Numerical Simulation On Atmospheric Boundary Layer And Downburst Wind Field

With the increasing and deepening research on wind-resistance structure, how to accurately simulate the atmospheric boundary layer which accord with the real character of wind field becomes an essential problem. In order to study the numerical simulation method of the atmospheric boundary layer fluctuating wind field, by means of CFD software, the ideal random fluctuating wind is generaes with arranging the structural measures such as the roughness element, the spoiler lever and the grille in the full-size wind field model. The effect of numerical simulation results on some main parameters such as the height of roughness element, the spacing of spoiler lever and the arrangement of grille are analyzed. Moreover, numerical simulations to the four landscape wind field in Chinese Construction Code are conducted. In addition, downburst as a usual disaster, whose effect to the construction structure hasn’t given in the Chinese Construction Code, the static-type and moving-type downburst are simulated and attained a few conclusions1. Atmospheric boundary layer fluctuating wind fielda. Roughness element will significantly magnify the near ground turbulence intensity, with the increase of the size of roughness element, the magnifying effect and influence scope will also enlarge.b. The magnifying effect of spoiled lever to turbulence intensity of the top side of flow field is obvious, the effect of magnifying is enlarge with the increase of the density of spoiled lever.c. Through the arrangement of spanwise grille, the turbulence fluctuation which is in the interface part of effect scope of both roughness element and spoiled lever can be auxiliary increased.d. Through the arrangement of roughness element, spoiled lever and spanwise grille, the transformation of boundary layer wind field can be realized, the feasibility of generating boundary layer wind field pulsating entrance simulation method can be proved, the obtained time-histories data provides valuable incoming flow generating method to followed structure turbulence.2. Downburst wind fielda. Wall impinging jet modal can perfectly reflect the character of downburst wind field, the obtained numerical simulation result and empirical profile matches each other well.b. In the downburst wind field, horizontal wind speed in the radial wind profile will reach the maximum value at the distance of 1Djet from the center of the storm. Vertical wind speed in the radial wind profile will reach the maximum value at the height of around 80 meters from the ground, which is quite different from the character of atmospheric boundary layer.c. With the aid of sliding grid technique of CFD, the moving wall impinging jet modal numerical simulation can perfectly reflect the basic character of moving-type downburst wind field.