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Turbulent wind flow over buildings occurs due to the complexity like sharp corners, ground effect and different vortexes is one of the best choices to evaluate turbulence methods. DES and DDES are hybrid RANS-LES models for simulating turbulent flow which for their characteristic treat near wall as RANS and farther the wall act as LES model. Consequently computational time will decrease compared to traditional LES models. In this article to evaluate DES and DDES models, turbulent incompressible flow in Re = 22000 over 3D building is simulated using parallel processing facilities. For verification purpose other investigators experiment results are used. Also the mentioned models are compared with classic RANS and LES models, like k-ε and LES-Smagorinsky to depict their performance. Our results illustrate DES model with fine grid has good precision for simulating turbulent incompressible wind flow over building and decline of 26 percentage of computational time compared to LES-Smagorinsky model.

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Predicting wind flow pattern around high rise building, because of pedestrian comfort, air pollution in weak wind region and etc. has important position in wind engineering. Turbulent wind flow over buildings due to the complexity like sharp corners, ground effect and different vortexes, is one of the best choices to evaluate turbulence methods. Moreover in a campus due to high velocity region between buildings, simulating wind flow is more complex. Therefore reaching acceptable result needs a fine grid with an accurate turbulence model that increases computational cost. DES is hybrid RANS-LES models for simulating turbulent flow which for their characteristic, treat near wall as RANS and farther the wall act as LES model. Consequently in this hybrid model, computational time will decrease compared to traditional LES models. In this article turbulent 3 dimensional wind flow over Tarbiat Modares University with DES method in different wind velocities is simulated. Because cells number is great, parallel processing has been used. For verification, DES results are compared with traditional LES models such as smagorinsky. The results show good agreement with other traditional methods.