Parallel Solution-Adaptive Method for Two-Dimensional Non-Premixed Combusting Flows

A parallel adaptive mesh refinement (AMR) algorithm is proposed and applied to the predictions of both laminar and turbulent steady non-premixed compressible combusting flows. The parallel solution-adaptive algorithm solves the system of partial-differential equations governing two-dimensional axisymmetric laminar and turbulent compressible flows for reactive thermally perfect gaseous mixtures using a fully coupled finite-volume formulation on body-fitted multi-block quadrilateral mesh. The compressible formulation can readily accommodate large density variations and thermo-acoustic phenomena. A local preconditioning technique is used to remove numerical stiffness and maintain solution accuracy for low-Mach-number, nearly-incompressible flows. A preconditioned multigrid algorithm is used for the efficient solution on highly stretched meshes. A flexible block-based hierarchical data structure is used to maintain the connectivity of the solution blocks in the multi-block mesh and facilitate automatic solution-directed mesh adaptation according to physicsbased refinement criteria. This AMR approach allows for anisotropic mesh refinement and the block-based data structure readily permits efficient and scalable implementations of the algorithm on multi-processor architectures. For calculations of near-wall turbulence, an automatic near-wall treatment readily accommodates situations during adaptive mesh refinement where the mesh resolution may not be sufficient for directly calculating near-wall turbulence using the low-Reynolds-number formulation. Numerical results for co-flow laminar and turbulent diffusion flames are described and compared to available experimental data. The numerical results demonstrate the validity and potential of the parallel AMR approach for predicting both fine-scale features of laminar and complex turbulent non-premixed flames.