Multigrid calculations of twin jet impingement with crossflow: Comparison of segregated and coupled relaxation strategies

The present study compares coupled and segregated relaxation operators with multigrid acceleration for the calculation of jet impingement flow fields. The symmetrical coupled Gauss-Seidel (SCGS) scheme and the SIMPLE algorithm have been used as relaxation operators. The coupled operator is observed to require less work for convergence than the segregated method. When additional scalar equations were solved, the segregated method exhibited a definite deterioration in convergence rate. The coupled method revealed similar behavior as regards the solution of turbulence equations. Unlike the segregated operator, the convergence of the coupled operator did not deteriorate with the addition of the energy equation for high temperature flow calculations. The calculations performed in these tests required cell aspect ratios as large as sixteen in order to resolve important flow features. The SCGS operator provided rapid convergence even when these aspect ratios were used.