A Multi-Code Python-Based Infrastructure for Overset CFD with Adaptive Cartesian Grids

Abstract

This paper describes a computational infrastructure that supports Chimera-based interfacing of different CFD solvers-a body-fitted unstructured grid solver with a blockstructured adaptive cartesian grid solver-to perform time-dependent adaptive movingbody CFD calculations of external aerodynamics. The goal of this infrastructure is to facilitate the use of different solvers in different parts of the computational domain-body fitted unstructured to capture viscous near-wall effects, and cartesian adaptive mesh refinement to capture effects away from the wall. The computational infrastructure, written using Python, orchestrates execution of the different solvers and coordinates data exchanges between them, controlling the overall time integration scheme. Details about the infrastructure used to integrate the codes, the parallel implementation, and results from demonstration calculations are presented.

Overview of the Helios Version 2.0 Computational Platform for Rotorcraft Simulations

“…[3][4][5][6] The dual-mesh paradigm that is the basis of the Helios aerodynamics solution procedure consists of unstructured meshes in the near-body region and block-Cartesian meshes in the off-body region 5 (see Fig. 1).…”

“…A light-weight and flexible Python-based infrastructure is used to combine the different solver components such as the near-body solver, off-body solver, domain connectivity formulation and comprehensive analysis component. 4 Python run-mode scripts serve to control the execution of these components and the data transfer between them.…”

Automated Off-Body Cartesian Mesh Adaption for Rotorcraft Simulations

“…To address the difficulties of accurate far-field wake resolution, Helios employs a dual-mesh overset flow solution approach comprised of an unstructured solver operating on the near-body prism/tetrahedral grid and a high-order adaptive Cartesian solver operating on the off-body wake domain. 15,16 The two solvers are coupled using an overset domain connectivity algorithm that applies implicit hole cutting and adds fringe regions to allow for relative grid motion.…”

Assessment of Tip Shape Effect on Rotor Aerodynamic Performance in Hover

“…The solver showed abilities in solving various rotor aerodynamic problems, but complex geometry modeling is still difficult and is time-consuming due to the nature of the structured grids. Recently, a hybrid mesh paradigm was used to develop the HELIOS (Helicopter Overset Simulations) flow solver in order to allow for more flexible modeling of complex geometries [18]. HELIOS employs a set of two existing codes: a body-fitted unstructured mesh NSU3D flow solver to model the near-body area and a serial high-order ARC3D flow solver on structured Cartesian grids for the off-body area.…”