Visualisation of the wake behind a sliding bubble

In this work, Schlieren measurements are presented for the wake of an air bubble sliding under a heated, inclined surface in quiescent water to provide new insights into the intricate sliding bubble wake structure and the associated convective cooling process. This is a two-phase flow configuration that is pertinent to thermal management solutions, where the fundamental flow physics have yet to be fully described. In this work, we present a novel experimental apparatus that enables high quality Schlieren images for different bubble sizes and measurement planes. By combining these visualisations with an advanced bubble tracking technique, we can for the first time simultaneously quantify the symbiotic relationship that exists between the sliding bubble dynamics and its associ- ated wake. These findings, along with their implications from a thermal management perspective, provide information on the rich dynamics of this natural flow that cannot be obtained using alternate experimental techniques.