Stereo PIV/Shadowgraphy used to study bubble characteristics in turbulent flows

A combined PIV/Shadowgraphy setup has been used to investigate liquid and bubble motion in a grid-generated turbulent flow field. Simultaneous measurement of the liquid velocity flow field and bubble shape and rise velocity were performed for single- and multi-bubble systems at different turbulent energy inputs. Experiments were carried out for bubbles up to an equivalent spherical diameter of 10mm in both clean water and with surfactants present. It was found that the motion (rise velocity) of the bubbles was influenced by the level of turbulence and also by the presence of the surfactant. Further study is required with finer PIV resolution and higher recording rate to discern exact effect of the enhanced interface rigidity and the alteration of the vorticity field by the incident turbulence