Turbulence model

It is well known that humidity influences cooling load, thermal comfort and durability of buildings and various items in them. Many works on prediction of humidity variation in a room have regarded the humidity as unique in a space. However, it does depend on air movement. This paper describes calculations of minute moisture distributions in a room affected by moisture buffering of porous walls. The air velocity distribution is calculated by CFD using two different turbulence models. Then the heat and vapor transient transport in walls and space is calculated.

The prediction of plume dispersion near buildings is very important for the design of exhaust stacks andair intakes in order to avoid adverse air quality impacts. However, it is difficult to predict pollutantdispersion with certain accuracy due to the complex interaction between atmospheric flow and flowaround buildings.

In order to simulate indoor air distribution and airflow around buildings quickly and accurately by CFD (Computational Fluid Dynamics) technique, a new zero-equation turbulence model and momentum method for inlet boundary condition are adopted. The new version of STACH-3, a three-dimensional CFD software is developed based on these. An example for outdoor airflow around an isolated building is given as well. For those high-density buildings with complex geometry, the TSM (Two Step Method) is proposed.