Mesh adaptation for large‐eddy simulations in complex geometries

Bénard, Pierre; Balarac, Guillaume; Moureau, Vincent; Dobrzynski, Cécile; Lartigue, Ghislain; D'Angelo, Yves

doi:10.1002/fld.4204

Cited by 80 publications

(50 citation statements)

References 52 publications

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“…with no summation over n. Therefore, the divergence of this term has a second derivative in its leading term and somewhat resembles the truncation or interpolation error of a low-order numerical scheme [cf. 13,19,35,36]. Note that depending on the test-filter (i.e., first, second or higher derivatives in the definition of the differential filter) the Leonard-like stress can generally resemble the truncation error of different numerical schemes.…”

Section: Defining the Difference Between The Two Solutions Asmentioning

confidence: 99%

“…The difference between grids the G-k and G-k is quantified by the error in the refinement regions, E R , defined in Eqn. 19. In this section, R ref is taken from grid G-k and the integration domain is limited to Ω : x = (x, y) ∈ [−20H, 25H]× [−H, 0.5H] to eliminate the effect of coarser streamwise resolution of grids G-k further away from the wall.…”

Section: Gridmentioning

confidence: 99%

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Towards systematic grid selection in LES: Identifying the optimal spatial resolution by minimizing the solution sensitivity

Toosi

Larsson

2020

Computers & Fluids

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The accuracy of a large eddy simulation (LES) is determined by the accuracy of the model used to describe the effect of unresolved scales, the numerical errors of the resolved scales, and the optimality of the length scale that separates resolved from unresolved scales (the filter-width, or the coarse-graining length scale). This paper is focused entirely on the last of these, proposing a systematic algorithm for identifying the "optimal" spatial distribution of the coarse-graining length scale and its aspect ratio. The core idea is that the "optimal" coarse-graining length scale for LES is the largest length scale for which the LES solution is minimally sensitive to it. This idea is formulated based on an error indicator that measures the sensitivity of the solution and a criterion that determines how that error indicator should vary in space and direction to minimize the overall sensitivity of the solution. The solution to this optimization problem is that the cell-integrated error indicator should be equi-distributed; a corollary is that one cannot link the accuracy in LES to quantities that are not cell-integrated, including the common belief that LES is accurate whenever 80-90% of the energy is resolved. The full method is tested on the wall-resolved LES of turbulent channel flow and the flow over a backward-facing step, with final length scale fields (or filter-width fields, or grids) that are close to what is considered "best practice" in the LES literature. Finally, the derivation of the error indicator offers an alternative explanation for the success of the dynamic procedure.

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Section: Defining the Difference Between The Two Solutions Asmentioning

confidence: 99%

Section: Gridmentioning

confidence: 99%

Towards systematic grid selection in LES: Identifying the optimal spatial resolution by minimizing the solution sensitivity

Toosi

Larsson

2020

Computers & Fluids

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“…Physical and chemical processes occurring in the combustion chamber are rapid and complete processes of oxidation of the fuel (in this case highash content coal) take place at high temperatures, accompanied by a large release of energy due to chemical reactions and changes in the concentrations of all substances interact. To describe real physical transformations that occur during combustion of fuel, it is necessary to choose an adequate numerical model [21][22][23][24] of physical process. Chemical reactions, which in turn determines the source terms in the equations for energy and the substance components.…”

Section: Methodsmentioning

confidence: 99%

Heat and mass transfer processes at high-temperature media during combustion of low-grade pulverized coal

Аскарова

Bolegenova

Šafařík

et al. 2018

Int. j. math. phys.

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The article is devoted to the complex research processes of heat and mass transfer occurring in the real conditions of solid fuel (coal) combustion. Development of technological processes with economic and ecological advantages are the main purpose for many researches in thermal physics and technical physics. The complex processes of heat and mass transfer in the presence of combustion are non-stationary, strongly non-isothermal with a constant change in the physical and chemical state of the environment. It greatly complicates their experimental study. In this case, studying of heat and mass transfer in high-reacting media with simulation of physical and chemical processes occur during combustion of pulverized coal is important for the solution of modern power engineering industry and ecology problems. In this regard, a comprehensive study of heat and mass transfer processes at hightemperature media observed. Investigations based on the achievements of modern physics by using numerical methods for 3D modeling. Numerical experiments are conducted to describe and study aerodynamic characteristics, heat and mass transfer processes during the burning of pulverized Kazakhstan low-grade coal. The results obtained are of great practical importance, since they allow us to develop recommendations for the improvement and design of new combustion chambers and burners, and also can be useful in optimizing the whole process of burning fossil fuels.

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“…This can be done either as a dynamic approach, i.e. performed at run time, so that the mesh is adapted to the instantaneous solution (see [24][25][26]), but can also be done statically, i.e. performed using mean flow characteristics once or twice during the whole simulation [11], as proposed here.…”

Section: Mesh Metric For the Prediction Of Pressure Lossesmentioning

confidence: 99%

A Mesh Adaptation Strategy to Predict Pressure Losses in LES of Swirled Flows

Daviller

Brebion

Xavier

et al. 2017

Flow Turbulence Combust

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Large-Eddy Simulation (LES) has become a potent tool to investigate instabilities in swirl flows even for complex, industrial geometries. However, the accurate prediction of pressure losses on these complex flows remains difficult. The paper identifies localised near-wall resolution issues as an important factor to improve accuracy and proposes a solution with an adaptive mesh h-refinement strategy relying on the tetrahedral fully automatic MMG3D library of Dapogny et al. (J. Comput. Phys. 262, 358-378, 2014) using a novel sensor based on the dissipation of kinetic energy. Using a joint experimental and numerical LES study, the methodology is first validated on a simple diaphragm flow before to be applied on a swirler with two counter-rotating passages. The results demonstrate that the new sensor and adaptation approach can effectively produce the desired local mesh refinement to match the target losses, measured experimentally. Results shows that the accuracy of pressure losses prediction is mainly controlled by the mesh quality and density in the swirler passages. The refinement also improves the computed velocity and turbulence profiles at the swirler outlet, compared to PIV results. The significant improvement of results confirms that the sensor is able to identify the relevant physics of turbulent flows that is essential for the overall accuracy of LES. Finally, in the appendix, an additional comparison of the sensor fields on tetrahedral and hexahedral meshes demonstrates that the methodology is broadly applicable to all mesh types.

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Mesh adaptation for large‐eddy simulations in complex geometries

Cited by 80 publications

References 52 publications

Towards systematic grid selection in LES: Identifying the optimal spatial resolution by minimizing the solution sensitivity

Towards systematic grid selection in LES: Identifying the optimal spatial resolution by minimizing the solution sensitivity

Heat and mass transfer processes at high-temperature media during combustion of low-grade pulverized coal

A Mesh Adaptation Strategy to Predict Pressure Losses in LES of Swirled Flows

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