Numerical simulations using the time dependent quantum dynamics are carried out on the electron wave packet behaviors through a GaAs quantum interference transistor (QUIT). In order to trace the respective electron wave packets passing through the two hyper fine channels of QUIT, an attempt to introduce their relative phase difference results well in solving the equation system of time dependent quantum dynamics in terms of one dimensional finite difference scheme. The performance as QUIT strongly depends on the interference characteristics of two wave packets, and the interference is well controlled with the aid of externally impressed external electric and/or magnetic fields. The simulation results show the possibility that GaAs QUITs are potential devices which operate as 0-1 controller with ultra high speed and accuracy due to the optimum electric and/or magnetic fields. The present QD simulation may contribute to practical designing and fabricating of QUIT devices.

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The growth process of metal-containing fullerene was studied by using the molecular dynamics method. Based on DFT (density functional theory) calculations of various forms of small clusters MC_n (M=La, Ni), multi-body potential functions between carbon and metal atoms were constructed with the Morse-type term and the Coulomb term as functions of coordinate number of a metal atom. The clustering process starting from 500 isolated carbon atoms and 5 metal atoms in a 342Å cubic cell was simulated under the controlled temperature condition at T_c=3000 K, and the growth history of metal-attached clusters was studied in detail. Fan-type structure was reproduced around the metal atom for MC (n<5), and mono-cyclic ring or bi-cyclic ring was observed for both La and Ni system. An open cap structure was formed around a lanthanum atom for LaC_n (20<n<50) due to the strong Coulomb interaction, while tangled-poly-cyclic structures and random cage were dominant for NiC_n (20<n<50). The lanthanum atom was completely enclosed in the carbon cage at the final stage, though the nickel atom attached on one face of the caged structure.

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The experiment of a gas molecule scattering from a clean graphite surface is performed using the molecular beam technique. The molecular beam experiment is performed in the ultra high vacuum molecular beam scattering system. The supersonic molecular beam is produced in a three stage differentially pumped vacuum system by expansion of gas through a nozzle. In the second stage of the beam line, a rotating disc chopper is mounted to do time of-flight measurements. The base pressure in the main chamber where the graphite is placed is 3.7×10^-7Pa (2.8×10^-9 Torr). The graphite sample is mounted on a six-axis manipulator. The scattered molecule is detected by a rotatable quadrupole mass filter detector. By using the manipulator and the detector, the in-plane and out-of-plane scattering of a gas molecule can be measured.

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Three dimensional interacting flowfield of two parallel axisymmetric jets is calculated by the DSMC method. Under limited computer resource it is not easy to simulate the three dimensional flowfield using the method, because every volume of cell is very small and the number of molecules within the cell becomes also very small. In the present calculation the upstream flowfield of each orifice is assumed to be axisymmetric and only the downstream of the orifice is managed to be three dimensional although the downstream flowfield is restricted within one fourth of the full flowfield. The secondary jet-cell that is formed with two barrel shocks of the two primary jets can be seen clearly in the middle between the jets. The fundamental flow structure calculated by the DSMC method is compared with the experimental result of flow visualization by the laser induced fluorescence technique.

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A Pulsed Flame Jet (PFJ), formerly referred to as Pulsed Combustion Jet, has a great potential to enhance ignition and burning rate in lean fuel-air mixtures. In order to investigate the ignition mechanism of PFJ, radicals in the jets were measured. CH emission in the jet issuing into the combustion chamber, where the lean mixture was filled, was measured using a band pass filter and a time gated intensified CCD camera. OH radical in the jet issuing into the air was measured by PLIF (Planar Laser-Induced Fluorescence). In the tests, methane air mixtures were used, and PLIF images were obtained in the plane perpendicular to the jet axis as well as in the plane of the jet axis. Then the variation of CH emission and OH fluorescence area and their intensity in the jet were revealed.

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An experimental study on microscopic scale measurements of thermal expansion and temperature by using the Scanning Joule Expansion Microscope (SJEM) based on the Atomic Force Microscope (AFM) was conducted. While the AFM is scanning on the sample heated by AC current, topographical and thermal expansion images are measured simultaneously by detecting DC and AC motions of the cantilever. In order to apply this technique to the temperature measurement in microscopicscale, the sample was covered with a thin film of polymer (PMMA) which has a high thermal expansion coefficient compared with metals and dielectric materials. Merits of this technique are (1) quite simplicity of measurement because of using the commercial cantilever instead of complicated thermal cantilever for the typical Scanning Thermal Microscopy (SThM) and (2) a higher spatial resolution of 20 nm which is restricted by the point contact scale between the cantilever and the sample.

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In order to clarify the growth of ice crystals containing adsorbed silane coupling agents (SCAs), a fundamental and microscale analysis has been conducted. By using an optical microscope, the growth patterns of the ice crystals were experimentally investigated while neglecting the influence of heat flux. It was found that some SCAs that particularly have three hydrophilic groups in a molecule can be adsorbed by the ice crystal surface preventing further growth of the crystals towards a-axis direction. We also investigated the surface of the ice crystals by using a scanning tunneling microscope (STM) in order to determine the influence of SCA on the microscale surface structure. Systematic grooves aligned about 75° to the hexagonal side on one bipyramidal plane were observed. Those grooves were at least 500 nm long, 30∼70nm deep, and existed at about 200 nm intervals.

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In this paper, molecular simulations using a genetic algorithm are conducted to investigate the stability of deposited atoms on a substrate. First, to confirm the validity of the method, the stability of structures of L-J clusters is studied and it is successfully shown that a stable 13-atoms cluster has a well-known icosahedral structure. Then using this method, the stability of structures of deposited atoms on a solid surface is investigated. The results show that deposited atoms have either an island or a layer structure, depending on the combination of intermolecular potentials of the deposited atom and the substrate atom. Furthermore, to apply the method for systems having a certain temperature, a new method using a modified intermolecular potential is proposed. The results of the advanced simulation agree qualitatively with those of the MD simulation. Although the GA simulation gives good results, it also requires much less CPU time than MD simulation. Therefore, it can be concluded that the GA simulation is a superior technique for examining stable structures of many-particle systems.

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The effects of contamination on gas dissolution process of a spherical rising gas bubble in water was investigated experimentally and numerically. We developed an experimental system that use a CCD camera coupled with a microscope to track the rising bubble. By measuring the bubble size and the rising speed from the bubble motion data captured by a personal computer, we could precisely estimate the drag coefficients and the Sherwood number for the dissolution of gas bubbles in the transient regime where the bubble changes from behaving as a fluid sphere to behaving as a solid particle. We also numerically estimated drag coefficients and Sherwood number of "the Stagnant Cap Model" by directly solving the Navier-Stokes equation and the convection diffusion equation. The experimental and numerical results are in good agreement and clarified the mechanism of the transient process where the bubble behavior changes from that of a fluid sphere to that of a solid particle.

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Two-dimensional characteristics of boiling two-phase flow of liquid helium in a duct flow are numerically investigated to realize the further development and high performance of new cryogenic enginering applications. First, the governing equations of boiling two-phase flow of liquid helium based on the unsteady drift flux model are presented and several flow characteristics are numerically calculated taking into account the effect of superfluidity term. Based on the numerical results, the two-dimensional structure of boiling two-phase flow of liquid helium is shown in detail, and it is found that the vapor gas phase strongly spreads throughout to the inner flow duct because of the change of pressure gradient due to the effect of superfluidity which appears in the momentum equations. Next, it is clarified that the distribution of the void fraction, velocity field and instantaneous streamline of two-phase superfluid helium flow show quite a different tendency from that of normalfiuid helium because the counter flow of two-phase superfluid occurs against to the normalfiuid flow. According to these theoretical results, it seems reasonable to predict the fundamental characteristics of cryogenic boiling two-phase flow. The numerical results obtained should contribute to advanced cryogenic industrial applications.

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The effect of spatial resolution of LES on the trajectories of particles was studied. Particle trajectories calculated in high resolution LES were compared with those calculated in flow fields filtered by sharp cutoff filters. The relation between Stokes number St and λ the minimum length scale of eddy which affects the particle motion was investigated by analysing results of the present numerical calculation as well as by a theoretical approach. It was found that, in the present range of St, the theoretical correlation describes well the tendency of the present numerical prediction.

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This paper deals with two one-dimensional models for a collapsible tube based on the three-dimensional calculation of the tube deformation with the finite element method. The complex deformation of the tube due to an external pressure was calculated for the condition of no flow though the tube. The numerical results for the tube deformation agree with the experimental measurement. In the present one-dimensional models the collapsible tube is modeled as a simple membrane or a beam. Comparing the three-dimensional computational result with those of the one-dimensional membrane model and the beam model, the equivalent tension and the equivalent beam thickness were derived. By comparing the numerical and the experimental results, the validity of one-dimensional models was investigated for both the steady flow and the unsteady flow with a self-excited oscillation. It was shown that both of one-dimensional models qualitatively represent the characteristics of the collapsible tube.

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Finite difference method in a collocated grid system has the merits of both regular and staggered grid systems, and has mainly been used for steady flow simulations. Recently, some unsteady flows have been simulated by using the collocated grid system. The author pointed out a violation of kinetic energy conservation in the collocated grid system, which is important to unsteady turbulent flow simulations. In this paper, a modified algorithm for improving the conservation property of the collcated grid system is proposed. Van Kan type pressure correction is introduced to minimize the defect. The modified algorithm with fourth order accuracy in space is also proposed. Conservation properties of the numerical algorithms in the collocated grid system are demonstrated on the example of two dimensional periodic inviscid flow simulations. Plane turbulent channel flow simulations are also performed to confirm the reliavility of the modified algorithm.

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Linear unsteady aerodynamic calculation of vibrating cascade blades has a great importance due to the small usage of the computer resources and its utility in practical flutter analysis compared with the non-linear and time accurate calculations. The application of the Lax-Wendroff method, which has been conventionally used in the linear unsteady calculation of vibrating cascade blades, may pose difficulty in applying the appropriate artifcial viscosity. In the present paper, the TVD scheme combined with the finite difference method has been proposed, so that the linearized unsteady flowfield of vibrating cascade blades free from the spatial numerical oscillation should be obtained as will be demonstrated in the accompanying second paper.

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For Taylor vortex flows developing between two concentric cylinders with finite length, the Reynolds number based on the rotation speed of the inner cylinder and the aspect ratio defined by the cylinder length and the gap between cylinders are dominant parameters which determine modes of flow patterns. In this study, the flow modes in decelerating flow are examined numerically. The finite difference method is used to solve unsteady axisymmetric Navier-Stokes equations. At a constant aspect ratio, the flow has three modes: primary mode, normal secondary mode and anomalous mode. The qualitative process of flow pattern exchange from the secondary mode to the primary mode is revealed and the Reynolds numbers at which flow modes change are determined. In the flow with anomalous cells, extra vortices near the end wall of cylinder merge and make the flow mode normal. The result shows good agreement with experimental observations.

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Outflow boundary conditions for direct numerical simulation of compressible flow are proposed. In the newly developed boundary conditions, flow field near the outflow boundary is decomposed into compressible and incompressible parts by Hehnholtz decomposition. Navier Stokes Characteristic Boundary Conditions (NSCBC) are used for compressible part. Convective-viscous boundary conditions with transport equation for pressure (CVBCTP) which produce very accurate results in incompressible flows are applied for incompressible part. Both boundary conditions are superposed to define final one. The new boundary conditions are applied to three test cases which are acoustic wave propagation, a single vortex passing through boundary and a single vortex with acoustic wave propagation. The results show that the present boundary conditions provide a significant improvement over the conventional boundary conditions.

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Numerical simulation of the oscillation of a pseudo-shock in a straight channel was made, using the explicit, second-order accurate Harten-Yee's upwind TVD scheme and the Reynolds averaged Navier Stokes equations. The basic frequency of the shock wave is the same as that of the back pressure fluctuation. The oscillation of the shock wave is similar to the forced oscillation of the simple one freedom vibration system with damping. At low Mach number, the damping effect is high, while at high Mach number it is low, and the strong resonance occurs.

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When gas is suddenly injected from a nozzle into a stationary liquid in a horizontal circular pipe, a thin liquid film is left on the wall after the passage of the interface flout. The residual liquid film thickness in the case of the progress of the interface front at constant velocity is studied. The liquid film thickness quickly decreases and approaches an asymptotic value immediately after the front passes measured point and it decreases slowly after that. For low or high front velocity, the asymptotic value is almost constant regardless of the front velocity. For middle front velocity, it increases with the front velocity and depends on the capillary number. The asymptotic thickness agrees well with modified Bretherton's equation derived by replacing the inner diameter of the pipe by a virtual diameter. The limit front velocity, to which the modified Bretherton's equation is applicable, depends on the Reynolds number, which the virtual diameter or the thickness of gas bubble is used as the characteristic length.

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A thin liquid film is left on wall after passage of a gas liquid interface front in a horizontal circular pipe filled up with water. The effect of the surface roughness of the inner surface of the pipe on the residual liquid film thickness is studied analytically and experimentally. Taking account of the increase of the pressure drop owing to the surface roughness of a wavy wall, the residual liquid film thickness on a wavy wall is analyzed by the same method as the thickness of film remaining on a surface of a solid withdrawn from a quiescent liquid. The numerical analysis of the pressure drop in a wavy wall channel is performed by an integral momentum method. The present study suggests that the surface roughness (2e) of the pipe effects on the residual liquid film thickness δ if δ<2_ε.

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In the present study, the time variation of flow through the side branch of the right angle branch has been experimentally studied in the laminar steady flow by laser Doppler velocimeter. The side branch 14 mm in diameter bifurcates at right angle from the trunk 24.5 mm in diameter, and the shape of both upstream and downstream corners at the entrance of the side branch is square edge. The flow in the side branch periodically oscillates, and this oscillating flow is a characteristic phenomenon in the right angle branch. The Strouhal number based on the variables in the side branch is proportional to the Reynolds number. It is implied that the oscillating flow might be induced at the boundary between a small vortex formed in the reversing zone in the side branch and a large vortex in the core flow in the side branch. The rotating direction of the small vortex is the same as that of the large vortex.

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Turbulent boundary layers subjected to a sudden change ill boundary condition from a smooth flat plate to a "rod wall" with two dimensional openings have been studied experimentally. The rod wall consists of circular wires, which are equally spaced in the streamwise direction and whose diameter is the same as the thickness of the upstream plate. Three different spacings of wires are tested; the spacings are two to four times of wire diameter. Comparative measurements are made on rough walls which are geometrically the same as the rod walls but have no openings. With decreasing the wire spacing, the internal layer formed downstream of the change in wall condition develops faster and the turbulence intensity of longitudinal velocity component becomes larger. Pronounced maximum occurs in the transverse distribution of the flatness factor of velocity fluctuation, which yields a measure of the internal-layer thickness.

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Two turbulent spots were generated in a zero pressure gradient laminar boundary layer by issuing small air jets with a time interval T_d from two horizontally displaced holes on a flat plate and interaction phenomena between them were experimentally investigated. When the two spots were simultaneously generated (T_d=0), they merged into a larger single spot of which the normal growth was apparently enhanced and the velocity defect was intensified from the original spots in their merged region. The upstream spot generated with a time delay Td intruded into the calmed region of the downstream foregoing spot as it grew downstream. Then, its height was reduced and turbulence intensity was decreased, whereas it kept almost the same spanwise growth rate as that of the single spot. The normal growth of the downstream spot was scarcely affected by the intrusion of the upstream spot.

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A turbulence model is proposed for the three-dimensional vortex blob method. This model employs a modified version of the core spreading method introduced by Leonard and Chua (1989) in the spirit of Smagorinsky type of eddy viscosity. The diffusion of vorticity by the molecular viscosity is represented by the core spreading whose rate is approximated by that of the rectilinear viscous vortex tube. The linear combination of the two viscosities yields a Lagrangean turbulence model which includes effects of Reynolds number. Each model is applied to an impulsively started round jet forced by two helical disturbances rotating in the counter directions. Vortical structures in the jet are compared among the models to show that the combined model can be a reasonable turbulence model.

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The flow around a rotating circular cylinder placed at various heights above a moving plate that is used to remove the boundary layer on the plate has been investigated experimentally and numerically for the high Reynolds number (Re=7×10⁴). The minimum clearance where the vortex shedding from the rotating cylinder is disappeared was found and it was not affected by peripheral velocity. Furthermore, the switching phenomenon of the flow around the rotating cylinder that had been observed in 2nd report was disappeared by removing the turbulent boundary layer on the plate. The calculated results for lift and drag coefficients, Strouhal number were compared with experiments. It was found from the calculated results as well as the experimented one that the presence of the plate had strong effects on the flow around the rotating cylinder.

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An impulsive pressure wave which is called a "micro-pressure wave" radiating from a tunnel exit is one of the important environmental problems in high speed railways. The magnitude of the impulsive wave depends on the waveform of compression wave at the tunnel exit; the steeper the wavefront of the compression wave, the larger the impulsive wave. In our previous study, the distortion of compression wave during its propagation through a slab track tunnel was investigated by one dimensional numerical analysis which took account of steady and unsteady wall friction and of heat transfer to the tunnel wall. As a result, it is shown that verification of effects of short side branches arranged at side walls of tunnel is needed to predict the distorsion of waveform. In this study, the effects of short side branches are analyzed by acoustic analysis and included in numerical analysis. The results show that the numerically obtained waveforms agree well with field measurements which are obtained from a slab track tunnel of Shinkansen.

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The lateral force on the railway cars due to the side wind sometimes causes the suspension of the service and at worst serious accidents. The reduction of the force is important for the railway service. We present here a technique of passive control of boundary layer, in which thin fins are set on the upper side of the car, and show by experiments and numerical simulations that the technique is effective for reducing the lateral force. The force is reduced up to 25%.

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The flow pattern through an impeller with finite thick blades is generally different from that of infinitely thin blades due to the influence of blade thickness. The present work set out to investigate this phenomenon. The velocity measuring method based on the use of Laser-Doppler velocimeter (LDV) was applied in this paper for determining parameters of flow through twin blades of diagonal impeller of fish transporting pump. Three components of absolute velocity were measured on three surfaces of revolution inside and outside of an impeller near exit. The relative velocity components were also calculated from these flow measurements. A method of analyzing subsonic inviscid flow on a stream surface of revolution of a turbomachine, was used. The singularity method of calculating a two dimensional incompressible and inviscid flow has been applied to obtain a distribution of relative velocity in the region between two adjacent blades and outside of the impeller. A Kutta condition for the flow in the region of a rounded trailing edge was successfully used. The comparison of the calculated results with the experimental data shows good agreements.

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An accurate numerical analysis of the flows associated with impeller-volute configurations in turbomachinery can be extremely helpful in optimizing the performance of centrifugal turbomachinery. In the present study, without introducing the periodicity of the blade-to-blade stream, the two dimensional unsteady features of the flows through a centrifugal impeller rotating in a volute casing of a pump are directly simulated by using an advanced vortex method. Results are presented in the form of the flow pattern of discrete vortices, volocity vector, theoretical head coefficient of impeller and the unsteady hydraulic radial force on impeller. Some of the results are compared with experimental data and the agreement is found to be good.

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The flow in a flush type inlet duct of water jet propulsor is investigated both experimentally and numerically. In the experiment, a duct model is tested in a low speed wind tunnel facility. Stagnation pressure distribution at the exit of the inlet duct (i.e. pump inlet) is measured in detail. The measured data shows that the location of high loss region moves from ramp side to lip side as IVR (Inlet Velocity Ratio) increases. Meanwhile, 3-D Navier-Stokes code is apllied to this duct flow. The computed results reveal the complicated flow mechanisms inside and around the inlet duct, which is highly three-dimensional and strongly affected by viscouscity.

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As the first step of the study of cavitation in the tip leakage flow of turbomachinery, experimental and numerical studies were carried out to investigate the characteristics of cavitation in the 2-D unsteady tip leakage flow. The numerical method was constructed by combining the vortex method with taking into account the effects of cavity growth. Three types of cavity models are examined. It is shown that one of them simulates the location and the size of the cavity fairly well. Comparisons with experiments are made for three values of initial pressure and for three values of tip clearance. The model can predict those effects and it is expected that the present model is useful for the estimation of cavitation characteristics of 3-D tip leakage flow.

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When a manipulator is operated in water, fluctuating fluid forces produced by vortex formation will cause problems in precised positioning control of the manipulator. However, in this kind of studies to date, people were mainly interested in control theory of linearizing the nonlinear drag evaluated from assumption of constant drag coefficient, and nobody paied attention to the fluctuating fluid forces due to vortex formation. On the other hand, the presence of strong irregularity in vortex shedding from a two dimensional bluff body ill uniform flow is reported by number of researchers. Therefore, nonrepeatability of fluctuating fluid forces acting on a manipulator arm repeatedly commencing its motion in still water is expected to appear. In this study, two kinds of circular cross sectioned manipulator arms were provided. Then, one was towed and the other was swang in still water. In eatch case of motion, variation of fluctuating lift with towed distance or swing angle was measured for one hundred times. From ensembly collected data at particular towed distance or swing angle, presence of nonrepeatability of fluctuating lift was clarified.

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An interferometric CT (computed tomography) technique is developed to investigate three dimensional phenomena of shock waves in shock tube experiments. Interferograms of shock waves discharged from a pair of circular open ends are taken in the multi directions, and analyzed by the computer aided fringe pattern analysis and CT reconstruction technique. The resultant density distributions show that the present system of the interferometric CT technique is effective for the unsteady shock wave phenomena.

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A numerical flow analysis method combined with a heat conduction analysis of the shock tube wall was presented in the first report. Results of thermal protection testing which were carried out at the condition of 25 MJ/kg stagnation enthalpy using a high enthalpy shock tunnel and its surface temperature analysis are presented in this paper. Two kinds of materials, nickel and cobalt-based super alloy, were selected as materials of thermal protection. Though the protection made of cobalt-based super alloy which had been selected because of its strength and toughness at high temperature was severely damaged after only one shot, the protection made of nickel withstood a total of 9 shots. The calculation results of the surface temperature analysis showed good agreement with the results of observations after the shots. The friction factor model which considered the high temperature generated by the passage of a reflect shock wave gave good results for the surface temperature.

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A numerical flow analysis method combined with a heat conduction analysis of the shock tube wall was presented in the first report. Results from thermal protection testing which was carried out at a 25 MJ/kg stagnation enthalpy using the high enthalpy shock tunnel T5 of the California Institute of Technology and results from the surface temperature analysis were presented in second report. Though the present analysis method will be able to predict flow conditions and temperature rises of the wall for an individual tunnel operation condition, it is necessary to know the limitation of thermal protection for the whole range of tunnel operation conditions. An equation, which shows the relationship between flow condition in the downstream region of the shock tube and the surface temperature of the tube, is deduced from the analytical solution of the unsteady heat conduction equation. This equation is simplified by using an approximation of the thermodynamic state which influences heat transfer of the stagnation region directly. The limitation curves calculated by this simple equation show good qualitative agreement with the experimental results. This simple equation also shows effects of apparatus scale and material on the limitation of thermal protection.

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The instability of a back flow layer on a diffuser wall and that of a main flow with vorticity have already been pointed out theoretically as the cause of rotating stall in a vaneless diffuser. Each instability of the back flow and the main flow, however, has not yet been proven experimentally. This study was carried out to examine the cause of rotating stall in a vaneless diffuser. The air jet from a small nozzle was used to control rotating stall in the diffuser. Rotating stall was completely suppressed by the jet in the opposite direction to the impeller peripheral velocity vector, and amplified by the jet in the same direction to the peripheral velocity vector. The cause of rotating stall and the mechanism for the suppression/amplification are discussed based on the experimental result.

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A calibration facility based on gravimetric method has been developed at NRLM for small mass flow rates of gas. This calibration facility establishes a primary gas flow rate measurement standard in Japan with an extended standard uncertainty of 0.12 percent at maximum, in mass flow rates from 0.01 g/min to 50 g/min for nitrogen. Five sonic Venturi nozzles were tested using this facility and the results showed that they can work well as a flow transfer standard for small mass flow rates. These sonic Venturi nozzles can be used to establish flow transfer standards within an extended standard uncertainty of 0.15 percent.

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Jet interference causes serious deterioration of efficiency in multi nozzle Pelton turbines especially in the operating region of low energy coefficients and high discharge coefficients. Since the jet interference is intensified by the scale effect, it is difficult to predict the jet interference of a prototype only from its low-head model test results without consideration of the scale effect. Therefore, theoretical approaches for predicting prototype jet interference are urgently required. In the present study, the scale effect of specific energy on jet interference is investigated using the relative jet paths with the velocity deceleration model of a free jet, in which scale effects in the free jet due to the internal friction, the entrainment of water droplets into the jet and the domino effect based on the discharge from the cutout of the buckets are considered. The predicted intensity of the discharge from the cutout shows a good correlation with the deterioration of efficiency due to the jet interference.

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It is well known that the fluid dynamics of arterial blood flow plays an important role in arterial diseases. The periodic blood flow, which has intermittent time, through a stenosed tube with a moving wall is analyzed numerically. The Windkessel model is used to express arterial wall movement and a revised Casson model is used for a constitutive equation of blood. The flow is assumed to be periodic, incompressible and axisymmetric. The influence of intermittency on flow through a stenosed tube is investigated. Stream lines, flow patterns and distributions of shear stress at the wall are obtained. The results show that the strength of the vortex is dominated by the reduced St number using angular velocity of unsteady time and that the effect of intermittency on flow is significant.

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This paper experimentally investigates a behavior of a bioconvective pattern under super gravitational fields. Experimental materials are the high density culture media of Tetrahymena. A centrifugal force was used to synthesize various super gravity conditions by using a spin tester that can generate 1-12[G]. To realize the decreasing effect of bioconvection pattern size by the increase of synthesized gravity, different lengths of a rotative beam are used to change the rate of Corioli's force and synthesized gravity. The main results are as follows: (1) The size of the convection pattern is reduced by an increase of the synthesized gravity. (2) Under synthesized gravitational field, the stream mode of bioconvection is changed by the Corioli's force. (3) The maximum transition velocity (upward, downward) of Tetrahymana is obtaind with the 2-4[G] condition. (4) The decrease in the size of convection pattern is due to the composite gravity.

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Numerical calculation has been carried out for the laminar heat transfer in a two dimensional channel bounded by a fixed wall and an oscillating wall. In this calculation, the moving boundary problem was transformed into the fixed boundary problem using the coordinate transformation method, and the fully implicit finite difference method was used to solve the mass, momentum and energy conservation equations. The calculated results are summarized as follows: (i) The wall oscillation has an effect of enhancing the heat transfer and an effect of increasing the additional pressure loss. (ii) The optimum Strouhal number for the enhancement of heat transfer exists, and this optimum value is strongly affected by the amplitude of wall oscillation.

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The effects of particle size on the particle behavior and heat transfer coefficient around a horizontal tube in a gas-solid fluidized bed were quantitatively investigated. Three kinds of glass beads with different average diameters (0.2, 0.42, and 1.0 mm) were used in this experiment. The local particle behavior and instantaneous heat transfer coefficient on the tube surface were simultaneously measured. Comparing the experimental results with the existed theoretical heat transfer model, the differences of the heat transfer mechanisms between the different particle sizes were made clear.

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An experimental test is conducted to attempt heat transfer augmentation in the channel flow, which shows drag reduction. As is known, addition of small amount of surfactant to water can reduce turbulent frictional drag considerably. Many investigations have been carried out to apply this profit to district heating systems, but confirmed that the heat transfer is reduced simultaneously. For the application of this phenomenon to a heat exchanger, with considering the disproportion between the momentum and the heat transfer, special technology for heat transfer augmentation is needed. Then, in this study turbulence promoters were introduced, and the possibility of heat transfer augmentation with the promoter in the drag reducing flow was investigated.

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We experimentally investigated the radiation heat transfer occurring in a gas solid fluidized bed between the fluidizing particles and a cooled heat transfer surface. To evaluate this heat transfer, radiation emitted from fluidizing particles to the cooled surface was measured using an infrared (IR) camera, which is located external to the bed so as not to disturb the bed fluidization. By doing this, the cooled surface was made of transparent CaF₂, and was cooled by air convection. Our results revealed that there exist cooled fluidizing particles adjacent to the surface and they suppress the radiation heat transfer between the surface and high temperature fluidizing particles in the depth of the bed. In addition, the effects of the fluidizing velocities, the radiative characteristics, and the particle diameter on the radiation transfer were clarified.

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Directional distribution of bidirectional reflectance ρ for visible laser irradiation is investigated experimentally on rough metal surfaces. The reflection is found to be far from perfect-diffuse. Relationship of reflection characteristics and runs surface roughness Σ is not simple in case Σ is of an order of the wavelength of incident radiation. It is recommended to analyze the reflection characteristics on (ρ cos θ_R), where θ_R is the zenithal angle of reflection. What has been called 'off specular' peak does not appear in this case. A reflection model for describing the directional distribution is presented for heat. transfer applications. The model can evaluate the values of the specular component Rs and the perfect diffuse component R_d of the hemispherical reflectance R_H for directional incidence. Calculated values of the specularly reflected energy ratio (R_s/R_H) do not always fit with our impression on the specularness in the directional distribution of ρ.

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A fast algorithm is developed to solve radiative heat transfer problems is non-gray gas system surrounded by gray walls. In the problem, the distribution of the gas temperature and the wall heat flux in non-gray gas are estimated. In the present study, the time consuming Monte Carlo method is used only outside the iterational loop of the temperature convergence. For the purpose, the R_d values, the ratio of the radiative energy absorbed by an element to the energy emitted from a source element, are separated into two parts, the absorption-coefficient-dependent part and independent part. The calculated values of R_d are used as the input data for direct exchange areas for the zone method to obtain total exchange areas. The new method reduces the computation time by one sixth compared to the conventional R_d method. Therefore, the fast R_d method combined with zone method is advantageous for the analysis is non gray gas systems. Comparison between the results of the present method and exact solution shows the validity of the present method.

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Two dimensional numerical calculation of heat generation and transport in GaAs MESFETs with high frequency gate bias has been performed. In order to study the conjugate nature of electronic and thermal phenomena in the semiconductor devices, electron particles, momentum and energy equations, and the energy equations of optical and acoustic phonons as well as Poisson equation are solved simultaneously. Calculated results exhibited the effect of temperature distributions to the current charactreistics as high frequency gate voltage variation.

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The dynamics of heat exchanger networks, parallel and series connections of two heat exchangers are investigated. Experiments of two steam-condensers cooled by water in tubes are performed and show intersting phenomena on both parallel- and series-heat exchanger networks. The characteristics of the parallel systems are mainly influenced by a stream splitting, i.e., the flow rate distribution and the transportation lag time in the pipe connecting each heat exchanger and a confluence point. The magnitude and phase of water (cold stream) outlet temperature change against a water flow rate change input show fluctuations in the lower frequency range. In the same manner, the magnitude and phase of the series systems also show a fluctuation in a lower frequency range. These behaviors are caused by the effect of the size ratio of the primary heat exchanger to the secondary one and the lag-time in the pipe connecting each heat exchanger. Consequently, it is clarified that both the parallel and series systems are sensitive to the transportation lag-time in the pipe. The results shows the importance of a fluid transportation model in the pipe on the dynamics of the system.

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In this paper the time-dependent characteristics of the natural convection in a vertical slot with hot and cold side walls were experimentally examined. In the experiment test liquid was glycerine-water mixture (80 wt%) and the Prandtl number in the center of the slot was held constant of 295. The Grashof number was changed in the range between 370 and 3.06×10³. As a result, it was revealed that the low pass filtering for the time evolution data of temperature made it possible to compute the largest Lyapunov exponents precisely. The region of the secondary flow cells was divided into the chaotic region and the non-chaotic One. Moreover the secondary flow cells appeared in the region in which the power spectrum of temperature fluctuation was regarded as significant and the region in which the auto-correlation coefficient decreased rapidly with time.

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