A p-adaptive Matrix-Free Discontinuous Galerkin Method for the Implicit LES of Incompressible Transitional Flows

Bassi, Francesco; Botti, Lorenzo Alessio; Colombo, Alessandro; Crivellini, Andrea; Franciolini, Matteo; Ghidoni, Antonio; Noventa, G.

doi:10.1007/s10494-020-00178-2

Cited by 21 publications

(14 citation statements)

References 61 publications

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“…The numerical dissipation introduced by the discretizaton itself, e.g., by numerical fluxes and the viscous stabilization, mainly acts at the smallest under-resolved scales and resembles a high frequency filter that mimics the role of a sub-grid-scale model. The ILES of several canonical and complex flows have been performed with the present code and can be found in [14,26].…”

Section: Discontinuous Galerkin Methodsmentioning

confidence: 99%

“…An efficient order-adaptive incompressible discontinuous Galerkin (DG) method [14] has been used in this work. The incompressible DG solver relies on a modified formulation for the inviscid interface numerical flux [27], computed as the exact solution of the Riemann problem relaxed by an artificial compressibility perturbation that guarantees the necessary coupling between the discrete incompressibility constraint and the rest of the governing equations.…”

Section: Discontinuous Galerkin Methodsmentioning

confidence: 99%

“…Both indicators aim at revealing a lack/excess of spatial accuracy in the numerical discretization and are here applied to the pressure variable. For a comprehensive discussion on the error estimator implementation see [14]. This strategy can be used in parallel only with a balanced repartitioning of the computational grid after each adaptation cycle, to overcome the natural imbalance of floating point operations per domain induced by the adaptation.…”

Section: P-adaptation Strategymentioning

confidence: 99%

“…On each level, except the coarsest, the smoothers use a cheap matrix-based preconditioner built by a simply neglecting the off-diagonal blocks of the restricted implicit operator. All the details of this preconditioning technique and its use in the order adaptive framework are presented in [14,26].…”

Section: P-adaptation Strategymentioning

confidence: 99%

“…In the present study an efficient order-adaptive discontinuous Galerkin (DG) method [14] for incompressible flows is used to perform the implicit LES [15] around the DrivAer fastback model. High-order DG finite elements methods proved to be very well suited [16][17][18][19][20][21][22][23][24][25] for ILES, where the unfiltered incompressible Navier-Stokes equations are solved, and the numerical dissipation introduced by the discretizaton itself, e.g., by numerical fluxes and the viscous stabilisation, plays the role of an explicit subgrid-scale (SGS) model that dissipates the smallest scale eddies.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of a Discontinuous Galerkin Method for the Simulation of the Turbulent Flow around the DrivAer Car Model

et al. 2021

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The turbulent flow over the DrivAer fastback model is here investigated with an order-adaptive discontinuous Galerkin (DG) method. The growing need of high-fidelity flow simulations for the accurate determination of problems, e.g., vehicle aerodynamics, promoted research on models and methods to improve the computational efficiency and to bring the practice of Scale Resolving Simulations (SRS), like the large-eddy simulation (LES), to an industrial level. An appealing choice for SRS is the Implicit LES (ILES) via a high-order DG method, where the favourable numerical dissipation of the space discretization scheme plays directly the role of a subgrid-scale model. Implicit time integration and the p-adaptive algorithm reduce the computational cost allowing a high-fidelity description of the physical phenomenon with very coarse mesh and moderate number of degrees of freedom. Two different models have been considered: (i) a simplified DrivAer fastback model, without the rear-view mirrors and the wheels, and a smooth underbody; (ii) the DrivAer fastback model, without rear-view mirrors and a smooth underbody. The predicted results have been compared with experimental data and CFD reference results, showing a good agreement.

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Section: Discontinuous Galerkin Methodsmentioning

confidence: 99%

Section: Discontinuous Galerkin Methodsmentioning

confidence: 99%

Section: P-adaptation Strategymentioning

confidence: 99%

Section: P-adaptation Strategymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Assessment of a Discontinuous Galerkin Method for the Simulation of the Turbulent Flow around the DrivAer Car Model

et al. 2021

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An implicit p‐adaptive discontinuous Galerkin solver for CAA/CFD simulations

Colombo

Crivellini

Ghidoni

et al. 2022

Numerical Methods in Fluids

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In the last decades flow simulations have become a routine practice in many industrial fields for the aerodynamic and noise prediction. Moreover, the ever increasing interest in simulating off‐design operating conditions promoted the development of high‐fidelity simulation tools to overcome the modeling and accuracy limits of standard industrial codes in predicting turbulent separated flows. The discontinuous Galerkin (DG) method is well suited for this class of simulations, but today DG‐based CFD and CAA (Computational AeroAcoustics) solvers cannot yet reach the computational efficiency of well‐established commercial codes. As a consequence, the present paper aims at exploiting some attractive strategies, such as the adaptation of the elemental polynomial degree (p‐adaptation) and of the degree of exactness of quadrature rules, to enhance the computational efficiency of an implicit DG platform for CFD and CAA simulations. Moreover, a sponge layer non‐reflecting boundary treatment has been also implemented for CAA. The predicting capabilities of the method have been assessed on classical CAA and CFD test cases. The proposed adaptive strategy guarantees a significant reduction ( prefix≈-.27em50%) of the computational effort for both CFD and CAA simulations, compared to uniform‐order discretizations, while not spoiling the high accuracy requested to an high‐fidelity simulation tool.

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High-Performance Implementation of Discontinuous Galerkin Methods with Application in Fluid Flow

Kronbichler

2021

CISM International Centre for Mechanical Sciences

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A p-adaptive Matrix-Free Discontinuous Galerkin Method for the Implicit LES of Incompressible Transitional Flows

Cited by 21 publications

References 61 publications

Assessment of a Discontinuous Galerkin Method for the Simulation of the Turbulent Flow around the DrivAer Car Model

Assessment of a Discontinuous Galerkin Method for the Simulation of the Turbulent Flow around the DrivAer Car Model

An implicit p‐adaptive discontinuous Galerkin solver for CAA/CFD simulations

High-Performance Implementation of Discontinuous Galerkin Methods with Application in Fluid Flow

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