Numerical calculation of nonisothermal laminar flow around a circular cylinder wrapped with a permeable ring

Abstract

Modern technologies allow to create new porous materials with the different matrix structure. One of the areas of their practical use is to apply to the body a porous permeable ring to intensify heat transfer or alternatively, for thermal insulation. In this paper the separated nonisothermal flow of a viscous incompressible fluid around a circular cylinder coated with a porous permeable layer with a given thickness is investigated numerically at moderate Reynolds numbers. The layer is made of high thermal conductivity and thermal insulation materials. To describe the fluid motion used non-stationary Navier-Stokes and energy equations. It is assumed that the material permeable layer has a corpuscular structure. The filtration flow in the porous layer is determined by the non-linear two-term Ergun law, which takes into account the inertial effects. In the numerical experiments varies of Reynolds number and Darcy number. The drag coefficient of the body, the length of the vortex wake, the surface temperature of the porous layer, the Nusselt number calculated. It is found that the flow separation can be observed with both core and surface layer depending on the permeability. The length of the vortex area increases with increasing Reynolds number and decreases with increasing Darcy number. The effect of matrix permeability and thermal conductivity of the material on the heat exchange of the body and the liquid is analyzed.