Framework of Multiblock Structured Grid Smoothing Algorithms for Aircraft Configurations

Abstract

This paper presents the development of a new framework of multiblock structured elliptic grid smoothing for full-aircraft configurations. The framework is fully automated and applies different solvers on blocks based on their properties. Blocks with a solid wall are initialized by algebraic orthogonal grids and solved with a line SOR implicit elliptic solver. The remaining blocks are initialized by transfinite interpolation grids and solved with an SOR explicit elliptic solver. Both solvers apply spacing and curvature source terms. This combination results in orthogonal grids close to walls while imposing elliptic spacing and curvature control using variable relaxation factors in the field, including across the block boundaries. The orthogonality close to the solid walls is improved by using the properties of the initial algebraic orthogonal grids. The code is parallelized using Message Passing Interface for acceleration. The performance of the framework is demonstrated in a first step on 2D problems: a canonical test case and a multi-element high-lift airfoil. In a second step, the performance is analyzed on a full three-dimensional aircraft configurations (wing/body/engine) case at Bombardier Aerospace. The paper examines the effect of the proposed approach through various assessments of grid metrics and flow solver behaviors. In particular, the study highlights the improvements in reducing spurious drag through a far-field drag analysis.