Simulation of air curtains for vertical display cases with a two-fluid model

In a vertical open display case, air curtains are used to weaken the influence of ambient air on the store. The flow and heat transfer characteristics of air curtains in a vertical display case are simulated with a two-fluid turbulence model in this paper, which takes the fluid in the space to be simulated as a mixture of turbulent fluid and non-turbulent fluid. The air curtains are taken as a turbulent fluid and described by the conventional k–ε turbulence model. The ambient air outside the display case is considered as a non-turbulent fluid and calculated by a laminar model. The exchanges of mass, momentum and energy between the turbulent and the non-turbulent fluids are expressed by empirical relations. The simulation results based on the two-fluid model are compared not only with experimental data, but also with the simulation results when the k–ε model is used for the whole simulated space. The comparisons indicate that the two-fluid model enables to predict thermal stratification phenomenon more accurately and shows better agreement with the measured values than the k–ε model.