Effect of Inflow Boundary Conditions on the Solution of Transport Equations for Internal Flows

Abstract

A fully implicit numerical method for the solution of three-dimensional transport equations of fluid dynamics cast in generalized curvilinear coordinates has been enhanced to demonstrate the effect of inflow conditions on the downstream development of internal flow in a channel. The effect of inlet boundary conditions on turbulence kinetic energy (k) and the dissipation rate (�) on the downstream developing flow is investigated in terms of local values of k and Reynolds stress profiles. It is shown that the effect of inflow conditions lasts well over tens of channel heights downstream, before the flow eventually attains a fully developed state. This has an important bearing on turbulent flow (especially internal turbulent flow) simulation results where the characteristic dimensions of interest of engineering systems are much shorter. In some simulations, the solution sought may be in serious error if the inflow conditions chosen are not physically realistic. It is therefore important to account for the effect of wind tunnel inlet turbulence levels when comparing experimental data with predictions from a given external flow simulation. This study serves as a guide in the prescription of inflow