Heat Transfer across a Solid‐Liquid Interface in the Presence of Acoustic Streaming

Experiments are described in which heat flow from a metal into a bathing liquid is measured in the absence and in the presence of acoustic streaming. The streaming is produced by a resonant vibrating air bubble resting on a solid plane, of which the heated metal forms a part. The temperature difference between the heated metal and the main body of surrounding fluid is kept constant. In these experiments, the heat flow rate is found to increase approximately linearly with the first‐order sonic amplitude when the liquid is water. Increases up to 10‐fold over the nonstreaming values of heat flow are obtained. When more‐viscous liquids (glycerin‐water mixtures) are used, the relationship between heat flow and sonic amplitude is non‐linear. In the latter situation, a region appears in which the flow rate decreases with increasing sonic amplitude. It is found that the decrease is associated with a reversal in direction of the streaming above the vibrating bubble. An order‐of‐magnitude theory is presented that gives rough numerical agreement with experiment and that predicts a linear relationship between heat flow and sonic amplitude.