoretically and examined the effect of the swimming ability, buoyant material installation position and the amount. Then, we make a bathing suit which can change the installation position and the amount of the buoyant material, and detailed examination was done by the simulation and the senses evaluation. Finally, we calculated the calorie consumption of swimming and examined the influence that the buoyant material exerted on the calorie consumption.

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Water walking is a suitable exercise and effective for rehabilitation. However, body load of water walking has not been clarified. Therefore, in this study, walking simulation model, by which the fluid force acting on the lower extremity and the joint torque are able to be calculated, was developed based on SWUM (Swimming human simulation model). Then, joint torque and force of both land and water walking were calculated by this model, and merits of water walking in stance phase were clarified by comparing the joint torque and force of water walking with those of land walking. Finally, fluid and non-fluid components of joint torque and force were calculated, and from this, merits of water walking in both stance and swing phases were clarified.

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In this paper, the front crawl swimming is optimized for swimming speed and propulsive efficiency using Genetic Algorithm (GA). The GA is integrated into our swimming human simulation model SWUM, which was developed for analyzing swimming motion, and the fastest and most efficient strokes are numerically solved. Both the obtained strokes have their own features distinguished from the conventional strokes. From the analyses of the joint torque and fluid force, it is found that the fastest stroke is explained as 'full power during whole stroke', while the most efficient as 'full power in efficient moment'.

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A stoke of the back crawl stroke in the current competitive swimming is a style in which a hand palm moves on the character of S on the side of the body. In this study, the hand path of the back stroke was calculated with a physical model using experimental results of hand palm aerodynamic characteristics. The stroke path of the maximal efficiency and that of the maximal thrust force were obtained as drive angles, tilt angles and angles of attack. As a result, the stoke of the maximal efficiency is the conventional S-shaped stroke and that of the maximal thrust is the I-shaped stroke in which a hand palm moves parallel to the body axis towards legs with using only drag force.

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A stoke of the back crawl stroke in the current competitive swimming is a style in which a hand palm moves on the character of S on the side of the body. In this study, the hand path of the back stroke was calculated with a physical model using experimental results of hand palm aerodynamic characteristics. The stroke path of the maximal efficiency and that of the maximal thrust force were obtained as drive angles, tilt angles and angles of attack. As a result, the stoke of the maximal efficiency is the conventional S-shaped stroke and that of the maximal thrust is the I-shaped stroke in which a hand palm moves parallel to the body axis towards legs with using only drag force.

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Racing sailboats and in particular the America's Cup yacht are one of the most challenging subjects in the sports fluid dynamics. CFD plays an increasingly role in the design and analysis in the yacht racer, whereas the semi-empirical approach is also taken for the design of the yacht. In this study, the flow around a keel-bulb model of America's Cup yacht racer is simulated by 3-dimensional vortex method. The analysis is mainly focused on the flow structure behind the bulb at different leeway angle, which shows a complex flow pattern. Velocity profiles are compared with experimental data and time history of the side forces on the keel-bulb system are shown.

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The fundamental researches on movement analysis in batting of baseball were conducted by two high speed video cameras and two tn-axial acceleration sensors. The velocity analysis by using the advance setting and the signal processing were clearly shown. The velocities by both two-dimensional analysis and three-dimensional analysis were discussed. The images by DLT method using two high speed video cameras were linked with velocities of bat speed or left hand speed. The significance of three-dimensional analysis was shown by the statistical analysis.

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The optimization study on the fluctuating punted kick was carried out. It was found from the wind tunnel tests that the side force coefficient depended on the position of the lace of the ball. It has the positive and negative values. That becomes the key to fluctuate the ball during the flight. What are the features of the optimal punted kick in rugby? The objective of this paper is to provide the answers to these questions by optimizing the initial velocity and angular velocity vectors as well as the initial Euler angles for the punted kick. Three objective functions are considered, two of which are the number of extrema in the forward and the lateral directions. The third objective function is the hang time. For optimization all the objective functions must be maximized. The optimization was carried out by using an elitist non-dominated sorting genetic algorithm. The results are summarized as follows: in order to make the hang time longer, the initial pitch angle should be about 90° like a rocket. In the phase of rising, the smaller angle between the longitudinal axis of the ball and the direction of the flight path is preferable. In the phase of falling, the larger angle is preferable. In order to fluctuate the ball more frequently, the spin should be given to change the direction of the side force.

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Highly spinning golf ball aerodynamics is studied by wind tunnel experiments. To estimate a precise trajectory of golf ball 3-D flight, in this stage, more accurate and simultaneous measurement to confirm 4-components of aerodynamic forces on spinning golf ball is needed. We had challenged this problem with freely rotation and it's naturally decaying golf ball experiment system in wind tunnel flow.

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Highly spinning golf ball aerodynamics is studied by wind tunnel experiments. To estimate a precise trajectory of golf ball 3-D flight, in this stage, more accurate and simultaneous measurement to confirm 4-components of aerodynamic forces on spinning golf ball is needed. We had challenged this problem with freely rotation and it's naturally decaying golf ball experiment system in wind tunnel flow.

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This paper describes a pioneering work of practical application of an advanced vortex method in the field of fluid dynamics in sports science. The vortex method developed by the present authors is one of vortex element methods based on the Biot-Savart law, and it is known that the method provides a Lagrangian simulation of unsteady and vortical flows. In this study, in order to examine the applicability of the vortex method, three-dimensional, complex and unsteady flows around an isolated 100 m runner and a ski-jumper were calculated. Basic equations and mathematical treatment of the method are explained in this paper, and calculation conditions and panel data of deforming configuration of the athletes are described. As results of the present study, vortical and unsteady flow features around a runner and a ski-jumper are understood, and unsteady variation of aerodynamic forces corresponding to deformation of body configuration due to athletic motion are calculated. And, it is confirmed that the advanced vortex element method is a promising way to a grid-free Lagrangian large eddy simulation of unsteady and complex flows around dynamic bodies of athletes

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In this study, a new type of wind turbine utilizing magnus effect on rotating cylinders is introduced. For the wind turbine, spiral structures are equipped on cylinder surfaces to enhance magnus effect. At first, Lift and drag forces on a rotating cylinder are measured to evaluate aerodynamic characteristics of the cylinder. As the result, it was indicated that the lift force is enhanced for lower tip speed ratio of the cylinder by the spiral structures though the drag force is also gained. In the second stage, a test wind turbine with five rotating cylinders was constructed to estimate the basic characteristics of the magnus wind turbine with spiral structures. As the results, it was indicated that the effect of rotating speed of the cylinder is basically positive to power and torque coefficients for the test condition and the basic characteristic of the wind turbine is torque subjected.

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The authors have proposed an urban-type wind power generation system, in winch small wind turbines, accommodated within rooftops of urban buildings or houses, absorb wind powers enhanced by the roof configuration. For the purpose, the performance of a simple cross-flow type wind turbine was improved from a viewpoint of the casing flowpath. The efficiency was improved as much as 30% in a relative sense compared to the original simple casing. At the same time, however, the required pressure difference was also increased, which wifi be necessary to be improved hereafter.

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We developed a new wind turbine system that consists of a shrouded diffuser with a broad-ring brim at the exit periphery and a wind turbine inside it. We are now researching for larger scales of this wind turbine. In view of practical point, we must develop a more compact shrouded wind turbine. To investigate the optimal shape and length of this diffuser shroud with a brim, wind tunnel tests are employed. The shrouded wind turbine equipped with compact brimmed diffuser demonstrates a remarkable power augmentation compared with a bare wind turbine.

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