Large-Eddy Simulations of Turbulent Flows around Buildings Using the Atmospheric Boundary Layer Environment–Lattice Boltzmann Model (ABLE-LBM)

Abstract

A three-dimensional, prognostic Atmospheric Boundary Layer Environment-Lattice Boltzmann Model (ABLE-LBM) using the multiple-relaxation-time lattice Boltzmann method was developed for large-eddy simulation of urban boundary layer atmospheric flows. In this article we describe the details of the ABLE-LBM for urban flow, its implementation of complex boundaries, and the subgrid turbulence parameterizations. As a first validation of this newly developed model, the simulation results were evaluated with two wind-tunnel datasets that were collected using particle image velocimetry and Irwin probes, respectively. The ABLE-LBM simulations use the same building layout and Reynolds numbers used in the laboratory wind tunnels. The ABLE-LBM simulations compare favorably to both laboratory studies in terms of the mean wind fields. The turbulent fluxes simulated by the model in the observational planes also agreed reasonably well with the laboratory results. The model produced urban canyon flows and vortices on the lee side and over the building tops that are similar to those of the laboratory studies in strength and location. This validation study using laboratory data indicates that our new ABLE-LBM is a viable approach for modeling atmospheric turbulent flows in urban environments. A numerical implementation using a graphics processing unit shows that real-time simulations are achieved for these two validation cases.

A GPU-Implemented Lattice Boltzmann Model for Large Eddy Simulation of Turbulent Flows in and around Forest Shelterbelts

“…The inflow mean wind speed was quite stationary at approximately 5.5 m/s at the height of 5.36 m. The LES simulation requires not only the observed mean wind profile of the approaching wind, but also the turbulent fluctuations for the inflow boundary condition. We used a simple synthetic algorithm [48] for the turbulence part of the inflow that agreed with the observed profile. The inflow boundary profiles are shown in Figure 3.…”

“…The numerical model used in this study is a newly developed microscale atmospheric boundary layer model that is called the atmospheric boundary layer environment-lattice Boltzmann model (ABLE-LBM). It is a four-dimensional prognostic LES model based on an MRTLBM [39][40][41][46][47][48]. It is used for fine-scale (temporal: seconds; spatial: meter to tens of meters) atmospheric boundary turbulent flows and the associated transport and dispersion of temperature, moisture, and other scalars (aerosol, smoke).…”

“…Instead of numerically solving the NSE, the LBM is a mesoscopic method that tracks the PDF of air parcel (or fictitious particle) motion and collision in certain prescribed sample directions that connect to neighboring computation grids. It can start with the evolution equation of the MRTLBE coupled with the forcing term [39][40][41][46][47][48]…”

“…All the model parameters and their physical representations, such as the relaxation coefficients matrix S, moment vector (m), equilibrium moment vector (m eq ), and the transformation matrix (M) are described in the work of d'Humières et al and Lallemand and Luo [40,41]. More detailed descriptions of the ABLE-LBM and its associated MRTLBM are available in the work of Wang et al [46][47][48].…”

“…To our knowledge, this is the first effort to develop and validate the capability of the MRTLBM in the simulation of a forest shelterbelt. We have developed an atmospheric boundary layer environment model using the MRTLBM, using this model to simulate the laboratory case of stratified turbulent flows over a ridge terrain [46] and around and overhead urban buildings [47,48]. The results show that this is an accurate and fast model for urban turbulent flow modeling using a graphical processing unit (GPU).…”