Application of strand meshes to complex aerodynamic flow fields

Abstract

We explore a new approach for viscous computational fluid dynamics calculations for external aerodynamics around geometrically complex bodies that incorporates nearly automatic mesh generation and efficient flow solution methods. A prismatic-like grid using “strands” is grown a short distance from the body surface to capture the viscous boundary layer, and adaptive Cartesian grids are used throughout the rest of the domain. The approach presents several advantages over established methods: nearly automatic grid generation from triangular or quadrilateral surface tessellations, very low memory overhead, automatic mesh adaptivity for time-dependent problems, and fast and efficient solvers from structured data in both the strand and Cartesian grids.The approach is evaluated for complex geometries and flow fields. We investigate the effects of strand length and strand vector smoothing to understand the effects on computed solutions. Results of three applications using the strand-adaptive Cartesian approach are given, including a NACA wing, isolated V-22 (TRAM) rotor in hover, and the DLR-F6 wing-body transport. The results from these cases show that the strand approach can successfully resolve near-body and off-body features as well as or better than established methods.