In this study, the influence of the flow around the impeller on the broadband noise in the high frequency domain generated by a propeller type wind turbine is discussed. The actual wind turbine is measured by the wind tunnel test; the flow around the impeller immersed in the uniform flow is solved by the numerical simulation. In comparison on the free torque condition, the noise of the tip speed ratio 12 becomes 7.6 dB larger than the noise on the tip speed ratio 8.2 due to the broadband noise in the high frequency domain. Because the flow is separated at the vicinity of the leading edge from the hub side to mid-span, the aerodynamic noise is concentrated at the leading edge side, whereas the noise source of the blade tip side concentrated to the trailing edge side because the flow is attached to the blade.

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In Shinkansen lines in areas of heavy snowfall, snow-shelters linking neighboring tunnels are frequently built for snow disaster prevention. These shelters can also become a countermeasure against a micro-pressure wave by installing horizontal slits on their side walls. In this study, a field measurement in an actual snow-shelter section in Shinkansen line is conducted for investigating the micro-pressure wave emitted from the slits of the shelter. Furthermore, a numerical analysis is also conducted under the conditions corresponding to the field measurement. The results of the numerical analysis indicate that the directivity of the micro-pressure wave emitted from the horizontal slits on the shelter is considerably different from that of the micro-pressure wave emitted from the ordinary exit portal of the tunnel.

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When a train travels through a tunnel at high speed, large pressure variations are generated in the tunnel. It is essential to accurately predict these pressure variations when planning to increase the speed of Shinkansen. To estimate the pressure variations by train passage through a tunnel, scale model launching experiments using an axisymmetric model and an actual shape model have been conducted. Moreover, numerical simulation has been developed to predict the pressure variations. As a result, it is shown that the pressure variations are approximately inversely proportional to the square of the distance from the train center. The numerical simulation results agree well with the results of model experiments.

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An impulsive pressure wave emitted from a tunnel portal, called a micro-pressure wave, is one of the important wayside environmental problems in high-speed railways. A tunnel hood with openings on its side wall installed at the portal of the train entrance side is the principal countermeasure for reducing the micro-pressure wave. However, the micro-pressure wave tends to have large peak value around openings of the hood when the micro-pressure wave is emitted from the tunnel exit portal with the hood. In this study, we carried out the model experiment focused on the effects of the tunnel hood with openings installed at the portal of the train exit side. In addition, we developed a simple theoretical model simulated the micro-pressure wave around openings of the hood.

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The flapping robot is already made by many researcher in the world, but cannot fly as same as real insect and bird. Among them, dragonfly has been especially paying attention. Dragonfly perform very advanced flight. It is caused by the difference in partial stiffness of the wing. The purpose of this study is investigation of the effects by the difference of partial stiffness. Especially, dradonfly may be changed stiffness of the wings between the up stroke and down stroke. Therefore,it is necessary to compute changing the Young's modulus between the upper and lower surface.

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The purpose of this study is elucidating the mechanism of mosquito's flight. The motion of mosquito's wings consists of three representative motion; flapping, lead-lug and feathering motion. The feathering motion is a rotational movement which is centering on a wing leading edge. The mosquitoes are performing this motion passively produced by fluid forces and so on. In order to build the enlarged model which simulates this motion, we need to measure the stiffness of the mosquito's wings. The bending stiffness of the mosquito's wings were measured by the experiment using a cantilever. The enlarged wing model was designed based on its results. We observed the flapping motion of the enlarged wing model in the very low velocity wind tunnel and verified whether the feathering motion can be simulated.

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A sperm sorter using microfluidic system (MFSS) has been developed to solve sterility caused by abnormality in male sperm. To improve more separation efficiency of this device, it is necessary to know the behavior of motile sperm in detail. Under these backgrounds, the movement of the sperm in the microchannel was investigated in the present study. The previous study clarified that the modeling of the behaviors of motile sperm in the shear flow was necessary. Therefore, in the present study, 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 sperm velocity increased with the ascent of the shear stress and its direction is opposite to that of the flow.

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In order to steepen the output wave shape while increase frequency of present HFOV (high-frequency oscillatory ventilation), an acoustic compressor consists of piston driver and tube with varying cross-section area has been adopted to generate the desired shocklets. Also, the results of experiment and numerical simulation have been compared with each other for verification. Due to the acceleration limit of the piston in this experiment, apparent steepening of output wave has not been achieved, whereas in numerical simulation, the distinct steepening of output wave has been observed with larger acceleration. In the meantime, the fabrication of lung model is in progress aims at observing the flow phenomena induced by shocklets with assistance of PIV and facilitating the analysis of ventilation efficiency.

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Recently, deoxyribonucleic acid (DNA) has attracted much attention to be utilized for technological applications of its various functions. In our studies, self-assembled network patterns of poly(dA)-poly(dT) DNA on mica and highly oriented pyrolytic graphite (HOPG) surface were successfully observed by atomic force microscopy (AFM), which is preprocessed by a specific solution concentration of MgCl2. Focusing on the associated self-assembly mechanism, we develop and perform coarse-grained molecular dynamics simulations, in which 50 base-pairs (bp) long DNA fragments are modeled considering both intra- and inter-molecular interactions between the DNA and HOPG surface in aqueous solution. As a result, the network pattern formation, in which DNA fragments make bonds and bundle structures, are replicated. It is indicated that thermal fluctuations in solution work effectively to enhance the assembly process. Furthermore, characteristics of self-assembly of DNA can be classified by the fractal dimension.

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The objective of this study is to understand the process of splash erosion due to impacting of raindrop onto soil. This is investigated experimentally using a high speed CMOS camera. To understand the phenomena qualitatively, the soil model was developed. The model simulates the fine sand where the diameter of soil particle is 0.1mm. A dent was formed by the impact of droplet on the soil. The droplet deformed with the impacting, and formed the film-flow. The suspension of soil particle was caused with the shear force due to the film-flow. The suspended particle was not entrained into film-flow. The suspended particle was initially settled beside the film-flow. Thus, the suspended particle was not wet.

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By means of an inkjet printing device, a pressure-sensitive dot array sensor has been developed for unsteady pressure measurements. A conventional bi-luminophore anodized aluminum Pressure-Sensitive Paint (AA-PSP) prepared by a dipping method does not work well due to the interference between the two luminophores. To avoid this problem, we developed a pressure-sensitive dot array sensor on an anodized aluminum substrate using Ru(dpp)3 as a pressure-sensitive luminophore dissolved in four solvents: methanol, dichloromethane, chloroform, and the mixed solvent of dichloromethane and chloroform. Formed PSP dots exhibited significantly different properties including the luminescence intensity distribution inside the dot and pressure sensitivity by the solvents. As a result, the PSP solutions with dichloromethane or the mixed solution of dichloromethane and chloroform, which evaporated quicker than other solvents, formed dots with the uniform distribution of luminescence and showed that comparable pressure sensitivity with conventional AA-PSP prepared by a dipping method.

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A fast response pressure-sensitive dot array sensor has been developed by means of an inkjet printing technique on an anodized aluminum substrate, which has been used for unsteady flow measurements. However, PtTFPP based dot array sensor has several problems: non-uniform distribution of luminescent intensity due to "coffee ring effect" and low luminescent intensity. To solve these problems, we fabricated the PtTFPP-based dot array sensor on an anodized aluminum substrate with hydrophobic treatment. The hydrophobic treatment was applied to an anodized aluminum in three ways: dipping in the solution of dodecanoic acid in hexadecane, dipping in the solution of dodecanoic acid in water, and spraying the fluorine hydrophobic coat. The effect of the three hydrophobic treatments on the characteristics of PSP dots was investigated.

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The effect of ambient pressure on droplets' evaporation is investigated by means of threedimensional Direct Numerical Simulation (DNS). The results show that as the ambient pressure increases, the droplet lifetime increases at low initial gas temperature of 1000 K, and decreases at high initial gas temperature of 1500 K, respectively, for both cases with and without combustion. In addition, the decrease of droplet lifetime at high initial gas temperature of 1500 K becomes more remarkable for the cases with combustion.

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Recently, terrorism is one of most daunted dangers in the world. Chemical terrors have high mortality rate, and tend to wreak the secondary disaster. For these reasons, research and development of measures for decontaminations are emergent. Chemical agents emission and infiltration are usually investigated with experiments, but the experiment is so dangerous because of the toxicity. Therefore, in this study, computational fluid dynamics is used to reproduce evaporation and infiltration of chemical agents. Comparing the numerical results with the experimental data, it is confirmed that the numerical data are in good agreement with the experimental data. In addition, volatilization volume and infiltration volume are coupled with droplet geometry to simulate the temporal change of droplet shape and residual mass.

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Sanriku coastal regions were severely damaged by the earthquake on March 11, 2011. Iwate university efforts to promote reconstruction of marine products industry in this region by supports of the Japanese government. In this study, the aim is improvement of the efficiency on kelp drying process which is one of fabrication process of kelp which is one of the main products of the Sanriku coast, and it was investigated by computing thermo-fluid dynamics in the drying facility. It was clarified that most of the heat is discharged from exhaust fan which is necessary to discharge steam from kelp among drying and the heat distribution is non-uniform.

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A tilt-rotor plane represented by V-22 Osprey has an accurate aviation control capability and a high flight capability, because it has advantages of both of a helicopter and an airplane. However, rotation of twin-engine prop-rotors or changing of the modes of the plane will create very complicated flows. To simulate these complicated moving boundary problems, computational method for complicated shapes, movements and deformations is required. Therefore, in this paper, moving computational domain (MCD) method using unstructured grid is constructed. Furthermore, moving grid method for large deformation is applied to the method. And last, as application of present methods, the flight of tilt-rotor plane is simulated.

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Recently, development of a micro-UAV(Unmanned Aerial Vehicle), which moves in small and complicated 3D spaces freely and is equipped with multitasking sensors, is required for gathering information and resource work in disasters, and monitoring for security purpose. In this study, a quad-rotor is focused as a micro-UAV. The purpose of study is to investigate effects of the rotor interval on the characteristics of flow field around a quad-rotor in hovering. The velocity fields are measured by PIV. The 4-wakes past each rotor are induced toward each other and they are gathered together. It is found that the wakes are gathered to the center of all wakes with decreasing rotor interval.

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We devised newly the manufacturing process of a semiconductor-type sensor for the pressure measurement within the range of several Pa and with the frequency response of the order of 100Hz using MEMS (Micro Electro Mechanical Systems) technology and examined the static and the dynamic characteristics of the sensor. The results obtained were good linearity and high response of the sensor. Moreover, measurement was made of a pressure on the flat-plate wing at the order of 104 of chord Reynolds numbers. As a result, it was found that the sensor respond to the separation phenomena of wing well.

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Ice accretion in the form of glaze on rotor blades was investigated experimentally with a commercially available axial fan. In the experiments, fine water droplets generated by a spray nozzle were drawn into the axial fan in a low temperature room. Observations of ice shape and mass measurements of the ice were carried out to understand fundamental features of the glaze on the rotor blades. From the observations, we found characteristic shapes of the glaze near the leading edge of the fan blades which was caused by runback ice accretion influenced by the centrifugal force.

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Measurements were made of U and V components of instantaneous velocity in the wake of vertical axis wind turbine model using X type hot-wire, focusing on the issue of change of wind environment around the model. We measured the distribution of the phase-averaged velocity in the wake flow in this experiment, moreover, examined some influences that the interference between the blades exerted on the flow field around the wind turbine. From these experimental data, the integral quantities of mean velocity in the wake flow, turbulent energy; momentum loss; were compared with three, four and five pieces of model- turbine blades. Results obtained, it is to show similar properties regardless of the number of blades.

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Microbubble(MB) can be applied for cleaning of hydrophobic compounds on substrates. To characterize interaction between MB and the comounds, we observed surface of casted hydrophobic ink on glass, and surveyed loss of weight after cleaning using MB generating device by hydrogen bubble method and a microscope. The observed images on the ink after cleaning show the decrease in number of the holes generated by adsorption of MBs on the substrate decreased and the increase in diameter of the holes becaseue of increasing diameter of MB as the surface of the ink was distant from the electrode. We found a significant difference between the removals of the ink weights at the distance of 10 mm and 40 mm. These results suggested that the efficiency of cleaning of the hydropobic ink increased by generating MBs with diameter of 10 μm.

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To make effective use of cavitation, the larger impact force is desirable. In cloud cavitaion, the shock pressure is several times than that of single bubble burst. The intensity of jet catitation by using the multi-hole orifice is enhanced as the result of interaction and coalescence of vortex cavitation. When the distance between the holes is the smaller than the diameter of the holes, vortex cavitation approaches each other and grow up the massive bubbles. The acceleration of the cavitation vibration increases in intensity. In the case of the large distance between the holes, it does not coalesce and the acceleration value stays low values.

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Currently, needle-free injection system has been developed all over the world instead of typical injection system with a needle. Generally, the free injection system can be divided into a powder injection, a depot type injection and a liquid injection. In particular, the powder injection is mainly investigated recently, but it is said that the liquid injection is more effective than the powder injection in the case that the drug is transported at the deep position of subcutaneous tissue. However, the study of liquid injection is not conducted as much as that of powder injection. The goal of this study is to deliver the drug to arbitrary area of the human tissue without pain. Therefore, the objectives in the present study is to investigate the way to generate high speed micro water jet and to clarify the behavior of the water jet inside the body with viscoelasticity.

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Numerical analysis has been carried out for a single bubble flow in an electric conducting fluid under the influence of a vertical uniform magnetic field. It is assumed that the both two phases are the incompressible Newtonian fluid and viscous dissipation and Joule heat are neglected. The dimensionless governing equations for an axisymmetric cylindrical coordinate system have been numerically solved using the HSMAC algorithm combining with the level set method. The numerical results reveal that the electromagnetic force acts to suppress the separation vortices behind the bubble and to elongate the bubble shape along the vertical direction.

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In a semiconductor devise fabrication process, cleaning process has shifted to single-wafer spin cleaning from bath method. For the single-wafer cleaning, effective liquid infiltration into micro scale pores is important. In this study, we theoretically and experimentally investigate the liquid infiltration process into closed end tubes. From the estimation of force balance, we found that the surface tension force is not enough for the infiltration of order of 100 ?m tubes and it is necessary external pressure to fill the tube. In addition we experimentally observed the relationship between external applied pressure and air volume in the tubes. As a result, it is found that the air compressibility is the dominant factor for the liquid infiltration and dissolution has a low impact.

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The deformation of a water droplet on a solid wall is simulated by incompressible SPH method. The wettability of surface and the surface tension are modeled by giving attractive force between the particles. It is shown that the model can represent the difference of the wettability. The phenomenon where a droplet that touches the boundary between hydrophilic and hydrophobic surfaces is moved because of difference in the wettability is successfully simulated.

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The most difficult way to prevent infection among some infection routes is viral droplet nuclei transmission. Droplet nuclei are generated during coughing and sneezing, and suspend for a long time. Hence, specifying its infection route is important issue. The behavior of the droplets is governed by the physical principles. In addition, environmental factors, such as temperature, relative humidity and droplet size, also affect their dispersion and determining the survival. Thus, in this paper, first airflow in the crowded train was analyzed by using CFD.

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A method for prediction of particle behavior in semiconductor device manufacturing equipment, in case of wafer inspection equipment operating in atmospheric pressure, was developed. Allowance of particle size has recently been 30 - 50 nm. In this case, the force which is worked on the particle by air flow is mainly drag force. Therefore the trajectory of particle is thought to correspond with the stream line of air flow. The first step, we assigned particle sources on the edge of wafer, where the wafer was sliding with resin chucks. The second step, we simulated air flow and seeked the stream lines through the particle source. The last step, we estimated the approach of the stream lines to the wafer. By considering the estimation, we can control the air flow in the equipment to reduce particles adhering on the wafer.

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Recently, in various areas, equipments to separate and classify nano-size particles are required. We have investigating a new solid-liquid separator in order to efficiently separate nano-particles from liquid. This separator enables us to separate and classify nano-size particles by using centrifugal force and differences in specific gravity. A rotating screw in the separator is deformed by centrifugal force and flow drag, and thus the screw deformation may change the separation performance. Therefore, it is required to consider the screw deformation for the optimum design. In the present study, we computed the fluid-structure interaction between the screw and liquid with MPS method. It is confirmed that the flow field in the separator is changed by the screw deformation.

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In order to investigate the characteristics of radiation around Si-based heat-resistant materials in air plasma freejets, radiation measurements were performed at the three positions around ablating silicon carbide test piece in the air plasma freejets, namely just upstream point of the tip of the ablating test piece, side point just off the surface of the test piece, and a point in the ablation gas at a distance from the flow axis. In each point, characteristic continuum radiation, atomic Si lines, OH molecular bands, and CN molecular bands were observed in common.

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This paper studied control of separated flow over an NACA0015 airfoil by a single dielectric barrier discharge (DBD) plasma actuator installed at the leading edge using large-eddy simulations with high-order accurate and high-resolution numerical scheme. A chord-based Reynolds number of 260,000 and an angle of attack of 18.8 degrees were considered. A phenomenological DBD plasma-actuator model was employed to provide the spatial body force distribution. The unsteady operation so-called a burst mode actuation was introduced and two burst frequencies of 1 and 6 with constant burst ratio of 0.1 were analyzed. Effects of the burst frequency on flow control performance were discussed in detail. Results showed DBD plasma actuator with burst frequency of 6 provided better control authority in comparison with the burst frequency of 1.

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In the present paper, a Nano-second pulse actuator is applied to a NACA0012 airfoil in the condition of Re = 63,000 (U∞=10m/s) and leading edge separation control capability of a Nano-second pulse actuator is investigated. Angle of attack is changed in pre-stall angle, post-stall angle and deep-stall angle. At pre-stall angle, nano-second pulse actuation can move the reattachment point to upstream direction and shorten the separation bubble. This suggests that the nano-second pulse actuation can enhance turbulent transition of shear layer. At post-stall angle and deep-stall angle, higher peak voltage is more effective for separation control, though actuation of x/c=0.1 at the deep-stall angle has no capability for separation control at any peak voltage. Comparing the controlled cases at post-stall angle and deep-stall angle, the appropriate repetition frequency is different between the cases.

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We computed the velocity and temperature field at elbow in circular pipe flow using RANS model. The results are compared with the values measured by experiments. Geometry factor defined by the ratio of mass transfer in elbow and straight pipe is discussed. We also discuss how accurately the point electrode can measure the mass transfer rate in complicated flow field.

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Flow Accelerated Corrosion (FAC) is one of the issues to be noticed considerably in plant piping management. For the integrity and safety of the plant, it is important to clarify the wall-thinning and thinning rate due to FAC in pipe wall inspection. From previous study, FAC can be predicted by mass transfer coefficient and the coefficient was measured in the pipe behind the orifice under the turbulent condition by the numerical simulation and electrochemical method. In a plant, however, the pipe is connected complicatedly and complex flow may raise the risk of FAC. In this paper, we study mass transfer coefficient behind the orifice, which is located in the downstream of bend pipe. The mass transfer coefficient is evaluated by the numerical simulation through the analogy of heat transfer, and it is compared with the experimental data measured by the electrochemical method.

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The micromixer, which has a rotor with a curved channel, is studied experimentally. The Taylor-Dean 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 parameters concerned are the Dean number De and the Taylor number Tr. 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 ? 0.1Tr. This tendency appears more strongly if aspect ratio is large. And then we have confirmed the occurrence of reversal of the mean axial flow.

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Ice accretion is the phenomenon that super-cooled water droplets impinge and accrete on a body. It is well known that ice accretion on blades and airfoils leads to performance degradation and has caused severe accidents. One major cause of accidents due to ice accretion is supercooled large droplets (SLD). In this study, we apply a SLD model to a rotor blade of a jet engine under an icing condition, and the numerical results with/without the model are compared. We confirm that with the model, the volume of ice near the hub is larger than the result without the model. Through this study, the influence of the SLD icing model in a jet engine is numerically clarified.

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Swirling flow often accelerates FAC(Flow accelerated corrosion) that is one of pipe wall thinning.Parameters of FAC can be evaluated by the mass transfer rate. In previous studies,we confirmed that the maximum value of mass tranfer rate is increased by swirling flow. But we do not clearly understand the relationship between mass taransfer rate and flow field. In this study, we simultaneously measure taransfer rate and velocity, and then caluculate space-time correlation. When the swirling flow goes into the orifice, we observe that large correlation occures not only in u and v but also in V? component.

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Flow accelerated corrosion (FAC) is one of the important topics of interest associated with wall thinning phenomena in an aged power plant. For the reliability and the safety of operating nuclear power plant, it is necessary to clarify the process of wall thinning due to FAC. From the previous study, it is expected that FAC can be predicted by measuring mass transfer coefficient, k. However, the distribution of k in the bend pipe has not been investigated experimentally. We measured mass transfer coefficient in the bend pipe under turbulent condition. We found that the position of maximum value of mass transfer coefficient is not changed by Re number. We also found that the fluctuational frequency of maximum value of k is higher than the fluctuational frequency of k at straight pipe condition.

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Since 1980, TOTO has developed water jet technology of washletR washing human private body parts. Main stream of these developments has been conserving water. Recently we have developed a new fluid device which can reduce water 600ml/min to 430ml/min while wash feeling is remained. This fluid device uses a difference of density between water and air. Device has an orifice for fast main flow and a small room in downstream of orifice. In the small room, water and air make two different modes; one decelerates velocity of main flow, and another keeps it unchanged. Periodic two modes induce a phenomenon that fast flow catches up with slow flow until getting to human body and grows a large water cluster. A feeling of these large clusters is stronger than normal, constant flow because forming large clusters means that kinetic energy of water is concentrated and human body tend to feel an instant, large impulse.

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Heat transfer and pressure characteristics of two-dimension offset jet of fully developed flow were investigated experimentally. Flow visualization for the same flows was carried out using the high speed camera. The Reynolds number Re was changed in 1.5 X 103 to 7.0 X 103, and the offset ratio H/h was changed in 0.5, 1.0 and 1.5. The result shows that rolling up vortices appear downstream of the reattachment point. Two peaks exist at the Nusselt number distribution of the laminar flows with H/h=0.5 and 1.0. The 1st peak appears near the reattachment point of a jet flow, and 2nd peak appears in the neighborhood which vortices eject from the wall.

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We simulated multicomponent gas flow in a mock containment vessel using open source CFD code "OpenFOAM". Steam condensation model is implemented in multicomponent gas flow solver developed with OpenFOAM. In this condensation model, the amount of condensated water on wall is calculated by mass flux of the steam coexisting with noncondensation gas. We calculated two test cases; helium and nitrogen gas flows in vessel, and steam and nitrogen gas flows in duct with condensation.

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An experimental study is carried out for dividing flow through 90° T-junction of square cross-section. The Reynolds number based on the mean velocity at the main channel and the hydraulic diameter ranges from 1.3 X 103 to 2.0 X 104. The flow rate ratio (ratios between the flow rates in branch and main channel) is set at 0.2, 0.4, 0.6 and 0.8. The results show that the loss coefficient of branch channel increases with the increase of flow rate ratio, decreases with the increase of the Reynolds number. The empirical equations for loss coefficient are determined by the analysis of the experimental data. The velocity vector are measured by a PIV system to clarify the fluid flow characteristics .

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New experimental data and new equation of friction factor in a fully developed turbulent pipe flow at high Reynolds number is presented in this paper. The experiments are performed using the water flow test facility for high Reynolds number in NMIJ, AIST. The Reynolds number range examined is from 4.69 X 104 to 1.77 X 107. The experimental friction factors are smaller than those by the Prandtl equation in high Reynolds number region, Re>1.0 X 105 and those do not agree with the previous experiment. Finally, new equation for the friction factor based on the experimental results is proposed.

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Pressure distributions of a swirling flow generated between two parallel disk shape plates were measured for two kinds of inlet flow conditions. The experiment was performed at low Reynolds numbers (Re <100) to simulate the practical operation in a disk shape planar-type solid oxide fuel cell (SOFC). When a swirling flow was fed into the disk channel, the static pressure reduced in whole regions of the channel. However, a positive pressure gradient normal to the current collector surface was observed regardless of the inlet flow condition. A swirling fluid motion was examined by using an equation of motion, and then we confirmed that pressure gradient normal to the current collector surface was produced to maintain the swirling flow in the disk channel.

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Numerical simulation is carried out to investigate the destabilizing process of a boundary layer. The boundary layer is destabilized by a combination of streaky structures and short-duration jet ejection. Deformation of streaky structures can be observed when the jet velocity is high. However, the onset of turbulence cannot be observed in the computation.

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Numerical investigation of the flow around rectangular wings placed near the cavity is studied by the immersed boundary method with body force type. Two cases of angle of attack, θ=90° and θ=60°, were tested with Re=1000 based on the width of the rectangular wing and inlet speed. In the case of θ=90°, the asymmetric vortical structures grow at the downstream, and the backflow region is found behind the wing. In the case of θ=60°, however, vortical structures become weakened and backflow region at the back of the wing disappears mostly due to the blowing from the cavity.

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An upswept aft body of vehicles can improve their aerodynamic performance. In order to study the effect of the upswept aft body, we examine flows around a two-dimensional rectangular cylinder with an upswept aft section in ground effects by means of RANS (Reynolds-Averaged Navier-Stokes) simulations. It is shown that an aerodynamic downforce increases due to the upswept aft section, since the flow between the cylinder and the ground is accelerated by a diffuser effect. Interestingly, the diffuser effect does not influence the total drag so much, because the drag increase of the upswept aft section is canceled by the drag reduction of a rear section of the cylinder.

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The effect of wheel geometry on the total aerodynamic drag of a road vehicle was investigated. The relationship between the aerodynamic drag of a full vehicle and a single wheel detached from the vehicle was first investigated in wind-tunnel measurements, and positive correlation between them was obtained. Then the mechanisms of generating the aerodynamic drag were investigated and their similarities were confirmed through large-eddy simulation. These results suggest the possibility of estimating the effect of wheel shape upon the drag coefficient of a full vehicle through isolated wheel aerodynamics.

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Compression waves are generated and propagate through a tunnel when a high-speed train enters a tunnel. These waves affect a tunnel wall and ride comfort. These pressure changes are complex when two trains pass by each other in a tunnel. Therefore, it is necessary to predict these pressure changes. We did 3-dimentional large eddy simulation that takes account of the viscosity. Thus, we predicted compression waves, expansion waves, pressure changes at a tunnel wall and fluid force acting on a train under condition of the two trains passing by in a tunnel.

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We have investigated the behaviors of rod-like hematite particles in a simple shear flow as well as in an applied magnetic field, in order to clarify the dependence of the negative magneto-rheological effect on particle aggregation and orientational distribution of particles. The present Brownian dynamics method has a significant advantage that it takes into account the spin rotational Brownian motion about the particle axis in addition to the ordinary translational and rotational Brownian motion. In contrast to the ferromagnetic rod-like particle that exhibits a single-peak-type orientational distribution, the present hematite particle has a linear-peak-type distribution with a much more gentle profile. However, this slightly reformed distribution makes a significant influence on the negative magnetorheological effect.

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