This paper describes a CFD method based on the Boltzmann equation developed for low Mach number micro flows. Reliability and flexibility of the methods are demonstrated for flow simulation about micro channels and micro spheres at the Mach number range from 0.0001 to 0.1 and the Knudsen number range from 0.01 to 0.1. Reliable results without any fluctuation are obtained even for the flow Mach number of 0.0001. Fully developed velocity profiles of the micro channels well agree with those of slip flow model. The drag coefficients of the micro spheres are compared with those of continuum and slip flow theory. It is confirmed that the method is a good tool to analyze micro gas flows.

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Application of Lattice Boltzmann Method (LBM) to micro-CFD is discussed. Incompressible 2-D and 3-D micro-chanenel flows are solved by LBM. The results are compared with those of the conventional Navier-Stokes equations. It is found that comparable results are obtained with less computer time in LBM. LBM is found to be an alternative tool to conventional continuum approach in CFD, especially for micro flow problems.

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Larege-scale molecular dynamics simulations were carried out in order to investigate the effects of surface adsorption on bubble dynamics. We observed a single vapor bubble rising with constant velocity under strong external field in liquid, which consists of 200,000 Lennard-Jones particles. In pure liquid, the flow around the bubble has non-zero velocity on the bubble surface, which is consistent with the slip boundary condition assumed in continuum fluid mechanics. When sufficient amount of model surfactants are adsorbed on the surface, the rising speed drastically decreases, and the flow velocity becomes almost zero on the bubble surface. The adsorbed surfactants are transported on the bubble surface and pile up on the rear end of the bubble.

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We have examined the molecular boundary condition of nonequilibrium interface to develop a kinetic theory of gas by using nonequilibrium molecular dynamics (NEMD) simulation and direct simulation Monte Carlo (DSMC). The NEMD shows that the velocity distribution of reflected molecules is different from the equation obtained for the equilibrium condition and the DSMC indicates that the molecular boundary condition for the reflected molecules plays an important role in the temperature jump at the interface.

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The microscopic investigation of the dynamics of surfactant molecules near the air/water interface is essential for the overall understanding of adsorption phenomena and the construction of a practical adsorption model. In this paper, by molecular dynamics method, we have simulated the adsorption of ethanol molecules from bulk water solution to pure interface. The calculated density profile along the axis vertical to the interface showed three distinct region; i. e. the adsorbed interface, the bulk solution, and the intermediate diffusion area. Counting the number of ethanol molecules included in the first region, we estimated the surface excess amount of ethanol at each time. In addition, using the autocorrelation function method, we estimated the adsorption flux and desorption flux at every 50ps. As a result we confirmed that the desorption flux monotomically increased with the surface excess increasing and accordingly balanced with adsorption flux at adsorption equilibrium state, while the adsorption flux varied in rather complicated style. We also finded the noticeable chage of the desorption collision dynamics just before the adsorption equiriblium establishment.

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As an approach to establishment of clustering from a liquid, I've Molecular dynamics simulation of clustering process from liquid droplet with adiabatic expansion, which is actually being used in the experiment. The method of changing into fragment with adiabatic expansion is being used for this clustering process. Molecular action inside liquid droplet was explained by simulating this, and compared with the principle of this method of clustering. Molecular binding around the surface of liquid droplet influenced whether clusters are formed deeply, and molecule action became what was different from that it was thinking about from the principle as a result.

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Dynamic behavior of small droplet was calculated by classical molecular dynamics method in order to investigate effects of nanoparticles on thermal properties of clusters and their evaporation. A benzene droplet including fullerene was employed in the present study. Lennard-Jones potential functions were used as intermolecular potetial functions. Number of cluster in the case of benzen system including fullerene was smaller than in the case of pure benzene system. In heating process, fullerenes have helped to make the size of clusters larger and the number of them smaller.

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We propose a simple polynomial basis-set that is easily extendable to any desired higher-order accuracy. This method, i. e. the CIP-BS method, is based on the Constrained Interpolation Profile (CIP) method and the profile is chosen so that the subgrid scale solution approaches the real solution with the constraints from the spatial derivative of the original equation. Thus the solution even on the subgrid scale becomes consistent with the master equation. By increasing the order of the polynomial, this solution quickly converges. The governing equation is transformed into the discretized form by taking scalar products with each basis function.

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Recent progresses of theoretical and numerical understandings of multibubble dynamics in a sound field are reviewed. In recent papers, we have pointed out that an unknown characteristic frequency exists in a system of gas bubbles acoustically interacting with each other, a frequency which reverses the pulsation phase of a bubble in the system without accompanying resonant response, and is named "transition frequency". Furthermore, we, based on transition-frequency analysis, provided an alternative interpretation of the sign reversal of the secondary Bjerknes force acting between pulsating gas bubbles, which can be either attractive or repulsive. Those findings have been well reproduced by the direct numerical simulation using an improved CIP-CUP method we have proposed. In the present paper, we mention several interesting points of this physical problem in the physical and numerical viewpoints.

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Numerical study was conducted on the axisymmetric swirling flows of viscous Boussinesq fluid in cylindrical containers with co-and counter-rotating end disks. Swirling flows are studied for the angular velocity ratio of end disks in the range of -1.0≦s≦1.0 with and without vertically stabilizing temperature differences. The side wall i* th*mally insulated. For the co-rotating end disks, the flows are well described by the classic similarity solutions when s ≅ 1.0. When s ≅ 0,the flow exhibits much studied vortex breakdowns depending on the Reynolds number and the cylinder aspect ratio. For the counter-rotating end disks, flow separation occurs on the side wall and recirculation zones are created. Under strong vertical temperature differences, layered structures appear for all values of studied in the meridional plane and conductive temperature distribution prevails Supression of azimuthal velocity component is noted at mid-height of the cylinder.

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Numerical study was performed for the vortex breakdowns in swirling flows driven by constantly rotating the top cover of cylindrical containers. Computation was done for the parameter range where steady axisymmetric flows emerge. By varying the grid resolution and by using the Richardson extrapolation, resolution independent solutions are obtained and flow state diagram was numerically constructed. Numerical results are compared with the experimental visualizations by Escudier and Roesner and a good agreement was observed. The present results are compared also with the previous study by Brons et al. for high Re, high aspect ratio cases. The comparison revealed some disagreement on some part of the bifurcation curves. Numerical solutions obtained in the present study might be used as benchmark solutions with which newly developed numerical methods may be tested against.

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In this paper, an inverse analysis method of thermal conductivity is proposed in functionally graded material plates (FGM plates) with the function of temperature control and thermal bending minimization. This method is based on piecewise nonlinear nonhomogeneous approximate method (PNNA method) developed to obtain accurate analytical solutions for the transient heat conduction problems in FGM plate with arbitrary variation in thermal conductivity through the thickness, and genetic algorithm (GA). The thermal conductivity in PSZ/SUS304 FGM plate with the function mentioned above is inversely determined. The curvature of thermal bending and the temperature distribution in the FGM plate with the thermal conductivity determined inversely are shown.

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This paper is concerned with the numerical treatment of one-spatial dimensional generalized piezothermoelastic wave propagations in piezoelectric plates subjected to thermal, electric, and mechanical loarings. The governing equations are based on the coupled generalized theory of piezothermoelectricity along with the modified Fourier law. The solutions are obtained by the method of characteristics. The numerical calculations are carried out for PZT-4 and nonpiezoelectric plates subjected to impulsive laser-pulse heating.

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The elastodynamic response of the transformation-toughened ceramics under an instantaneous phase transformation is investigated. Some composite materials, such as Zirconia toughened ceramics, are remarkable material, which has a high strength, a high elastic modulus, and an improved toughness, etc. Most of the good qualities are common in many ceramic composite materials. These good qualities are made possible through the phase transformation of composite particles. The transformation toughening utilizes the stress-induced phase transformation of particles, which is accompanied by a volumetric expansion. In this paper a phenomenological model is proposed to describe the situation, which involves a dynamic martensitic transformation in a spherical particle of Zirconia embedded in the infinite elastic matrix.

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The purpose of this research is to make the simulation model in order to design the roll press equipment for the wood board. In the first step of the research, we investigate the temperature analysis of the wood board under the roll press. The thermal conductivity is related with the temperature. The temperature distributions of the wood board are obtained for the few temperature conditions. The results are compared to the experimental data.

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This paper is concerned with the thermal buckling problem of an inhomogeneous rectangular plate due to partial heating. In such case, the problem becomes to be more complicated because the in-plane thermoelasticity problem should be solved to obtain the distribution of in-plane stresses. Thereafter, the thermal buckling analysis must be carried out. It is assumed that the material properties are changed in the thickness direction with the power law of the coordinate variable. The critical buckling temperatures are calculated using Galerkin method. Effects of the inhomogeneous material properties, aspect ratio and width-to-thickness ration on critical buckling temperature are examined.

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A method of solution is presented for torsion problems of an infinite elastic solid with a circular cylindrical or circular disk-like cavity. This is an example of application of a new fundamental solution shown in a previous paper for axisymmetric torsion problems of elasticity. A fundamental solution for torsion problems as usual is defined as a solution to the problem of an infinite elastic solid subjected to torsional body force acting along a circle. The new fundamental solution is defined as a solution for an infinite elastic solid subjected to torsional body forces acting uniformly on an annular plane and a cylindrical plane. Influences of the length of the cavity on stress distributions around the cavity are shown.

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In the present article, we deal with a one-dimensional spherically symmetric isothermal elastic problem of an inhomogeneous hollow sphere analytically. We assume that a hollow sphere has inhomogeneous material properties, in which the Young's modulus of elasticity is changed by the power product form with the radial coordinate variable γ. We formulate the Navier's equation for the inhomogeneous hollow sphere, thereafter we derive analytical solutions of displacement and stress components for the hollow sphere which is subject to uniform pressure from boundary surfaces. We carry out numerical calculations and discuss the effect of the inhomogeneity property of the Young's modulus of elasticity upon the isothermal elastic behaviors of the hollow sphere.

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This paper describes a numerical prediction method for thrombus formation in orifice-pipe blood flows. In this study, several types of orifice-pipe flows by using two turbulence models are computed, which k-εmodel with partly patched Launder-Kato model (LK-Zonal model) to improve computational accuracy. Using these database, quantity of thrombus is predicted by integrating (1) transport equation for concentration of blood coagulation factor and (2) shear velocity, and (3) wall distance. It is concluded that there should be large thrombus formation region in front of the orifice and in the recirculation area.

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