turbulent heat and mass transfer through air curtains devices for the confinement of heat inside tunnels

the influence of flow instabilities on the efficiency of a twin-jet air curtain formed by a cold stream parallel to a hot stream was studied. two cases were considered: the reynolds number and mean flow velocity of both streams were set to 1000 and 3 m/s, respectively. the results obtained from 3d les simulations were compared with experimental data and earlier les numerical results using the fds code. energy spectra exhibit decay laws with − 5/3 and − 3 slopes. instabilities with a characteristic strouhal number of about 0.4 were detected. kelvin–helmoltz type instabilities play a more significant role than the görtler type instabilities present at the wall for applications of plane impinging jets to ambience separation.