HYDRODYNAMIC CONTROL OF GAS-PHASE THICKNE SS OF SEMICONDUCTORS DEPOSITED ON ROTATIONALLY SYMMETRICAL BODIES IN MIXED CONVENTION

The authors solve using an finite difference method the equations of s teady-state laminar boundary layer around a body of revolution (sphere , extended and flattened ellipsoids). Hydrogen gas at 25 degrees C flo ws upward around the body. Its nose faces downward, the temperature of its surface is 500 degrees C and it rotates about its vertical axe at a constant velocity. The variability of the physical properties of th e fluid as a function of temperature is considered as well as the resu lting natural convection. It is revealed that flow, heat and mass tran sfers depend of the physical properties of the gas. It is possible to control the development of thermal and diffusional boundary layers thr ough the operational conditions, specially the contour of the body.