CFD simulation of flow field around and within a cross-ventilated building
The geometric model
Natural ventilation has been increasingly important in architecture design, as it is an environmentally friendly strategy to improve the indoor air quality by effectively using the natural winds around buildings. Since it is a sustainable technology, integrating natural ventilation into building design has been very popular among architects and engineers. However, the interactions between the wind pressures acting on the openings and the indoor airflow field are very complicated owing to turbulent flows. In order to enhance the understanding of the complicated flow field, a cross-ventilated model has been made, where two openings are created to allow the airflow in and out.
Profiles of approaching wind
The velocity profiles of the approaching wind were made according to the experimental data gathered in the wind tunnel test. The mean velocity profile was approximated by a traditional "power-law" model with an exponent of 0.25. Turbulence quantities of the wind were also specified in accordance with the wind tunnel data. The profile of the turbulent kinetic energy was approximated by a polynominal function to the 4th order.
The mesh
There are 570,564 hexahedral cells in the computing domain and the minimum spacing of the cells near walls were in the range of 30 < y+ < 130 (log-law layer). A second-order upwind differencing scheme was used to calculate the velocity variables and the turbulence quantities on the cell faces.
Results
The results can be presented in two parts:
Part 1: Validation
Animation
The motion of the airflow around and within the cross-ventilated building has been simulated by DES (detached eddy simulation). The unsteady flow simulation can capture more flow features such as the vortex shedding and the time-dependent variation of the flow pattern.
Animations (click the preview for animation)