نشریه مهندسی دریا (Sep 2015)
Numerical Modelling of Non-isotropic Stratified Flows Using an Explicit Algebraic Reynolds Stress Turbulence Model (EARSM)
Abstract
Flows of natural hydro-environments are usually turbulent and mostly stratified, like the flows in lakes, reservoirs, estuaries and atmosphere to name a few. In stratified flows due to the buoyancy forces, the turbulent stresses are usually non-isotropic. Therefore the accuracy of the numerical simulations for such flows is highly dependent on the turbulence model and the implementation of non-isotropic stresses. The hydrodynamic model deployed herein is the 2DV WISE (Width Integrated Stratified Environments) numerical model. In this paper an explicit algebraic Reynolds stress model together with an explicit algebraic scalar flux model have been developed and implemented in the original hydrodynamic model. To validate the EARSM turbulence model, lock release tests have been simulated for saline and dense stratified flows. The predicted values of the evolution and the front head position of the stratified flow, and the velocity profiles simulated by EARSM model have been compared against the measured values reported in the literature and the predicted results of the buoyant k-;epsilon model originally included in the hydrodynamic model. The comparisons indicated good performance of the EARSM turbulence model and showed its superiority compared to the k-;epsilon turbulence model in these regions.
