Numerical modeling of turbulent dispersion around structures using a particleincell method
Abstract
A methodology is described wherein two numerical models are exercised in order to predict the turbulent transport and dispersion around a surface mounted rectangular block. This methodology can be expanded in the future to treat more irregularly shaped single buildings or clusters of buildings. The calculational procedure which is proposed consists of two separate steps, namely: (1) prediction of the turbulent wind field and (2) employment of the calculated wind field to drive a transport dispersion model. It is well known that external flow past nonstreamlined bodies is usually very complex, exhibiting separation and reattachment regions, high pressure gradients and turbulence levels, and unsteadiness. The approach employed is to solve the Reynoldsaveraged Boussinesq equations with turbulence represented via a k(epsilon) model. This particular turbulence model has been applied extensively to many classes of flows including those which are influenced by buoyancy, stratification and rotation effects. It has a good reputation for reliability and is also computationally economical compared to more complex models. Recently, a number of calculations of turbulent flows over surface mounted cubes which use a k(epsilon) turbulence model in conjunction with finite difference techniques were presented. In contrast, the flow model developed uses a modified finite element method (FEM). A KTheory version of this model was employed to simulate flows which describe the dispersion of heavierthanair gases and the atmospheric boundary layer. The present model is algorithmically identical to the earlier model except two additional equations were required for the turbulence model and a buildingblock specification is used to represent structures for computational efficiency.
 Publication:

NASA STI/Recon Technical Report N
 Pub Date:
 1991
 Bibcode:
 1991STIN...9123426L
 Keywords:

 Atmospheric Boundary Layer;
 Flow Distribution;
 KEpsilon Turbulence Model;
 Particle In Cell Technique;
 Pollution Transport;
 Turbulent Flow;
 Wind Profiles;
 Air Pollution;
 Boussinesq Approximation;
 Computational Fluid Dynamics;
 Dispersing;
 Finite Element Method;
 Reliability;
 Simulation;
 Turbulence;
 Fluid Mechanics and Heat Transfer