Large Eddy Simulation of downward fully developed particle-laden turbulent channel flows were performed with considering inter-particle collisions and fluid sub-grid scale components at Reynolds number 180 and 644 respectively. The effects of Stokes numbers, turbulence sub-grid scale components and inter-particle collisions on the distributions of solid particles were discussed. It was verified that, regardless of the Reynolds number of fluid flows, the maximum departure from randomness is when the ratio of the particle's aerodynamic response time to the Kolmogorov time scale of flow was approximately one. In addition, the simulation results showed that the degrees of particle preferential concentration are selectively associated with the sub-grid scale components of fluid turbulence because preferred particles were affected by preferred scale of the eddy structure around.

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In order to evaluate of physical quantities transformed through Atmosphere-Ocean interface, we performed two-phase flow simulations by means of C-CUP (CIP-Combined Unified Procedure) method for deformable free-surface flow with high wind shear. According to analysis of turbulent statistics, it was suggested that vertical velocity fluctuation became large near air-liquid free-surface, and mechanism for transportation of turbulent energy at the gas-phase into the liquid-phase by Reynolds stress produced by the fluctuating free-surface corresponded well with results of wind-wave tank experiments. Moreover, it was suggested that the evaluated values for both frictional stress and root-mean-square of free-surface fluctuation under corresponding mean wind velocity were in good agreement with results from previous experiments. Therefore, in this study, it was shown that numerical simulation with C-CUP method might represent realistic momentum transportation processes in air-liquid systems.

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Modern day helicopters are frequently required to operate in various flight situations. It is a case in point that a helicopter hovers closely and partially above a heliport which is on top of a high-rise building and the helicopter rotor is subject to Partial Ground Effect. In such flight situations, it is important to grasp effects of the complex ground geometry on rotor aerodynamic performance quantitatively. In this paper, the horizontal distance from rotor hub center to ground edge and the rotor height are adopted as parameters of Partial Ground Effect and based on the vortex method, we predict numerically the effect of such parameters on collective pitch angle, induced torque and coning angle of a hovering rotor in Partial Ground Effect. After discussing validity of the numerical method by comparing numerical results with experimental data, it is also clarified by showing flowfields around the rotor that due to the rotor wake contraction, there is a specific horizontal distance range where the rotor performance are not consistent with the geometric flight environment between rotor plane and boundary plane.

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