Flow field and particle dispersion in a naturally ventilated model building: Application of large eddy simulation based on parallel lattice Boltzmann method

Abstract

Flow field analysis and pollutant particles tracking in a natural ventilation flow are computationally intensive due to the coupled outdoor and indoor airflow, as well as the existence of different turbulence scales, and large numbers of particles. As a breakthrough approach, an explicit and parallel algorithm based on lattice Boltzmann method (LBM) solver is developed to simulate transient particulate flow indoor and outdoor of a model building. Since flow analysis in natural ventilation requires high-order CFD methods, large eddy simulation (LES) by the wall-adapting local eddy-viscosity (WALE) sub-grid scales model is employed. Also, one-step collision for reduction of memory usage, domain decomposition method for parallel processing of both flow and particles, and Lagrangian tracking for following particles are implemented into the developed algorithm. Investigation of grid independency shows that medium lattice resolution provides an average mean deviation equal to 18% and 34% for horizontal and vertical centerline of model building, respectively. In addition, when compared to finite volume method (FVM), LBM requires 2.7 times higher lattice resolution to achieve acceptable accuracy. However, it approximately speeds simulation duration up to 3 times. Moreover, 100 seconds of parallel particle tracking lasts almost 800 minutes on a simple desktop.