Hystersis of turbulent stresses in wall flows subjected to periodic disturbances

The paper discusses some specific features of turbulent flows subjected to the periodic variation of external conditions. A particular emphasis is placed on the lagging response of turbulent structure and the hysteresis of turbulent stresses which were detected experimentally in a number of periodic flows. Experimental data were analyzed in this light, and attempts were made to obtain their prediction by means of single-scale and double-scale models of turbulence. Attention was focused on a case of simulated tidal flow where the above mentioned features are particularly pronounced. Some modifications of the standard stress-dissipation model of turbulence yielded a noticable improvement of the prediction of major properties of this and some other periodic flows.