We have developed the basic equation of the orientational distribution function of oblate spheroidal hematite particles that conduct the rotational Brownian motion in a simple shear flow under an applied magnetic field. An oblate spheroidal hematite particle has an important characteristic that it is magnetized in a direction normal to the particle axis. Since a dilute dispersion is addressed in the present study, we have taken into account only the friction force (torque) with neglecting the hydrodynamic interactions among particles. This basic equation has been numerically solved in order to investigate the dependence of the orientational distribution on the magnetic field strength, shear rate and rotational Brownian motion, and also the relationship between the orientational distribution and the transport coefficients such as viscosity and diffusion coefficient.

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Relationship between flow resistance and rough wall surface having semicircular ribs was investigated experimentally. Concentric cylinder device was employed to carry out the experiments. We measured flow resistance directly by the torque meter of the inner cylinder and velocity distribution by the LDV. In order to estimate the flow resistance over the wall surface having semicircular ribs, we focus on the interval of ribs. The approaching velocity to the next rib can be approximated by the measured velocity distribution and interval of ribs. Based on this approximation, we can estimate the approaching velocity without measurement of velocity distribution. Finally, we constructed the model for the prediction of flow resistance, and we estimated the pressure drag and frictional drag by this model. As a result, the estimated flow resistance has good agreement with the measured flow resistance.

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We experimentally studied point sink flows in a linearly stratified fluid under the rotating system. When the system is not rotating, only a layer of fluid adjacent to the sink level is withdrawn. It is called selective withdrawal, and" we carry out experiments to examine how it behaves in a rotating system. A linearly .stratified fluid is filled in a water tank and a point sink is located either in the middle of the tank or near the wall. The flow is visualized by PIV. When the sink is located in the middle of the tank, the withdrawal-layer thickness becomes wider as time elapses, whereas if the sink is located near the wall, the withdrawal-layer thick ness is almost unchanged in time.

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We have investigated the negative magneto-rheological effect of a dispersion composed of spindle-like hematite (α-Fe_2O_3) particles by means of the experimental method. The spindle-like hematite particles were synthesized by aging a solution of FeCl_3 and KH_2PO_4 for 72 hours at 373K. In the present study we have considered a glycerol-water-based dispersion in order to clarify the influences of the shear rate and the magnetic field strength on the negative magneto-rheological effect. The measurement of the viscosity was carried out using the rotational-type rheometer in an external magnetic field generated by the Helmholtz coils.

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We have shown the basic equation of the orientational distribution function of prolate spheroidal hematite particles that conduct the rotational Brownian motion in a simple shear flow under an applied magnetic field. The equation has been solved numerically in order to investigate mainly the influence of the spin rotational Brownian motion on the orientational distribution, the negative magneto-rheological effect and the characteristics of magnetization.

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The bifurcation time scale for the onset and the decay between Couette flow and the Taylor-vortex flow is investigated by the numerical approach. The lengths of the coaxial two cylinders are finite and the flow develops between the outer and inner cylinders. The development of the flow amplitude is assumed to obey the Landau equation, and the time constants in entire azimuthal sections are evaluated by fitting the time series of the velocity components to the solution of the equation. The time constant of the decay flow is more than three times larger when it is compared with the time constant of the onset flow. It also shows larger value at the inner region, and the value is small near the end wall of the cylinder where Ekman Layer appears.

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Behavior of wall wake behind a two-dimensional flat plate placed perpendicularly on a ground plane was experimentally investigated with the aid of a laser Doppler velocimetry. The experiment was performed for three types of flat plates with the height of H = 15 mm, 20mm and 40mm. From distribution of iso-velocity lines in a cross-stream plane, we found that two-dimensionality of the velocity field in wall wake region was not achieved for low height flat plate. This trend was observed at the streamwise location X ≦ 20H. Velocity vectors in the horizontal plane indicated that a flow over the flat plate generated two vortices near both side walls and the recirculation region was reduced with increasing in the ratio of the plate height H to the tunnel height h (H/h). These phenomena caused difficulty of realizing the two-dimensionality of the velocity field in the wall wake region.

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We have investigated various problems that arise in applying the Brownian dynamics method to a suspension composed of rod-like hematite particles, which have a magnetic moment normal to the particle axis direction. The accuracy and the deviation of simulation results from theoretical solutions have been discussed by comparing with the theoretical results that were obtained by solving the basic equations of the orientational distribution function. The present simulation results can well qualitatively reproduce the characteristics of the negative magneto-rheological effect that was predicted by the previous theoretical investigation.

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A laser 2-focus velocimeter (L2F) was used for the measurements of the velocity and size of droplets in the dense region of diesel spray which was intermittently injected into the atmosphere. The diameter of the nozzle orifice was 0.113 mm. The injection pressure was set at 40 MPa by using a common rail system. The L2F had a micro-scale measuring volume which consisted of two foci. The distance between two foci was 17 p.m, and the focal diameter was about 3|am. The maximum data sampling rate of the L2F system wajs markedly high as 15 MHz. Measurements were conducted at 15mm and 20mm downstream from the nozzle. The number density was calculated at several specified times from the measured velocity, size and arrival time of droplets. The sizes of droplets were larger at the spray center and the spray periphery than at the spray off-center. The result shows a strong inverse correlation between the droplet size and droplet number density.

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Heat transfer and pressure characteristics of two-dimensional offset jet of fully developed flow were investigated experimentally. The local Nusselt number and the wall static pressure coefficient were measured for the jet Reynolds number Re from 1.5x10^3 to 7.0x10^3, and the offset ratio Hlh from 0.5 to 1.5. The result shows that the two peaks appear at the Nusselt number distributions for the laminar and the transitional flows with Hlh =0.5 and 1.0. It is found that the maximum pressure point coincides with the maximum Nusselt number location for the laminar and turbulent flows.

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Development of the optimization system for aerodynamics control using plasma actuator has been conducted. The system which uses the Efficient Global Optimization method was designed to explore the optimum value with a small number of sampling. By using the current optimization system, the drag minimization for bluff body using plasma actuator, with multiple design variables, was successfully carried out. This indicates the optimization method developed in this study is evaluated as effective and can reduce a numerous number of sampling during wind-tunnel experiment.

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In this study, the flow characteristics by surface wave plasma (SWP) are investigated using argon and oxygen as working gases. The relationship between wetting characteristics and electron excitation temperature is examined. With increasing argon ratio, the variation of contact angles each position becomes large. This is because the sputtering effect of argon atoms is more influenced by flow than the oxidation reaction of oxygen atom

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This paper proposes a basis of a method for ultrasound treatment and diagnosis integration to develop breast cancer therapy. By utilizing the scattering theory based on the linear wave equation in an inhomogeneous media (such as biological soft tissue composed of fat, skin, and lesion), an image reconstruction of sound speed and attenuation coefficient may be performed. We describe in detail a basis of formulation of ultrasound propagation in the inhomogeneous media. Furthermore, we have performed a computation on the sound field of a simplified model of breast during ultrasound exposure toward design of a ring array transducer.

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Wave slope was evaluated by measuring both significant wave height and length in a broad wind speed range. Experiments were conducted in a high-speed wind wave tank. The results show that the significant wave length increases steeply with free-stream wind-speed at low wind speeds ( U_∞ <15 m/s), increases gradually at middle wind speeds (15 ≦ U_∞ < 27 m/s), and increases steeply again at extremely high wind speeds (U_∞>= 27 m/s). The wave slope increases with the free-stream wind-speed in the low wind speed region ( U_∞ <15 m/s), but it reaches a constant value in the high wind speed region (U_∞ ≧ 15 m/s). These results suggest that the trend of wave development in the high wind speed region is different from that in the low wind speed region owing to wave breaking.

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The objective of this study is to understand the aerodynamic characteristics of three-dimensional flow around square cylinder with grooves. This study clarifies the effects of the drag reduction using the grooves of square cylinders. Experimental investigations on the flow around square cylinders were implemented in the range of 5.0x10^4=<R=<1.0x10^5. Flow visualizations with the suspension method of the flow were also implemented. The results demonstrate that a drag coefficient also decreases, As the groove width become smaller. Furthermore, a drag coefficient increases by enlarging a groove interval. It is found that the drag coefficient with groove decreased by about 8% in compared without groove.

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The aim of this study is to control the diffusion and the direction of the jet flow issuing from the pentagonal duct. In order to grasp the flow feature the flow structure of the jet was visualized by a LIF method. The velocity measurements of the jet flow issuing from the pentagonal duct with and without the synthetic jet were carried out using hot-wire sensors and the constant temperature anemometer. And decays of the maximum velocity and the jet half value widths were investigated by analyzing the velocity distributions. As a result, it has been found that the jet width with synthetic jet becomes large, comparing with that of the jet without one. Moreover it has been also clarified that the jet is induced by the synthetic jet.

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The insect obtains driving force and lift force by flapping. The dragonfly changes its flapping state of four pieces of wings according to flight conditions. The wing performance of the robot dragonfly which was able to fly was measured in order to grasp its flight states. The wing performances with the three configurations of the fore and the hind wings were compared in two conditions, steady and unsteady. One of the configurations was the state when the fore and the hind wings flapped synchronously seen in a taking off and landing and turning state phase. The others were the states when the fore and the hind wings alternatively flapped seen in a cruise state. The phase difference in the flapping of the hind wing advancing to that of the fore wing is 90° and 180°. The followings were obtained by these experiments: Free flight conditions of the mechanical dragonfly were realized by wind tunnel measurements. Higher lift force by flapping compared with steady state was confirmed as unsteady lift. Lift force exceeding the body weight was obtained in flapping phase angles of the hind wing advancing for the forewing at the time of 0° and 90 °.

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In a long-distance bicycle road game, in order to make the main rider win, an entire team makes a formation and assigns the main rider in an advantageous position for less drag. This study verified the effects from the formation consisted of multiple riders, usually called "train," with replicas aerodynamically. Four replicas were used as a train in drag force measurement and flow visualization. Bicycle replicas were fixed onto a ground plate, and the spacing of each replica was kept constant. Drag force of each replica was measured with three component load cell. Flow visualization in a smoke wind tunnel was also carried out in a horizontal plane at the riders' height. Several train formations expected to reduce drag including cross winds were attempted. As a result, the least drag on the replica of the main rider was obtained when it was placed at the end of the train in a linear arrangement. The results of the flow visualization also explain these phenomena well.

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This paper describes the optimization of the design of a discus and the skill with which it is thrown. The objective function for optimization is the flight distance, where longer is better. Thirteen control variables are considered, eleven of which are concerned with the skill of the thrower. These determine the launch conditions, which are controlled by the thrower when he or she throws the discus. The other two variables are concerned with the discus itself. These are the moment of inertia on its transverse axis and the mass of the discus. It was found that the optimized flight distance was 77 m. The optimal initial spin rate on its axis of symmetry prevents the falling of the discus during the flight.

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Spatial filter velocimetry (SFV) based on spatial filtering of time-series particle images proposed by Hosokawa and Tomiyama is applied to a planar bubble plume to examine its applicability to simultaneous measurement of bubble and liquid velocities. The edge detection process is added in the SFV processing to reduce the size of image pattern and to obtain accurate bubble velocity. Bubble regions in the recorded images of the planer bubble plume are detected by using a labeling process, and the particle and bubble images are generated by masking the bubble region and by inversing the bubble region, respectively. Then, SFV processing is applied to particle and bubble images to obtain liquid and bubble velocities, respectively. The measured results clearly demonstrate the potential of SFV for simultaneous measurements of liquid and gas velocities in two-phase flows.

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In order to predict aerodynamic sound, it is necessary to measure surface pressure fluctuations or distribution of a vorticity fields. The space measurements of these values are quite difficult. Then the predictions of aerodynamic sound are hard by using the conventional fluid dynamics measurement tools. Recently, PIV and PSP are candidates of breakthrough technique for aeroacoustics measurements. In this paper, I introduce some examples applied to aeroacoustics investigation to PIV and PSP.

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Simultaneous multi-plane measurement of planar laser induced fluorescence (PLIF) and stereoscopic particle image velocimetry (PIV) to investigate three-dimensional structures of turbulent premixed flames is introduced in this manuscript. Wavelength-based dualplane stereoscopic PIV, which can provide nine components of velocity gradients, was developed and combined with dual-plane CH PLIF and single-plane OH PLIF. The simultaneous measurement was applied to methane-air turbulent premixed flames in the swirl-stabilized combustor. three-dimensional flame structures including the spire structure which has been shown by the previous direct numerical simulation (DNS) of turbulent premixed flame was clarified. Magnitude of strain rate, which is evaluated from nine velocity gradients, shows high value in unburnt region except for the region engulfed by burnt gas. Moreover, quad-plane PLIF which has been developed to investigate threedimensional flame structure in more detail is introduced in this manuscript.

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Multipoint simultaneous measurement of velocity and thermal fields using an array of five three-wire probes, each composed of an X-type hot-wire and a fine cold-wire, is introduced to investigate spatiotemporal structures in an adverse-pressure-gradient turbulent boundary layer. If we notice the frequency response of the fine wires, this technique is promising to capture near-wall turbulent structures with high temporal resolutions.

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