Boundary Conditions

Computational fluid dynamics (CFD) is a promising method to study the urban built environment. However, the pecularities of the urban wind environment are difficult to simulate with a CFD package. The aim of this work is to develop CFD model capable of simulating the urban boundary layer which can then be used to investigate the effects of built form on the pressure coefficient regeme. The model concentrates on two aspcepts: the boundary conditions and domain size.

The intention of this paper is not to compare discretization schemes but to show some advantages of a stabilized finite element method for modelling natural ventilation. Based on the finite element theory we present a formulation of boundary conditions that can be used for most ventilation openings in buildings. Stationary as well as transient situations can be considered without modelling of the outdoor space. Mathematical background and implementation details are discussed. Results are presented for ventilation of a living room at typical outdoor conditions.