Parallel anisotropic mesh refinement with dynamic load balancing for transonic flow simulations

Abstract

Abstract. The present paper discusses an effective adaptive methods suited for use in parallel environment. An in-house, parallel flow solver based on the residual distribution method is used for the solution of flow problems. Simulation is parallelized based on the domain decomposition approach. Adaptive changes to the mesh are achieved by two distinctive techniques. Mesh refinement is performed by dividing element edges and a subsequent application of pre defined splitting templates. Mesh regularization and derefinement is achieved through topology conserving node movement (r-adaptivity). Parallel implementations of an adaptive use the dynamic load balancing technique.Key words: parallel CFD, adaptation, dynamic load balancing, mesh refinement, parallel efficiency.Parallel anisotropic mesh refinement with dynamic load balancing for transonic flow simulations [28][29][30][31][32]. In general, this approach yields high quality meshes for arbitrarily complex geometries [4,[33][34][35][36]. Nevertheless this approach is difficult to implement in parallel simulations because of the global nature of the remeshing operation.An alternative approach is to apply modifications to the computational mesh only in the regions of interest. Either by local mesh modification operators (edge splits, edge collapses and edge swaps) [37][38][39][40] or element bisection (e.g., based on template refinement) [10,[41][42][43][44][45][46][47]. Locality of these methods makes them especially attractive for application in parallel computing, as the necessary communication volume and frequency become limited, boosting parallel performance.Another possibility is brought by the r-adaptive methods, in which grid nodes are allowed to move without changing the topology of the mesh. This technique is used either to augment local refinement methods [48,49], or as an adaptive tool in itself [50][51][52]. Application of r-adaptive algorithms might be beneficial in parallel computations, as neither the grid topology nor the load balance become affected.Although adaptive methods are well recognised in the academic community, the broader application of adaptation for industrial problems has been limited. This paper presents an approach towards fully parallel and automatic mesh adaptation method that can be used for 3D industrial cases. The h-r adaptive method is developed, suitable for parallel simulation of transonic flows. Adaptivity is accomplished by anisotropic template-based element bisection method. The coarsening step is carried out via an elastic analogy node movement. Anisotropic mesh modifications are driven by a Hessian based approach.

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…Specifically, the CFD technique was used for a computer calculation with the finite volume method (FVM) [15], employing the software Ansys Fluent [16]. At present, CFD is commonly used in engineering fields related to fluids [17][18][19]. The simulation was intended for determining the air flow to the forge and the pressure carried.…”

“…Considering the boundary of the body divided into two parts (S = S u [ S t ), the boundary conditions are: uj S u = u 0 tj S t = t 0 (18) whereu 0 andt 0 are the admissible displacements and loads, respectively.…”

Bulletin of the Polish Academy of Sciences: Technical Sciences

“…Last years extensive experimental, theoretical and numerical efforts have been done to understand important issues of fluid dynamics [1][2][3]. There is no commonly accepted theory developed for recognition of fundamental qualitative properties of the flow (turbulent -laminar, steady -unsteady, mixing -non-mixing), while in many practical applications there is a great need to find effective methods to assess these properties [4][5][6].…”