Visualization of Bénard-Marangoni Convective patterns by Interferometry and Thermography

Abstract

In Bénard-Marangoni convection, both buoyancy and surface tension effects are involved, and beyond the onset of convection, polygonal cells are observed. Visualization of the convective patterns have been carried out using two methods, namely interferometry to visualize the free surface deformation field, and infrared thermography to visualize the interfacial temperature field. Images of the convective patterns were recorded at regular time intervals. The images were digitized, and appropriate software allowed us to obtain the values of the relevant functions. The two techniques are complementary. The thermography allows visualization of the entire pattern, including peripheral cells, whereas these cells cannot be visualized, by interferometry, due to the fact that this technique cannot be used in the region with a meniscus. For very thin oil layers, only thermography can be used. On the other hand, interferometry is more sensitive to the interfacial fluctuations, and therefore is better for the study of temporal dynamics in the flow.