Steady RANS model of the homogeneous atmospheric boundary layer

Abstract

A computational model was proposed to simulate the homogeneous atmospheric boundary layer (ABL) above rural, suburban and urban flat terrains for the neutral thermal stratification of the atmosphere. This is achieved using the steady Reynolds-averaged Navier-Stokes equations and the standard k-ε turbulence model. The major feature of the proposed approach is the implementation of the wind-source term in the momentum equation, which is adjusted using the experimental wind-tunnel data. Profiles of the mean velocity, turbulent kinetic energy and Reynolds shear stress are homogeneous along the computational domain. The mean discrepancy in the longitudinal direction is 0.1% for the mean velocity profile, 0.6% for the Reynolds shear stress profile, 0.3% for the turbulent kinetic energy profile. The preliminary results show good agreement between the computed profiles and the ABL wind-tunnel simulations, as the mean discrepancy between the experimental and computational results is 4.5% for the mean velocity profile, 2.5% for the Reynolds shear stress profile, 6% for the turbulent kinetic energy profile. The surface pressure distribution at the cubic building model subjected to the suburban ABL flow indicates characteristic patterns in accordance with the respective flow phenomena, i.e. flow separation and reattachment, stagnation zone, leeward suction. The results show that the calculated wind-source term does not have a significant influence on the aerodynamic loads on the cubic building model, whereas it ensures homogeneity of the boundary layer flow properties throughout the computational domain in agreement with the wind-tunnel results.