Rapid Time Varying Ventilation Flow Rates as a mean of increasing the Ventilation Efficiency

The paper reports on findings from a series of experiments where the supply flow rate wasvaried periodically in time. All experiments were conducted in a small scale model with water as operating fluid. The flow was visualised by adding particles to the water and the streaks were recorded with a digital camera. The main result is that there exist variations that generate a role up of the base flow by generation of vortices that are shed into the stagnant region.