HIGH ACCURACY NUMERICAL APPROACH FOR NON-SIMILAR MIXED CONVECTION BOUNDARY LAYER FLOW OVER A HORIZONTAL PLATE

Abstract

The mixed convection boundary layer flow over a heated horizontal plate is studied using high accuracy numerical method. Present analysis is valid when the buoyancy force effects are small compared to forced convection effects. The mixed convection boundary layer equations are given with the buoyancy term represented by Boussinesq approximation. The non-similar mixed convection boundary layer equations are solved directly using direct integration method without any approximation for non-similar terms. Numerical results are reported for assisting and opposing mixed convection flows for air. Reported results show that both the local Nusselt number and local friction factor values are increasing with increase in buoyancy parameter for assisting mixed convection flows and decreases with increasing buoyancy parameter for opposing mixed convection flows. Reported results reveal that both the local Nusselt number and the local friction factor values are high compared to local similarity and local non-similarity methods for assisting mixed convection flows and less compared to local similarity and local non-similarity methods for opposing mixed convection flows. Reported results show that velocity and temperature profiles in the boundary layer are exactly matches compared to local similarity method for low value of buoyancy parameter (I¾). For assisting mixed convection flows, the significant buoyancy effects are encountered for I¾ ≥ 0.05 and the velocity exhibit an overshoot beyond the free stream velocity for high values of I¾. For opposing mixed convection flows, the effect of buoyancy is to reduce the velocity compared to pure forced convection. The thickness of thermal boundary layer decreases with increasing buoyancy parameter for assisting mixed convection flows and increases with increasing buoyancy parameter for opposing mixed convection flows. Present study provides an accurate numerical approach to solve non-similar mixed convection boundary flows. © 2010 by Begell House, Inc.