Two-phase flows involve more than one state of matter – in…

Two-phase flows involve more than one state of matter – in this case, both gas and liquid phases. Flows like this are common, especially in applications involving heat transfer. In some heat exchangers, bubbles will rise and then slide along an inclined surface, as shown above. The motion of these bubbles is a complicated interplay between the surface, the bubble, and the surrounding fluid. The bubble’s wake, visualized here using schlieren imaging, is unsteady and turbulent. Although the bubble oscillates in its path, the wake spreads even wider, and its turbulence stirs up the liquid nearby, increasing the heat transfer. (Image and research credit: R. O’Reilly Meehan et al., source)