Sensitivity of Rotorcraft Hover Predictions to Mesh Resolution in Strand Grid Framework

Abstract

The strand grid approach is a flow solution method where a prismatic like grid using “strands” is grown to a short distance from the body surface to capture the viscous boundary layer and the rest of the domain is covered using an adaptive Cartesian grid. The approach offers a potential for nearly automatic grid generation and adaptation requiring very few input parameters while, at same time, offering the ability to obtain fast and efficient flow solution. This paper explores the sensitivity of rotor hover predictions to various meshing parameters in the strand grid framework. Surface mesh resolution has minimal impact on the predictions, whereas both the outer extent of the strand mesh and the Cartesian mesh resolution have significant effect on rotor performance and wake predictions. A strand mesh extending out to half a chord distance away and a Cartesian mesh spacing of less than two times the outer boundary spacing of the strand mesh are recommended for most rotor blade simulations.