Paper Conference

Proceedings of ASim Conference 2014: 2nd Asia conference of IBPSA-China, Japan, Korea


Predict the quality of outdoor thermal environment with equivalent transformation of thermal boundary condition models

Wenbin Hu

Abstract: As a worldwide used commercial CFD software, FLUENT, with later version combined with solar model, has comparablly robust computational core for airflow and solar radiation. However, for complex heat exchange between airflow and urban underlying surface, FLUENT with built-in boundary condition models has obvious deficiency in the discription of heat balance of urban underlying. Based on the form of mixed boundary condition model included in FLUENT, this paper proposes equivalent absorptivity coefficient to describe the absorption of solar beam radiation with the consideration of vegetation shadow and evaporation cooling effect. This paper also presents equivalent form for convective heat transfer between surface and free sream flow, combined with heat flux into building interior zone and underground soil. For long wave radiant heat transfer from surface to sky and ground, this paper puts forward equivalent form suitable for FLUENT radiation boundary condition model. Compared with experimental data of underlying surface temperature in a residential district, equivalent transformation of thermal boundary condition model is validated.
Keywords: Computational fluid dynamics simulation, Quality of outdoor thermal environment, Equivalent transformation of thermal boundary condition models
Pages: 220 - 227