Numerical boundary conditions at the interface in a confined flow computation

This study investigates the effects of the numerical zonal boundary conditions required for the computation in a confined flowfield which has been split into several zones (because of its complex geometry or computer capacity limitations) for reasons of computation convenience. A practical engineering problem of isothermal mixing flow is selected and the domain is split purposely into two computational subdomains for demonstration purposes. Three different approximations of the boundary conditions at the interface are examined and compared with the baseline predictions obtained with the overall computational domain. Comparison shows that application of the conventional, empirical inlet and outlet boundary conditions as the required zonal boundary conditions to the present practical problem gives poor prediction. A one-way coupling (parabolic) approximation slightly improves prediction accuracy in comparison with the use of conventional, empirical boundary conditions. A two-way coupling (zonal approaching) approximation yields the most satisfactory solution.