一类平衡大气边界层边界条件研究

基于标准k-ε湍流模型，首先利用湍流粘度方程和剪切应力在整个边界层内恒定的假设，推导出一类耗散率表达式，并根据常用的湍动能入口剖面方程以及平均风速剖面方程，计算获得相应的耗散率方程；然后在输运方程中添加自定义源项，通过已经确定的平均速度方程、湍动能方程、耗散率方程计算得到相应输运方程的自定义源项表达式，并进行空风洞数值模拟，从而得到了一类满足平衡大气边界层的来流边界条件．通过将这种边界条件与由湍流平衡条件得到的边界条件进行比较，表明本方法获得的边界条件更适用．并且，本方法无需考虑修正壁面函数和修正湍流模型常数，因而计算更为简单，可为平衡大气边界层的研究提供一种新的思路．

A Boundary Condition of Equilibrium Atmospheric Boundary Layers

A dissipation rate expression was derived in terms of turbulence viscosity equation and the assumption of constant shear stress in boundary layer, based on the standard k-ε turbulence model. Subsequently the dissipation rate equation was derived by using the common inlet turbulent kinetic energy equation and the mean wind velocity profile equation. Source terms were added in the transport equations and their expressions were calculated through the established average velocity equation, turbulent kinetic energy equation and the dissipation rate equation; a typical example of numerical simulation of an empty wind tunnel was conducted. In this way, a class of flow boundary condition was obtained to meet equilibrium atmospheric boundary layers. A comparison of it with those obtained from turbulence equilibrium conditions was made. The result shows that the former is more applicable. The modification of wall function and turbulence model parameters is avoided in the proposed method. Therefore, it is simpler in calculation, and further provides a new idea for the study of equilibrium atmospheric boundary layers.