AN EXPERIMENTAL-STUDY OF FREE-SURFACE DEFORMATION IN OSCILLATORY THERMOCAPILLARY FLOW

Free surface deformation of a test fluid induced by steady and oscilla tory thermocapillary flow in a small cylindrical container (diameter = 4.8 mm) is studied experimentally. The fluid (2 Cs oil) is heated by a cylindrical wire (diameter = 0.48 mm) placed along the centerline of the cylinder. The relative displacement and oscillation frequency of free surface are measured in a radial cross-section for various applie d temperature differences. It is found that the amplitude of the free surface height oscillations is large near the heater and the cold wall and relatively small in the middle part. The frequency of the free su rface oscillations is same as the frequency of the temperature oscilla tions. Based on these data, the free surface motion during oscillation s is delineated.