Direct Building Energy Simulation Based on Large Eddy Techniques and Lattice Boltzmann Methods

The modeling of convective flows with 3D lattice Boltzmann fluid dynamics is presented using a lattice BGK approach for low Mach number flows with variable density combined with a large eddy turbulence model. The ability to resolve non− Boussinesq density varying problems is depicted for two dimensional Rayleigh−Bénard−convection at a Rayleigh number Ra = 800,000. A complex three−dimensional example shows the status of our work presenting turbulent flow in and around a building, so far without consideration of the energy equation in the 3D full scale case. Integrated within a CAD environment, the spatial geometric model, based on an IFC building product data model, is discretized using a hierarchic data structure. Results are presented for Re = 75,000 computed on a high−performance parallel vector computer. State−of−the−art visualization techniques integrate the simulation results into the CAD model in a virtual reality environment.