Numerical Simulation Of Equilibrium Atmospheric Boundary Layer Based On RANS Model

When using CFD software to simulate the around flow of buildings in the atmospheric boundary layer,specific inflow boundary conditions are given.When the flow has not arrived at building,significant changes of key parameters have taken place,which will reduce the accuracy of the simulation results.So,using numerical simulation method to study the interaction between buildings and atmosphere must verify whether flow conditions can remain and whether the buildings is in the balance of the atmosphere boundary layer,only in this way the calculation results can be more accurate.The key to the study of equilibrium atmospheric boundary layer is the matching between inflow condition,turbulence model and wall condition.So in order to achieve the stable atmospheric movement,this article study from three aspects: Firstly,an of average wind speed,turbulence kinetic energy and dissipation rate is deduced from a set of assumption,and this kind of inflow condition can conform to the reality;Secondly,through the study of turbulence model wall function,choose the reasonable wall function of the ground roughness and turbulence model matching to flow under the condition of boundary conditions and gravel type roughness correction of wall function;Thirdly,by studying the turbulent transport equation of the standard k-ε turbulence model,the diffusion items of turbulent kinetic energy and dissipation rate are derived as source items to be added to the transport equation.Finally,based on the equilibrium atmospheric boundary layer,the wind pressure distribution of low building surface is studied,and the applicability of the work is verified by comparing with the field measurement and wind tunnel test results.