Capability Enhancements in Version 3 of the Helios High-Fidelity Rotorcraft Simulation Code

Abstract

This paper presents an overview of new capabilities in the Helios v3, or Rainier, highfidelity rotorcraft simulation software. Key new capabilities include the addition of DES turbulence modeling in the near-body solver and RANS in the off-body solver, introduction of Richardson extrapolation-based error control to automate off-body AMR, and runtime parallel partitioning of near-body grids. We also report on advances made in Helios to support loose-coupling rotor-fuselage and multi-rotor configurations. The paper describes these capability enhancements in detail and provides validation results and computational performance metrics for the model TRAM rotor, HART-II, and UH-60A configurations.

An Adaptive Explicit 3D Discontinuous Galerkin Solver for Unsteady Problems<br />

“…This subsection describes the integration of the first term of the residual in equation (4). First noting that the mesh discretization is time-independent, we may factor the time derivative out of the integral.…”

“…This subsection describes the integration of the second term of the residual in equation (4). The volume integral is a disjoint sum of three flux integrals:…”

“…Cartesian meshes represent the simplest grid structure which can be represented extremely compactly, thus minimizing solver memory footprints, optimizing parallel efficiency, and simplifying both adaptive mesh refinement implementations 1, 2 and overset mesh search and interpolation tasks. 3,4 The principal drawback of Cartesian mesh approaches lies in the difficulties of dealing with non-simple geometries. Various approaches for dealing with complex geometries have been developed for use with Cartesian meshes including immersed boundary methods, 5, 6, 7 cut cell approaches, 8,9,10 and overlapping dual mesh paradigms where a body fitted mesh is used in near-body regions and a Cartesian mesh is used in off-body regions.…”

“…Various approaches for dealing with complex geometries have been developed for use with Cartesian meshes including immersed boundary methods, 5, 6, 7 cut cell approaches, 8,9,10 and overlapping dual mesh paradigms where a body fitted mesh is used in near-body regions and a Cartesian mesh is used in off-body regions. 3,4,11 The development of high-order accurate discretizations for computational aerodynamics has been pursued vigorously over the last decade and substantial advances have been demonstrated for continuous and discontinuous Galerkin (DG) methods. 12,13,14,15,16,17,18,19,20 However, the use of high-order methods for computational aerodynamics remains a research topic largely due to the poor robustness and large computational expense of these methods.…”

Application of Strand Grid Framework to Complex Rotorcraft Simulations

“…Over the past several years a number of developments have gone into Helios to enhance automation, including automatic off-body adaptive mesh refinement, 6, 10 automatic implicit hole cutting, 7 simplified GUI with default solver options 11 and co-visualization to reduce data output primarily to simplify post-processing. 3 At present, generation of viscous near-body grids remains one of the barriers to full automation of Helios.…”