Petter Vollestad: Microscale wave breaking and airflow separation in stratified two-phase pipe flow

Title: Microscale wave breaking and airflow separation in stratified two-phase pipe flow

by: Petter Vollestad, matematisk institutt, UiO.

Abstract: We perform an experimental study of stratified gas-liquid pipe flow with the aim to detect small-scale wave breaking and its influence on both the gas and liquid phase. Particle image velocimetry (PIV) is applied simultaneously in the two phases, and a criterion based on the vorticity in the crest region is used to detect microscale breaking waves. Airflow separation is frequently observed, and the study aims to investigate the correlation between small scale wave breaking and airflow separation above waves.  Results indicate that at moderate gas flow rates, microscale wave breaking has a stabilizing effect on the airflow above waves, reducing the sheltered region in the lee of the wave crest and the turbulence directly above the waves. At higher gas flow rates, no influence of wave breaking on the airflow is observed.