CHARACTERISTICS OF VISCOPLASTIC FLUID FLOW AT VARIOUS HEAT TRANSFER REGIMES ON THE WALLS OF A SUDDEN CONTRACTION CHANNEL

Consideration is given to the problem of laminar axisymmetric fl ow of viscoplastic fl uid in a channel with a sudden cross-sectional contraction under the conditions of a variable ambient temperature. A mathematical process model is presented that includes a vortex transfer equation, the Poisson equation for the stream function, and the energy equation with account for viscous dissipation. To describe the rheological properties of a fl uid, use is made of a modifi ed Schwedoff –Bingham model within whose framework account is taken of the dependence of apparent viscosity on temperature. In the course of solving the problem, the false transient method and the numerical fi nite diff erence methodology were employed. Two heat transfer regimes on the channel walls are investigated: in the fi rst case, a constant temperature value is assigned over the entire length of the wall, and, in the second case, a constant temperature is assigned on the walls in the vicinity of the inlet and outlet, and in the vicinity of the contraction plane, zero heat fl ux is assessed. The infl uence of thermal conditions on the structure of the fl ow and local pressure losses are assessed. The results of calculations in the form of distributions of fl ow characteristics as a function of the basic parameters of the problem are provided.
   
Author:  K. E. Ryl′tseva, G. R. Shrager
Keywords:  numerical simulation, channel contraction plane, viscoplastic medium, fl ow, viscous dissipation, boundary conditions, local resistance, unyielded region
Page:  649