The three hot-wire probe has been developed to make the simultaneous measurement of concentration and two velocity components for CO_2-air mixture. In this method, two hot-wire probes (X type hot-wire probes) with low overheat ratio and one hot-wire probe (I type hot-wire probe) with overheat ratio used in the past work by Chassaing (1979) have been used. The values of the instantaneous concentration and two velocity components can be determined from the output voltages of three hot-wire probes. The measurements have been performed in case of the CO_2 jet in the grid turbulence. The experimental results showed that profiles of axial turbulent scalar flux and joint-p.d.f. of two velocity components and concentration agree with the past other data.

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A method of obtaining an optimal calibration curve for Sprit Film Probe was presented. This probe is an effective velocity sensor in the turbulent flow with reverse-flow. However, an optical calibration method for this probe has not been ascertained yet, because of complex heat interaction and existence of split line on a hot film. As the resalt of this study, it was found that exponential functions based on King's law which were obtained each probe angles of attack were applied to calibration functions that express the relation between heat radiant rating and velocity.

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In this paper, we discussed measurement system of LDV with high data rate for low noise wind tunnels. In order to improve the data rate of LDV system and reduce the turbulent intensity in the wake of the seeding system, water mist was provided at the settling chamber of the wind tunnel. The seeding unit was therefore installed into the pressurized seeding chamber which was constructed outside of the wind tunnel test-section. To avoid sound reflection, test sections of low noise wind tunnels are fabricated with porous materials, forward scattered LDV is difficult to be made use of. Thus, the authors compared the data rate of forward scattered LDV with than that of backward one and discussed possibility of utilization of forward scattered LDV with low noise wind tunnels. As a result, the data rate of LDV system was improved from 300Hz to 10kHz with the pressurized seeding system and forward scattered LDV. It revealed that the proposed technique is appropriate for measurement of flow field in which aerodynamic sound must be concerned.

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The flow around a torus has a complicated three-dimensional structure. We researched the secondary-flow structure of the wake behind the torus by using a five-hole pitot tube and a hot-wire probe, in which two kinds of tori with different diameter ratios or solidity are set in a uniform flow with zero inclination and an oblique posture. For the torus with zero inclination, there were two modes of flow structure according to the diameter ratio, while for the torus set with an oblique posture, the structure of the wake changed with respect to the oblique angle in a complicated fashion.

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We observed liquids dripping out of an aperture at low Reynolds number using CCD camera, and measured the mass of a drop and the velocity of falling drops, and estimated the first norinal stress difference. The data of the first normal stress difference obtained by the present method was compared with the data by the jet thrust method. The range of Reynolds number was 1∿200 for the present experiment, but it was in the order of 1000 for the jet thrust method. The solution used in this experiment is a mixed-solution of Ethoquad O/12 and sodium salicylate. The validity of the present method for measuring the first normal stress difference was confirmed.

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When a fluid pushes a more viscous fluid in a thin parallel channel, the surface between two fluids forms finger-like patterns, which is called "viscous fingering". The growth of viscous fingers was obserbed by using polymer fluid and Newtonian fluid as a more viscous fluid. This experimental results showed that the relation of the finger tip velocity and the pressure gradient in the case of polymer fluid is unlike that in the case of Newtonian fluid. In addition, in both cases the tip velocity of was a function of the local pressure gradient near the surface rather than that of the average puressure gradient.

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Influence of wall effect for measurement of planar elongational viscosity by 4-roll mill flow cell was investigated. Elongation rate distribution along laser beam for measuring flow-birefringence was become clear by flow visualization. It was shown that the degree of two-dimensionality was decreased by the bottom wall effect and the non-uniformity of elongational distribution makes an error on the result of planar elongational viscosity. The conduit for light was attached on the bottom wall to reduce the wall effect and it was shown that using the conduit can reduce the error of measurement of planar elongational viscosity.

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A square cross-section reservoir attached with a capillary on its bottom is used to investigate the influence of the upper wall on start-up behavior of viscoelastic capillary entry flow. The viscoelastic flow shows remarkable transient behavior such as over shoot of velocity and flow rate before they attain their respective terminal values. The upper wall markedly affects the flow pattern and enhances the entry pressure loss.

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In the present paper, we measured the filament length between the tip of the coated rod and the liquid surface when the filament broke in the dip coating process in the manufacturing of capsules, and examined the filament length dependence on the rheological properties of coating liquids and withdrawal velocity. The coating liquids were aqueous solutions of syrup (Newtonian liquids) and mixture liquids of aqueous solutions of syrup and polyacrylamide (polymeric liquids). Consequently, it is found that a large withdrawal velocity brings a shorter time at the filament breakage in Newtonian liquids regardless of their shear viscosities, while a large elongational viscosity causes a large filament length in polymeric liquids. The large withdrawal velocity was ineffective upon the reduction of the breakage time of the filament in polymeric liquids. Therefore, the use of polymeric liquids reduces the efficiency of manufacturing in dip coating process.

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It measured the frictional resistance which is generated in the flow between two disks, one disk with the slits is rotating and the other fixed. Aqueous glycerin solutions are used as Newtonian fluids, and aqueous glycerin solutions adding polyacrylamide (Separan) are used as viscoelastic fluids. It was found that the moment is mainly concerned with the viscosity and the disk speed for Newtonian fluids, but for viscoelastic fluids it takes values greater than those estimated with the viscosity possessed by the solutions. Moment coefficient Cm is correlated with Reynolds number for Newtonian fluids, but larger for viscoelastic fluids than for Newtonian fluids. Also, as for the influence of the slits, the tendency which is different in Newtonian fluids and viscoelastic fluids appeard.

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Surfactant molecules form a wide variety of micelles in the quiescent solution and under a certain condition of the solution shear flows induce micellar networks called as SIS. In the present study surfactant solutions (CTAB+NaSal), which exhibited SIS, were applied to pressure-driven flows through a capillary and the development of the flow was examined through the measurement of a pressure distribution along a capillary axis. The convex profile of the pressure along the capillary axis was confirmed at high shear rates where the SIS occurred. At the same time, the shear-thickening in apparent viscosity become remarkable far downstream of the capillary entrance.

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Development behavior of fluctuating velocity of surfactant solution in a duct has been studied experimentally. The concentration of surfactants was kept constant at 1,000ppm, mean velocity at 0.78m/s and fluid temperature at 15℃. Using LDV, the fluctuating streamwise velocity distributions at six cross-sections, which are ranged from 28 to 112 times of hydraulic diameter of the duct, were measured. From the results, the fluctuating structures of surfactant solution flow are observed to have the different structures from that of turbulent water flow in the developing field. The wavelet analysis reveals the fluctuation of surfactant solution flow is characterized by periodicity rather than irregularity around the position where the fluctuation intensity takes a peak value. The size of fluctuation structures is also found to become small in the near wall region below the peak, because the viscosity field is developing near the wall.

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Effects of a drag reducing surfactant solution on the flow around a circular cylinder were investigated in a Reynolds number range 200<Re<5000. In this experiment, the drag coefficient on a circular cylinder in surfactant solution was measured by the means of a load cell. In addition, we conducted the flow visualization experiments. For lower Reynolds number, the data of drag coefficient showed higher values for the surfactant solution than those for water. In the case of the cylinder diameter of 20mm, drag reduction occurred when the Reynolds number reached about 3000. It was seen that the drag of a circular cylinder in surfactant solution increased with Reynolds number in Re<3000 for d=20mm by the existence of the low velocity zone around the cylinder.

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Performance of a centrifugal pump when handling surfactant solutions was measured experimentally. The effects of the concentration and temperature of surfactant solutions on a pump performance were investigated. It was clarified that the pump efficiency with surfactant solutions increased comparing that of tap water, and increased with an increase of surfactant concentration. The total pump head increased with an increase in the surfactant concentration, however the shaft power decreased with a decrease in the rotational speed of an impeller. The pump efficiency is dependent on the surfactant temperature, and there is a most suitable temperature which maximizes the efficiency.

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Surfactant molecules form bilayer lipid membranes (BLM) in the water. Vesicles and red blood cells have the same property as the BLM. Both of them have fluidity and shape fluctuations. It is also well known that both of them have no surface tension. We numerically study the shape fluctuation phase transition of a model of vesicles and see how fluidity influences the phase transition.

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Flow simple low-molecular fluids such as water or glycerin solutions, which are Newtonian fluids, fluid slip at the solid boundary is ordinary negligible, and it is well known that the calculated result obtained under the no-slip boundary condition agrees well with the experimental results. On the other hand, recently the possibility that some hydrophobic walls produced by the development of coating materials has been realized. The objective of this study is to clarify the effect of fluid slip on the drag reduction of a duct or a sphere with a highly water-repellent wall. Consequently, the drag reduction occurs in laminar flow range at the highly water-repellent wall with many fine grooves, and the formation of the gas-liquid interface in the grooves plays a very important role for the occurrence of the apparent fluid slip.

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In order to clarify laminar drag reduction and the slip velocity on a hydrophobic surface, the pressure loss of a rectangular duct was measured applying the six kinds of the wall surface qualities to duct inner wall. Test wall surfaces were the hydrophobic or the hydrophilic micro V-groove surface, rectangle micro groove surface and smooth surface. In the case of hydrophilic surface, a drop of water was remarkably extended by the effect of the surface ruggedness, and hydrophilicity was emphasized. On the contrary, in the hydrophobic surface, the water droplet became more spherical by the surface ruggedness, and the hydrophobicity was emphasized. From the result of the pressure loss measurement, it was clarified that the drag reduction was not occurred in all test surfaces.

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The effect of texture, defined as periodic microstructure, on dynamic wettability was investigated. Various textures that consist of lattice-aligned pillars of 1 to 64μm in diameter and 0.1 to 8μm in height were prepared with dry etching of silicon substrate. It was found that there are two kinds of tendency. In case the air is trapped between the pillars, the narrower pillar-pitch makes the wettability lower. On the other hand, in the case the air is not trapped, the higher and narrower pillar-pitch makes the wettability higher. Thus, by choosing appropriate pillar height and pitch, the wettability can be controlled.

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A real fluid does not slip at the surface of a solid. Most experimental results and simulations of a Newtonian fluid satisfy the condition. It, however, has clarified experimentally that a slip velocity exists on a hydrophobic surface. In this paper, a model that a fluid slip exists on the surface where a gas liquid interface is simulated. And a new wet boundary condition for a hydrophobic property has been proposed. As a result, if a thickness of the interface is fully smaller than the surface roughness, this analysis is an effective method for fluid slip at a hydrophobic surface.

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Bio-fluids flow in Bio-MEMS (Bio-Micro-Electrical-Mechanical-Systems) or μTAS (Micro-Total-Analytical-Systems) chips, which are recently attracted, have some problems such as deformation of bio-molecules and aggregation of bio-molecules to a wall. Such problems can cause blockage or breakage of the chips. In this work, we aim to evaluate biofluids flow on a hydrophobic surface for preventing aggregation of bio-molecules. Concretely, relation between pressure drop and volumetric flowrate was investigated. While flow in the hydrophilic micro-tubes with 100μm order for diameter agreed well with the conventional Hagen-Poiseuille equation, results for hydrophobic micro-tubes show that volumetric flowrates was larger than analytical value of those. For biofluid flow, the aggregation of bio-molecules could lessen the effects of increasing volumetric flowrates. The evaluations of aggregation on the hydrophobic surface for biofluid are now on investigating.

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A startup flow of polymeric liquids was numerically simulated using a stochastic approach. In this approach, the FENE dumbbell model was applied and the polymer stress was computed by the stochastic calculation of connected vectors of the dumbbell. The startup flow in a 2 : 1 : 2 abrupt contraction-expansion channel that consists of two parallel channels connected by a slit. The effects of the slit length and the Weissenebrg number were investigated. Temporal change in the velocity and stress fields are analyzed together with microscopic predictons of molecular orientation. It is an advantage of the present method to analyze the flow behavior with macroscopic information.

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The properties of polymer melts are different from those of monomer materials because polymer materials have crystalline and amorphous regions. In addition, polymer melts have elasticity as well as viscosity. Therefore, the viscoelasticity, crystallinity and temperature of polymer melts must be included in the accurate simulation of melt spinning process for crystalline polymer. In this study, we simulated the melt spinning process of Nylon-6 by using the streamline-upwinding finite element method. The non-isothermal Phan-Thien Tanner model proposed by Sugeng and Phan-Thien was employed as a constitutive equation. We investigated the distributions of temperature and crystallinity on the free surface of the filament, and the filament diameter. Calculation results were almost independent of gravity. The primary normal stress increases and the filament diameter decreases with an increase of take-up speed. The filament diameter obtained by the non-isothermal flow simulation is smaller than that by the isothermal one, and the filament diameter depends on the crystallinity. The shape of filament of purely viscous fluid is the same as that of viscoelastic one.

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The modified singular/decoupled finite element method for the die-swell flow simulations of viscoelastic fluids was investigated. The special r^<-0.5> type singular elements (where r denotes the distance from singularity) in a small core region around the singular point have been applied for the elastic stress and pressure fields, and the special r^<0.5> type singular elements for the velocity field; and we have intentionally removed all of nodal points from the singularity. When discretizing the constitutive equation, the "1x2 subelement scheme" was introduced to the elastic stress in the singular element region, associated with 8 nodal special shape functions, i.e., the special r^<-0.5> type shape functions in the radial direction and bilinear shape functions in the azimuthal direction. It was found that the modified singular FEM yielded the more smoothed and rational asymptotic behavior in the vicinity of the singular point than the previous singular FEM.

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To investigate the influence of food rheology on aspiration, a swallowing flow was numerically simulated. A simplified 3-D throat model was introduced. Increasing in the bolus viscosity, the leading edge velocity is reduced. The remarkable reduction in the velocity is obtained for the bolus viscosity higher than 8.72×(10)^<-2>Pas. The bolus with the higher viscosity induces higher driving pressure to produce the swallowing flow. The bolus viscosity 0.872Pas gives the remarkable pressure increase, which would make swallowing harder. The dependency of viscosity on the shear rate was discussed using a power law model.

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Water mist is one of the digestives noted for a new generation fire suppression system, and it has a lot of extinction effects. In this paper, the effect by the evaporation of droplets was considered, and the gas-droplet flow was computed for analysis of the water mist fire control. Especially, the cooling effect of water mist was discussed with changing the diameter of droplets. It was found through our computation that the distribution of droplets and the cooling effect change significantly according to the droplets diameters, and we conclude that the diameter of droplet is important parameter which determines the extinction effect of water mist fire suppression system.

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Recently porous materials are candidates as filters in order to filtrate or separate various materials under high temperature environment such as Diesel Particulate Filter (DPF) or membrane filter. Filtration or separation is achieved when mixed medium flows through porous materials. To increase the operating efficiency, the initial pressure drop across porous materials should be minimized. This study is phenomenologically approached about modeling of pressure drop for porous materials by using image analysis and fluid dynamics. By introducing new parameter called "Length of capillarity", pressure drop across porous materials and complex structure of porous materials are mutually correlated.

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This paper presents the rheo-optical experimental result of flow through a slit. We used Mach-Zhender interferometer. Distilled water was used as test fluid, and made to flow through a two-dimensional slit, by using a pump of syringe type. Interference fringes were recorded with a digital video camera, for the flow in the range upstream and downstream of the slit. It was observed that the interference fringe changes especially in the downstream even for the distilled water and the change in interference fringes is sensitive to the change in temperature of the test fluid.

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In order to clarify the effect of viscoelastic properties of polymer solutions on the E.O.R, the flow of viscoelastic fluids penetrating into the Newtonian fluid in the axisymmetrial undulating channel was examined numerically. The viscoelastic fluids used in calculations were the Giesekus fluids with a different property of shear viscosity. In the results of this numerical calculation, it is found that the shape of the interface between the both fluids is closely connected to the viscoelastic effect.

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The flow behavior of polymer solutions among cylinders in a rectangular channel has been studied by means of flow visualization and particle image velocimetry. Cylinders are placed asymmetrically in a channel and there are narrow channels and wide channels formed by the offset positioning of circular-cylinder barriers. The fluids used here are polyacrylamide (PAA) 300ppm solution and Xanthan gum 800ppm solution, which show nearly the same shear viscosity. In this study, attention has been paid to the upstream region of the first cylinder. Owing to high extensional viscosity at high extensional rate, PAA solution cannot find its way into the narrow channel. In addition, difference of flow pattern in z-direction has been studied and extraordinary flow has been found that high velocity region appeared near the side wall in the upstream section.

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Flow of viscoelastic suspensions with bamboo or glass fibers contained between a rotating inner hemisphere and a stationary outer sphere is studied experimentally. In the present investigation, relatively low-concentration polyacrylamide-water solutions with bamboo fibers are used as test fluids. In this report measurements of torque and thrust are presented, and which showed strong dependence on Reynolds number, a gap ration, for various concentration of the fibers.

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We have investigated flow characteristics of concentrated suspensions of rough particles under large amplitude oscillatory shear. In the transient response after the shear reversal, the suspensions of rough particles show smaller transient deviation from the purely viscous response than that of sphere, and require larger strain to rearrange a microstructure of the particles. This would be related to a lower aligned microstructure generated in the suspensions of rough particles. Lower apparent viscosity in quasi-steady flow after the transient response is estimated in higher frequency oscillatory flow.

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We have investigated structural rearrangement caused in a transient Couette flow of an aqueous solution of hydroxypropylecellose (HPC). After a pre-shear flow, a subsequent flow starts in a different direction. After several strains in the subsequent one, a streak, generated in the SALS motion picture, became clear and sharp, and its direction was gradually turned to the final one. Moreover a periodic nondirective light was simultaneously observed. It was considered that the molecular orientation was gradually aligned and turned, and the synchronized tumbling motion was also generated. Then the tumbling period was getting long and an aligned structure was finally generated.

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An experimental investigation has been made on the breakdown and spacing of magnetic fluid droplets by a vertically oriented magnetic field. When no magnetic field exists, a magnetic fluid droplet lying in a vertical gravitational field on a horizontal plane takes an equilibrium shape. When a vertical magnetic field is applied and its intensity increases, the droplet extends vertically. If the magnetic field intensity exceeds a critical value, the droplet breaks down into two droplets. We show these phenomena experimentally and compare with the surface phenomena of a magnetic fluid pool.

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A damper system using MCF (Magnetic Compound Fluid) that is a mixture of MF (Magnetic Fluid) and carbonyl iron particles is proposed. With applying MCF to damper system, there is no sedimentation of magnetic particles (iron) that mixed with magnetic fluid so that the attenuation characteristics of the viscous damper would be kept without outer magnetic field. In this study, particular attention is paid for hysteresis characteristics of MCF with applying magnetic field so that the effect of the method of applying outer magnetic field to the damper is considered. As the results, it is found that there exists certain difference on the method of applying outer magnetic field, and it is noted that the hysteresis characteristics woulld be useful to change attenuation characteristics with applying outer magnetic field to the damper.

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In the present experiments two arrangements of the electrodes fixed on the inner surface of the circular tube are developed. One is that the four pair of the electrodes is fixed to add the voltages in the peripheral direction. The other is that the electrodes are lined up along the inner surface to add the voltages in the axial direction. The pressure drops are measured when the liquid crystal mixture made of some kinds of the nematic liquid crystal flows in the circular tubes for the constant flow rates. When the voltages are applied on the liquid crystal mixture and removed, the pressure responses of the inlet of the circular tube are measured with the pressure transducer. The diameter of the circular tube is 1.0mm. The isotropic-nematic transition is 90.0℃ and smectic-nematic transition is -44.0℃ for the liquid crystal mixture. The open-loop test facility with the liquid crystal is set in a pyrostat to keep the temperature constant.

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We have examined a new method of flow rate evaluation from the flow image of liquid crystal in a minute ER channel with stripe-patterned electrodes. We found a good correlation between the standard deviation of brightness estimated with the polarized image and the flow rate. Particularly, the channel with an alternate stripes electrode pattern, which generates electric fields parallel to the flow direction, was useful for the wide range of flow rate.

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The Leslie-Ericksen continuum theory has been used to study unsteady behaviors of the director and backflow induced by the motion of the director when a magnetic field is imposed on a nematic liquid crystal placed between two parallel plates. Twist angle, which is one of the boundary conditions, is selected as a computation parameter. It is confirmed that backflow is induced by a magnetic field through the reorientation of the director to the direction of the magnetic field. The maximum value of the backflow is about 0.09mm/s. It is found that the velocity profiles become asymmetric and the bulk flow rates become non-zero values, depending on the twist angle. Also, the experimental confirmation of the backflow has been performed by observing micro-particles which are suspended in the liquid crystal.

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Fundamental research on flexoelectric effect of the nematic liquid crystals has been performed numerically using the Leslie-Ericksen continuum theory. The liquid crystal is confined in between parallel plates. The lower plate is fixed, while the upper one moves along x-direction. Once shear flow is applied, the molecular orientation field is distorted by the flow. Then flexoelectric polarization occurs between the upper and lower plates. Two types anchoring conditions are adopted at the plates (i.e. strong anchoring for lower boundary and weak for upper boundary). Then, the flexoelectric polarization has been estimated from the calculated molecular orientation field. The flexoelectric polarization along y-direction increases with time.

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The diffusion of matter in compound round jet is simulated by a three-dimensional particle method. It is shown that the concentration distribution yielded by the three-dimensional vortical flow is in good agreement with the experimental one obtained by the flow visualization. The mean concentration is confirmed to be in the self-preservation state.

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Flows about a ball valve are simulated by the discrete vortex method. The flow is assumed to be axi-symmetric and formulated by a set of circular vortex rings. The formulation is performed by the Stokes stream function and the elliptic functions. Free vortices move due to induced velocity from other vortices, affect of viscosity diffusion and that by themselves. The self-induced velocity is evaluated by assuming that the vortex ring has finite-size core. The duct and the ball surfaces are also represented by the vortex rings. The wake of the ball is successfully simulated.

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Vortex method provides grid-free Lagrangian simulation of unsteady, high Reynolds number and vortical flows without any conventional time-averaged turbulence models. Recently, vortex method is expected to extend to analyses of multiphase flows, because it is able to comprehend the interactions of particles with the vortex structures. However, there are few applications of vortex method for the internal unsteady multiphase flows, though many industrial flows are internal. For that purpose, we tried to apply the special combination of vortex method with particle trajectory tracking method to the internal unsteady two-phase flows of high Reynolds number. As the result, we successfully simulated the unsteady separation that occurred due to the influence of the adverse pressure gradient and the interaction between the shear layer and the wall. Calculation results of fluid flow field showed a good agreement with available experimental data. The results of the mixing process of the particle showed that large-scale vortices dominate the particle motion. The present study clarified the applicability of the completely grid-free Lagrangian-Lagrangian simulation to the internal unsteady multiphase flows.

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This paper describes the work of development of a virtual two-dimensional wind tunnel using a vortex element method carried by the authors group, explaining the mathematical basis of the method and structure of the virtual wind tunnel. Following the development of an advanced vortex element method, the authors proceeded to development of a two-dimensional wind tunnel as the first step. The two-dimensional wind tunnel works on a personal computer, and it has features that a user can begin immediately unsteady calculation of a flow around multiple bodies in a uniform flow without any grid-generation work. In this paper, typical results of two-dimensional and unsteady calculation of flows around an aerofoil are explained.

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This paper describes recent works of practical applications of vortex element methods in the engineering field, carried by the authors' group, explaining the mathematical basis of the method based on the Biot-Savart law. It is pointed as one of the most attractive features of the vortex method that the numerical simulation using the method is considered to be a new and simple technique of large eddy simulation, because they consist of simple algorithm based on physics of flow and it provides a completely grid-free Lagrangian calculation. As typical results of virtual operation, the internal flow of a mixed-flow pump stage, unsteady flows around the GTS tractor-trailer including meandering motion are explained.

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Flow field in porous media is simulated using the Lattice Boltzmann method (LBM). The d2q9 model for 2D simulation and d3q15 model for 3D simulation are used. The porous structure is simplified to insert obstacles with square shape in the 2-D or 3-D duct flow. These obstacles are placed randomly to keep the same porosity. To change the flow characteristics with any roughness in this model, the different number and size of obstacles are used. Distributions of velocity and pressure are discussed with the Ergun equation in the dimensionless form to show the validity of our simplified model.

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The lattice Boltzmann method for multicomponent immiscible fluids is applied to the simulations of wetting dynamics. The wetting is introduced by using the wetting potential proposed by Briant et al. To confirm the validity of the model, we investigate the static contact angle of a droplet onto a wall, and compare it with Young's equation in good agreement. Also, we apply the method to the flow in a micro channel and find that the interface is advanced by a capillary force.

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Simple and practical finite volume scheme based on the quadrilateral elements is applied to Lattice Boltzmann Method for two-phase flows simulation. The numerical simulation results of Poiseuille flow and of two-phase flows indicate the applicability of the finite volume method to Lattice Boltzmann Model. Simulations of droplets dynamics between curved planes are carried out, showing the flexibility to fluid flow simulation in a wide variety of regions which contain arbitrarily shaped boundaries. All simulation results show smooth density distributions in regions including various mesh sizes.

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Three-dimensional direct numerical simulation of aerodynamic sound by the finite difference lattice Boltzmann method (FDLBM) is reported. We use a new lattice BGK compressible fluid model that has an additional term and allow larger time increment comparing the conventional FDLBM, and also use a boundary fitted co-ordinates. We have succeeded in capturing very small pressure fluctuations in a uniform flow over a circular cylinder. They were generated with same frequency of Karman vortex street. We can also succeed to detect the aerodynamic sound which is generated by a three-dimensional body and propagates in radial direction. We clarified that we can calculate the aerodynamic sound directly using by the finite difference lattice Boltzmann method.

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In this paper, three-dimensional numerical simulation around a calculation model of the part of vehicle's front pillar (wedge-box) by the finite difference lattice Boltzmann method (FDLBM) is reported. We use a new lattice BGK incompressible fluid model that has an additional term to manipulate a viscous term. As a result, we have confirmed the generation of the spiral flow by the sidepiece of wedge box, and captured the reattachment line of the spiral flow.

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The lattice Boltzmann method (LBM) gives unphysical results, in particular, near the wall boundary when arrangement between the wall and the lattice is asymmetric. The authors proposed a method which made set of the lattice velocities rotate randomly at every time step on each lattice node to overcome the problem. This method holds mass, momentum and Boltzmann's H-function conserved for distribution functions of each lattice velocity size, and thereby it can be applied only to the 2-dimensional 9-velocity (D2Q9) model. In a present report, this method is applied to the other model with an appropriate division of the mass conservation and it is shown that it works but keeps a problem of giving inaccurate flow properties observed in the D2Q9 version. However, if one selects the collision frequency of unity, the precise results, which agrees with previous results very well, can be obtained with this method.

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The Rayleigh-Benard convection is simulated numerically using the lattice Boltzmann method. Parallel calculations are performed and flow patterns are observed in a rectangular box with an aspect ratio ranging from 2 : 2 : 1 to 6 : 6 : 1. The heat transfer rate is estimated in terms of the Nusselt number. The dependency of the Nusselt number on the Rayleigh number is shown to agree well with that obtained by the two-dimensional calculations of the Navier-Stokes equations. It is found that several roll patterns are possible and the heat transfer rate changes according to the flow pattern.

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