EFFECTS OF HEATING MODE ON STEADY AXISYMMETRICAL THERMOCAPILLARY FLOWS IN MICROGRAVITY

Steady thermocapillary flows in cylindrical containers with unit aspec t ratio (radius = depth) are studied numerically and by scaling analys is in order to investigate how the velocity and thermal fields are inf luenced by the method of heating. Two heating modes are considered: he ating by a uniform temperature cylindrical heater placed along the cen terline (called the CT heating) and heating by an external radiative s ource (the CF heating). The steady velocity and temperature fields are computed numerically under various conditions for various Prandtl num ber fluids. The effects of those two types of heating on the flows are discussed. The results are also found to support the scaling laws der ived herein for the characteristic velocity, length, and Nusselt numbe r. The main thermocapillary driving force region is fixed by the heati ng cone area in the CF heating but it generally varies with the pow in the CT heating.