Linear stability of interfacial solitary waves is studied under the assumption that the fluid is incompressible and inviscid with no interfacial tension. Solitary wave solutions are obtained by numerically solving the corresponding governing equations. Their stability is investigated by solving the eigen-value problem for linear perturbations.

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In order to analyze the occurrence mechanism of the backflow at the inlet of inducer, a series of numerical calculations were carried out, Discussions are made based not only on the flow field at the inlet but also on the balance of the flow into/out from two control volumes. The analysis results show that the radial direction flow near the blade suction surface play a main role in the formation of backflow

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Turbopump inducers are designed with a certain atack angle even at the design point in order to improve suction performance. For this reason, the swirling backflow always occurs at the inlet of the inducer. As the flow rate is lower, it extends upstream and may cause various problems if it interacts with upstream elements. In this study, we investigated the backflow vortex structure at the inlet of the inducer by Large eddy simulation in order to elucidate the fundamental characteristics.

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It is known that fine particles can penetrate into the alveolus of the human lung and influence human health. However, it is not well understood how close to the human face aerosols can reach the nose. In order to elucidate the aerosol behavior in the vicinity of the human face with breathing condition (inhalation and exhalation), a two-dimensional turbulence model was employed to obtain the time-dependent airflows and particle transport. The capture rate of contaminants as a parameter of distance from the source and wind direction was determined. A two-dimensional standard k-ε turbulence model was used to obtain the time-dependent airflow distributions in the vicinity of human face with breathing was determined. Once the particles reach the nose, they are assumed to deposit in the human body. The time-dependent aerosols captured by the nose were evaluated as a parameter of distance from the source when the ambient air is still and in the presence of various wind directions.

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Flows of liquid crystalline polymers through 3-D slit flow cells with an abrupt expansion are simulated using the modified Doi model. The flow is calculated with the marker-and-cell (MAC) method. The twisted structure of orientation is observed at the downstream of the abrupt expansion and is maintained far downstream. The molecular orientation with the twisted structure is significantly affected by the expansion ratio and the cell gap. The distribution of molecular orientation induces the flow modification : The off-centerline velocity.

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The industrial electrostatic precipitatiors (ESPs) employ negative corona or point corona, which generates discrete discharge along the wire electrodes. Three-dimensional analysis of electrical characteristics and electrohydrodynamics is essential to describe the ESPs having tuft/point coronas. The distribution of the secondary flow (electric wind) is to form a donuts-shape ring from each tuft/point, extending further to inflow and outflow direction. When the primary flow exits, the flow interaction takes place, depending upon EHD number which is defined as the ratio of EHD Reynolds number to the ordinary Reynolds number or simply, the ratio of characteristic electric wind velocity to the primary flow velocity. The electrohydrodyanamic flow field is to form a pair of spiral vortex rings, like Goertler vortices in the direction of the gas flow. The effects of electrohydrodyamics on particle motion and ESP theory were discussed.

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In this paper, we propose a propulsion device by Knudsen pump which applies thermal creep flow. The thermal creep flow is characteristic flow of rarefied gas, and it is induced when boundary walls have temperature gradient. We performed experiments and ascertained the thermal creep flow, and the pressure rise. We consider that we can apply the high temperature of the sunlight part while the satellite is flying, and that we utilize it to propulsion device. We also examine the availability of Knudsen pump by simulation of DSMC method.

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It is well known that a backflow occurs in the upstream of an impeller at low flow rate. Such backflow often accompanies a vortex structure. The flow field corresponding to the upstream of turbo machine is investigated by using a simplified model. In this paper, the flow field is simulated by using the LES to investigate detailed flow pattern. The computed results are compared with experimental results.

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A steam control valve is very important to control the flow rate through the steam turbine in thermal plants. It is well known that flow induced vibration occurs at certain valve opening and pressure ratios. In the present report, 2-D CFD is used to study the effect of the radius ratio of the valve head to the valve seat on the flow induced vibration. An asymmetric oscillation causes the unsteady side load on the valve head. It was found the range of unsteady side load is smaller when the valve seat radius is larger than the valve head radius.

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This paper reports about experimental and analytical investigations of the effects of leakage clearance geometries on rotordynamic fluid forces in an centrifugal impeller executing axial vibration. It was found that, (l) When the clearance is smaller, the pressure on the front shroud become smaller, suggesting quasisteady instability.(2) The change of leakage clearance geometry affects the phase of the fluid force, through the variation of the leakage flow due to the vibrating motion.

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It is widely known that one of the reasons of pollution of lakes, marshes, and dams is due to the oxygen shortage in deep part of them. It is very important to improve the quality of water. In this study, we research the relation between bubbles generated by Micro Bubble Generator and increase in dissolved oxygen concentration. It seems that surface area of bubbles affects the increase in dissolved oxygen concentration.

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There is a technique using the centrifugal force to remove bubbles from liquid. Many researches have been carried out, which are, however, studies for simple cylindrical or conical separator or studies through numerical simulation. In this study, we made experiments using not only simple cylindrical separator but a cylindrical separator with conical core based on the structure of a vortex tube. It was found that the structure of the vortex tube is applicable to remove bubbles from liquid with small pressure different.

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The principle of continuous ink jet printer is to run ink droplets into printing paper. It is difficult, however, to form stable ink droplets, and moreover, unstable ink droplets cause disorder of printing performance. The parameters such as shape of nozzle, surface tension and pressure influence the shape of ink droplets. The purposes of this research are both to analyze ink droplet formation and to solve control factor of split process from ink column to ink droplet by using Computational Fluid Dynamics (CFD).

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Recently mixing technology is important to chemical engineering, food engineering, bio engineering and etc.. However, mechanism of emulsifying has not been fully understood. In this study, breakup process of oil droplets was visualized to clarify the emulsifying mechanism using an emulsifying equipment with homogenizing mixer. And diameter of the droplets was measured by PDPA (Phase Doppler Particle Analyzer). As a result, it was seen that the diameters of broken up oil droplets more strongly depended on rotational frequency of homogenizing mixer rather than kinetic viscosity of oil. And the presence of the baffle plates did not affect vertical convection of liquid around the plates, when viscosity of the liquid was very high.

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