Can Simultaneous PIV In The Gas And Liquid Phases Provide Insight Into The Transfer Of Momentum Between The Two Phases?

Understanding the interaction between a gas shearing over a liquid film and the liquid film is essential if we wish to use modeling to optimize systems to decrease environmental impact, increase efficiency and hence productivity. To this end, PIV is used t o simultaneously study the velocity fields in the gas and liquid fields to better understand the interaction between the two phases.  The methodology is detailed in the paper and initial results show that the film shape changes as the flow increases from 2 .2 m/s to 4.7 m/s. This change can be seen to be from a 2D surface wave regime to a 3D wave regime. In the 2D regime, the liquid film is linear in shape and the averaged and conditionally averaged velocity profiles of the gas and liquid velocity are equal at the interface.  In the 3 D regime, the averaged liquid and gas velocity profiles are no longer equal at the average interface height. Instead, they coincide at the 2.5% percentile of the local height distribution. The conditionally averaged velocity profiles show significant differences as the film height changes.  It is suggested that this would mean the use of average profiles for validating CFD in similar situations might need to be reviewed.