An unstructured adaptive mesh refinement approach for computational fluid dynamics of reacting flows

• Published in: Journal of computational physics Vol. 468; p. 111480
• Main Authors: Cant, R.S., Ahmed, U., Fang, J., Chakarborty, N., Nivarti, G., Moulinec, C., Emerson, D.R.
• Format: Journal Article
• Language: English
• Published: Cambridge Elsevier Inc 01.11.2022; Elsevier Science Ltd
• Subjects: Adaptive control; Adaptive mesh refinement; Algorithms; Boundary layers; Cartesian coordinates; Cell division; Channel flow; Compressibility; Computational fluid dynamics; Computational physics; Computer simulation; Data structures; Direct numerical simulation; Direct numerical simulations; Domain decomposition methods; Domain names; Finite element method; Flame propagation; Fluid flow; Grid refinement (mathematics); Laminar flow; Morton code; Polynomial flux reconstruction; Polynomials; Premixed flames; Reacting flow; Reacting flows; Runge-Kutta method; Runge-Kutta scheme; Three dimensional flow; Turbulence; Turbulent flames; Adaptive mesh refinement; Reacting flows; Runge-Kutta scheme; Direct numerical simulations; Morton code; Polynomial flux reconstruction
• ISSN: 0021-9991; 1090-2716
• DOI: 10.1016/j.jcp.2022.111480

A new Direct Numerical Simulation (DNS) code HAMISH with Adaptive Mesh Refinement (AMR) has been developed to simulate compressible reacting flow in a computationally economical manner. The focus is on problems where high gradients of temperature, density and species mass fraction remain localised, for example within the interior structure of flames. The resolution requirements of such local high-gradient regions often determine the global mesh spacing when uniform meshes are used. The numerical framework in HAMISH is based on an unstructured finite-volume approach together with a Runge-Kutta algorithm for time-stepping. The unstructured Cartesian mesh used in HAMISH allows for adaptive refinement and de-refinement of the local mesh depending on the demands of the flow physics and numerical accuracy. The code utilises an octree data structure and a Morton space-filling curve, allowing efficient cell division as well as straightforward parallel domain decomposition. The spatial discretisation scheme uses fourth-order polynomial reconstruction to evaluate the inter-cell fluxes. A third-order three-step explicit Runge-Kutta time-marching algorithm is used together with adaptive time-stepping with proportional-integral-type error control using an embedded Runge-Kutta scheme. The code is fully parallelised through domain decomposition over an arbitrary number of processors and exhibits a high level of parallel efficiency. In this paper the key capabilities of HAMISH are demonstrated based on a number of test cases. These test cases include (a) simulation of 1-D planar laminar premixed flames to demonstrate the capability of AMR in capturing the sharp gradients within the flame; (b) fully developed laminar channel flow, which shows that the code is capable of refining the mesh in the boundary layer next to the wall; (c) 2-D expanding flame under quiescent laminar condition, which demonstrates that the code is capable of dynamic local mesh refinement based on the position of the flame front; (d) 3-D non-reacting Taylor-Green vortex which demonstrates HAMISH can deal with vortical motion typical of turbulent flows; (e) 3-D premixed turbulent flame propagation under isotropic homogeneous decaying turbulence to demonstrate that the code can be employed for production level DNS of turbulent reacting flows. •High-order Adaptive Mesh Refinement approach for turbulent combustion simulation.•Octree data structure with Morton code indexing.•Efficient mesh refinement and derefinement with automatic parallel load-balancing.•Demonstration of capability on several laminar and turbulent flow and combustion test cases.