Plasma flow over an array of particles

This paper presents an analysis of heat and momentum transport to an array of particles from a flow of a collision-dominated weakly ionized gas consis ting of electrons, ions, and neutrals. The particle longitudinal and latera l spacing is varied independently to study the effect of:particle spacing o n the flow and heat transport. The conservation equations for mass, momentu m, and energy for the neutrals and those for ions and electrons are solved simultaneously with the Poisson's equation for the self-consistent electric field. Solutions are obtained using a finite volume method and the formula tion is based on a cylindrical-cell model. An orthogonal adaptive grid is g enerated to body-fit the particle surfaces as well as the cylindrical outer boundary of the cell envelop. The flow field and the temperature distribut ions are obtained in the plasma and the overall Nusselt number and the drag force acting on each particle are determined. Results indicate that the ho w and transport around a given particle is significantly influenced by the presence of the neighboring particles. An increase in the lateral spacing b etween particles results in a decrease in the Nusselt number as well as the drag coefficient, whereas increasing longitudinal particle spacing leads t o an increase in both the Nusselt number and the drag coefficient. The effe ct of side particles becomes negligible for lateral spacings greater than a bout five diameters. However, the influence of upstream particles remains s ignificant even at longitudinal particle spacing of five diameters. Correla tions that incorporate the effects due to neighboring particles have been p roposed for the drag coefficient and the Nusselt number of an interior part icle in the array. (C) 1999 Elsevier Science Ltd. All rights reserved.