Turbulenter Wärme‐ und Stoffaustausch

Abstract

AbstractTurbulent heat and mass transfer. Turbulent heat and mass transfer is inseparably connected with turbulent momentum transfer. Thus we again find the same problems as those encountered in the description of turbulent momentum transfer. Moreover, further difficulties arise because of the temperature and concentration fluctuations in addition to the velocity and pressure fluctuations. The problems are essentially experimental ones. It is much simpler to measure correlations of velocity fluctuations like the turbulence energy or the Reynolds shear stress than correlations of other fluctuating quantities. This is why attempts were made at an early stage to reduce the turbulent heat and mass transfer to the comparatively well understood turbulent transfer of momentum. Therefore the basic ideas concerning the modelling of the turbulent momentum flux are discussed at first. A brief introduction to concepts of the statistical theory of turbulence is also given. Finally some proposals to describe the turbulent heat transfer based on modelling assumptions are presented for example of turbulent tube flow. Turbulent mass transfer is only briefly touched upon because of the far greater experimental gaps opposing reliable modelling.