摘要

A mathematical model is presented for laminar free convection boundary-layer flow of a Casson viscoplastic non-Newtonian fluid external to a vertical penetrable circular cone in the presence of thermal and hydrodynamic slip conditions. The cone surface is maintained at a nonuniform surface temperature. The boundary layer conservation equations, which are parabolic in nature, are transformed into nondimensional form via appropriate similarity variables, and the emerging boundary-value problem is solved computationally with the second order accurate implicit Keller-box finite-difference scheme. The influence of velocity (momentum) slip, thermal slip, and Casson non-Newtonian parameter on velocity, temperature, skin friction, and Nusselt number are illustrated graphically. Validation of solutions with earlier published work is included. The computations show that the flow near the cone surface is strongly decelerated with increasing momentum slip whereas the temperature and thermal boundary-layer thickness increased. Increasing Casson parameter generally decelerates the flow and also decreases temperatures. Both velocity and thermal boundary-layer thickness are reduced at a higher Prandtl number. The study is relevant to petrochemical engineering (polymer) processing systems.