Thermophoretic transport and deposition of particles in vertical tube flow with variable wall temperature and thermal radiation

A particulate two phase flow with variable wall temperature has been studied for examining the deposition of particles in the thermal radiation and mixed convection flow associated with the manufacture of optical fiber preforms. The two-dimensional governing equations of continuity, momentum and energy have been solved numerically including the effects of thermal radiation and buoyancy (upward or downward flow) in the vertical tube flow. A particle trajectory model has been adopted to predict the particle transport, and P-1 approximation has been used to evaluate the radiation heat transfer. In the upward flow case, a high deposition efficiency is obtained and the deposition zone of the downward flow is broader than that of the upward flow. Thermal radiation makes the deposition zone broader and the deposition efficiency smaller.