Computational Fluid Dynamics

Abstract

While CFD has been used for many applications in aerospace, biomedical research and electronics design, RWDI’s principal use of CFD is associated with flow issues in the built environment. We have used CFD to assist clients in the design of laboratories, clean rooms, schools, theaters, hospitals, sports complexes, and industrial facilities. Our modeling activities have included full scale cities (e.g. the Beijing CBD, Masdar, K.A.Care, Makkah, segments of Doha and San Francisco), along with natural ventilation of tall buildings, snow drifting in Antarctica, sand deposition on railway tracks, fires in atria, transit stations and tunnels as well as flows in double skin facades (DSF). We have also modeled flows in nuclear facilities, industrial processes and conducted component design with CFD. The advantage of CFD is that designers can easily interpret the predicted flow patterns shown on still and animated color images. Ironically, it is this ease that can lead to challenges with CFD modeling. The prediction of flow behavior in the build environment is complex as flow separation, time varying fluctuations and turbulence issues make interpretation of flow behavior challenging. The ease with which the color plots are generated from a simulation result is deceptive. In some flow regimes, e.g. around the outside of buildings in complex urban environments, CFD is too often treated as absolutely correct rather than treated with caution. Strategies to resolve this include the use of large eddy (LES) and detached eddy simulations, referred to as LES and DES respectively, approaching external flow CFD with background knowledge from wind tunnel testing, and knowledge of what questions CFD can answer.