Horizontal propagation of waves of inertial internal gravity modes in a rotating linearly stratified Boussinesq fluid is studied based upon the linear theory. We employed problems of both a line sink and a point sink flow in a reservoir of finite depth so that the twodimensional and the axisymmetric propagation of modes are investigated. Our consideration is mainly focused on time, space and rotating angular velocity dependence of their propagation speed, horizontal wavenumber and amplitude.

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In this paper, we describe swirl effects on pressure loss of a straight pipe flow, longer than 100 pipe diameters, for wide range of swirl strength. Pressure loss of a pipe flow depends on velocity gradient near the pipe wall. Turbulent swirling flow in a straight pipe is extremely different from no-swirl pipe flow. Tangential velocity distribution forms a combined vortex except a forced vortex swirling flow in whole region of the pipe. And in increasing swirl strength, axial mean velocity decreases in the central region and increases near the pipe wall. As a result, its resultant velocity near the pipe wall is several times higher than no-swirl pipe flow's, so that its pressure loss increases. In addition, boundary layer thickness is kept thin far downstream and turbulence near the pipe wall is almost equal to no-swirl turbulent pipe flow's. In decaying swirl strength, flow near the pipe wall is relaminarized and it is expected that pressure loss of such a flow is lowered in comparison with no-swirl pipe flow's in this region. Swirling angle at r/R =0.95, Θ_sw, is employed for swirl strength definition. Wall pressure measurements are performed in the wide range of swirl strength up to about Θ_sw, =73°.

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CIP (Cubic Interpolated Pseudo-particle) method is a numerical solver for the advection equations and is proven to be highly accurate and robust. The purpose of the present study is to develop a MHD (magneto-hydrodynamics ) code by using this method and to numerically analyze a plasma flow in a magnetic feild. At first, in order to trace the plasma surface effectively, the moving mesh method is adopted on this code. Analysis of plasma behavior in the magnetic cavity of a fusion reactor is performed. Then the interaction between a rotating plasma and a background gas in a magneteic field is investigated by using the code, and the formation of the spiral-vortex structure due to the tangential velocity shear is demonstrated for the first time. These results from the code show plasma behaviors consistent with the experimental result or other computation results.

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