Application of generalized Richardson extrapolation to the computation of the flow across an asymmetric street intersection

The validation of simulation results obtained from computational fluid dynamics (CFD) requires the estimation of the errors resulting especially from the spatial discretisation in space when steady solutions are computed. In this paper spatial discretisation errors are estimated with generalized Richardson extrapolation for the three mean velocity components at measurement positions within an asymmetric street intersection. The computational solutions are obtained with the code FLUENT V6.1 by solving the Reynolds averaged Navier–Stokes equations together with the standard k–ε turbulence model. From the solutions on five grids two grid triplets are formed, one with a constant refinement ratio of two and one with a smaller, nearly constant refinement ratio. From both grid triplets error estimates are possible for approximately 70% of the measurement locations. The resulting error bands agree fairly well, although the grid triplet with constant refinement ratio uses solutions from a substantially coarser grid than the triplet with non-constant refinement ratio. This fact is, however, correctly reflected by the larger error bands obtained for the grid triplet with the coarse grid solution which is most likely not in the asymptotic range.