Heat transfer in turbulent flow with separation

Abstract

The Reynolds analogy, which states that the wall friction is proportional to the heat flux, is not valid for flow separation regions, since then 3u/~y -O, while in some cases the heat flux reaches values even greater than in reattached flow. It is expedient to use the turbulent energy balance equation to calculate heat transfer in separated flows. In spite of the fact that in separated flow the friction stress at the wall is zero, the turbulent energy intensity in the flow is large; the turbulence diffuses towards the wall and, in particular, accounts for the intense heat transfer. The one-dimensional turbulent energy balance equation for separated flow was considered in [i], where the authors analyzed the limiting case of flow separation where there is no turbulent energy production (rdu/dy = 0) throughout the entire flow. It is interesting to consider the case of a linear distribution of friction stress across the flow, with zero stress at the wall. This distribution, as was pointed out in [2], agrees with experimental data for separated flow.