Large-eddy simulation of an air curtain confining a cavity and subjected to an external lateral flow

In this work, large eddy simulations of a plane jet confining a cavity and subjected to an external lateral flow (ELF) were performed. Alongside and in a complementary manner an experimental study was carried out on a scale down model (1:5) representing a generic configuration of a display case, using LDV and PIV techniques to investigate the air flow characteristics. The jet behavior is examined using the mean velocity field, the turbulence characteristics, coherent structures by using the Q-criterion, and Strouhal number. The transport of a passive scalar was also considered to illustrate the dynamic interactions between the jet and its surroundings and thus, to better investigate the effect of the ELF on the transient jet behaviour. The statistical LES results will be analyzed and validated with the experimental results and a good agreement was achieved. The results are also compared with the standard k-ε model in order to achieve a critical evaluation of this model widely used in the studied configuration. Between the two numerical methods employed, LES performs better than RANS in predicting the jet behavior and jet characteristics. In addition, LES proves its ability to predict not only self-similarity properties, but also provide the pattern of large-vortex structures and their temporal evolution, and hence, successfully resolves the transient mixing process between the jet and its surroundings with and without external perturbation.