The effects of external grid turbulence in a free stream on the turbulent boundary layer are investigated by means of the direct numerical simulation (DNS). A square turbulence-generating-grid, on which the velocity and components are set to zero, is located at a short distance downstream of the front edge of the flat boundary with a nonslip condition. The fractional step method is used to solve the governing equations. The results show that turbulence intensities, Reynolds stress, and heat flux normalized by the inner parameters are suppressed in the log-law region by the external grid turbulence.

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This paper describes the numerical study of a non-stratified airflow over real complex terrain. Attention is focused on a mechanism of a local strong wind induced by a topographic effect. To reproduce the above-mentioned local strong wind, it was shown that the horizontal grid resolution from 50 to about 100m was necessary.

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We have tried to simulate various types of atmospheric turbulent flow with the multi-fan type wind tunnel in Miyazaki university in order to investigate wind effects on structures. This wind tunnel can easily generate low frequency fluctuation and form arbitrary mean velocity profiles through computer-controlling each fan.In this paper, we will introduce the flow-generating techniques of atmospheric boundary layers and a gust, and then show basic characteristics of the simulated flows.

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Effects of overlapped electric double layer and interfacial charge on the ionic transport in 30 nm rectangular nanochannel are numerically investigated in this study. The numerical code which can calculates the electric field and ionic distribution in nanochannel is developed based on the Poisson-Nernst-Planck equation using finite difference method. The validity of the numerical code is confirmed from the view point of electro kinetic potential and electric neutrality. At lower ionic concentrations, the numerical result deviates from the Graham equation due to the overlapped electric double layer. The ionic distribution, electric field and ionic current are analyzed at various KCl concentrations. The ionic distribution in nanochannel is strongly affected by the interfacial charge especially at lower ionic concentrations and K^+ ions increased in nanochannel due to the electric neutrality. As the result, the ionic current increases at the lower KCl concentrations from 0.10 to 0.40 mol/m^3.

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We employ the molecular dynamics method to simulate osmotic equilibrium of ideal solution and pure solvent separated by a semi-permeable membrane in a micro vessel. The validity of van't Hoff law in the system is examined for several values of concentration of solute in the solution. After introducing the motion equations for assemblies of solvent and solute molecules, we discuss stress terms in the equations.

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Style of ski jumping has been changed from a parallel one to a present V-style. Lift-drag ratio changes with the style of jumping. Flow field also changes with it. The difference of flow field was observed with smoke wind tunnel, cotton ball and tuft method. While strong but narrow band down wash was appeared in a wake of the parallel style, Wide band down but weaker wash was seen in that of V-style.

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