Currently, structured-grid algorithms for solutions of the Navier-Stokes equations are particularly efficient but are restricted in their geometric flexibility. Unlike structured-grid methods, unstructured-grid methods can easily treat complex geometry configurations but have been found to be inefficient in viscous-dominated regions such as boundary layers because of the long, thin control volumes often countered in the boundary layer and the treatment of turbulence models. Therefore, the geometric flexibility of the unstructured-grid methods should be combined with the numerical accuracy and efficiency of the structured-grid methods. Hybrid methods can be used to efficiently obtain solutions for geometrically complex flow fields. This project will develop an efficient zonal-implicit algorithm for hybrid structured-unstructured grids. The reseFY 92 NASA ARCh will focus on implicit techniques for solving the Navier-Stokes equations on unstructured finite-volume grids and for zonal coupling between structured and unstructured grids. The zonal approach gives the user full control of the regions where unstructured-structured grids are applied. Phase I results will demonstrate the hybrid approach and Phase II will implement this approach in a production-version, three-dimensional Navier-Stokes code for solutions of complex configurations.
Potential Commercial Applications: The hybrid structured- unstructured grid-implicit algorithm results in both the geometric flexibility of unstructured grids for easy mesh generation and the numerical maturity and efficiency of structure-grids for complex flow physics. The code can be used efficiently as both a design and an analysis tool and will find a ready market in the aerospace industry and other industries.
