Large eddy simulation with modeled wall-stress: recent progress and future directions

Larsson, Johan; Kawai, Soshi; Bodart, Julien; Bermejo-Moreno, Iván

doi:10.1299/mer.15-00418

Cited by 364 publications

(244 citation statements)

References 80 publications

(112 reference statements)

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“…The top boundary condition is a zero-gradient condition. The integral wall model (iWMLES) [47,54] is used for prescribing the wall stress in these high-Reynolds-number LES where the viscous sublayer is unresolved (see [55,56] for reviews of wall models in LES). The iWMLES approach enables one to capture non-equilibrium effects (such as pressure gradients) at a cost that scales similarly to the equilibrium wall model.…”

Section: Large-eddy Simulations (A) Roughness With Finite Hierarchiesmentioning

confidence: 99%

Modelling turbulent boundary layer flow over fractal-like multiscale terrain using large-eddy simulations and analytical tools

Yang

Meneveau

2017

Phil. Trans. R. Soc. A.

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In recent years, there has been growing interest in large-eddy simulation (LES) modelling of atmospheric boundary layers interacting with arrays of wind turbines on complex terrain. However, such terrain typically contains geometric features and roughness elements reaching down to small scales that typically cannot be resolved numerically. Thus subgrid-scale models for the unresolved features of the bottom roughness are needed for LES. Such knowledge is also required to model the effects of the ground surface ‘underneath’ a wind farm. Here we adapt a dynamic approach to determine subgrid-scale roughness parametrizations and apply it for the case of rough surfaces composed of cuboidal elements with broad size distributions, containing many scales. We first investigate the flow response to ground roughness of a few scales. LES with the dynamic roughness model which accounts for the drag of unresolved roughness is shown to provide resolution-independent results for the mean velocity distribution. Moreover, we develop an analytical roughness model that accounts for the sheltering effects of large-scale on small-scale roughness elements. Taking into account the shading effect, constraints from fundamental conservation laws, and assumptions of geometric self-similarity, the analytical roughness model is shown to provide analytical predictions that agree well with roughness parameters determined from LES. This article is part of the themed issue ‘Wind energy in complex terrains’.

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Section: Large-eddy Simulations (A) Roughness With Finite Hierarchiesmentioning

confidence: 99%

Modelling turbulent boundary layer flow over fractal-like multiscale terrain using large-eddy simulations and analytical tools

Yang

Meneveau

2017

Phil. Trans. R. Soc. A.

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“…An alternative method proposed here involves following the approach commonly used for wall modeling in finite differences . In this approach, the grid extends all the way to the solid wall (Figure B) and we are, in fact, imposing the wall shear stress at y =0, in terms of the velocity evaluated at y = d , where d now denotes the distance between the first grid point (B), which now coincides with the wall, and the first grid point off the wall (C).…”

Section: Wall Modelingmentioning

confidence: 99%

“…An alternative method proposed here involves following the approach commonly used for wall modeling in finite differences. [1][2][3][4][5] In this approach, the grid extends all the way to the solid wall ( Figure 1B) and we are, in fact, imposing the wall shear stress at y = 0, in terms of the velocity evaluated at y = d, where d now denotes the distance between the first grid point (B), which now coincides with the wall, and the first grid point off the wall (C). Due to the fact that this velocity has a nonzero vertical component, the problem outlined in the previous paragraph in regards to the resolved stress being zero at a distance y = d from the wall is solved.…”

Section: Classical Finite Difference Approachmentioning

confidence: 99%

“…where the last approximation stems from integrating the Navier-Stokes equations in the near-wall elements. As opposed to the classical FE approach, this method is equivalent to a wall-stress model (again following the classification of Larsson et al 4 ), where a wall model is solved over a layer of thickness d.…”

Section: Classical Finite Difference Approachmentioning

confidence: 99%

“…They can be categorized into two groups, those that directly model the wall stress and those that employ a Reynolds-averaged Navier-Stokes (RANS) approach in the inner layer. The reader can refer (A) Finite element (B) Proposed approach FIGURE 1 Wall-modeling approach in different spatial discretization methods to other works [1][2][3][4][5] for additional information on the wall models. In this work, we focus on the implementation of wall modeling for LES in a finite element (FE) framework.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Wall‐modeled large‐eddy simulation in a finite element framework

Owen

Chrysokentis

Ávila

et al. 2019

Numerical Methods in Fluids

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Summary This work studies the implementation of wall modeling for large‐eddy simulation in a finite element context. It provides a detailed description of how the approach used by the finite volume and finite differences communities is adapted to the finite element context. The new implementation is as simple and easy to implement as the classical finite element one, but it provides vastly superior results. In the typical approach used in finite elements, the mesh does not extend all the way to the wall, and the wall stress is evaluated at the first grid point, based on the velocity at the same point. Instead, we adopt the approach commonly used in finite differences, where the mesh covers the whole domain and the wall stress is obtained at the wall grid point, with the velocity evaluated at the first grid point off the wall. The method is tested in a turbulent channel flow at Reτ=2003, a neutral atmospheric boundary layer flow, and a flow over a wall‐mounted hump, with significant improvement in the results compared to the standard finite element approach. Additionally, we examine the effect of evaluating the input velocity further away from the wall, as well as applying temporal filtering on the wall‐model input.

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A multiscale approach to hybrid RANS/LES wall modeling within a high‐order discontinuous Galerkin scheme using function enrichment

Krank

Kronbichler

Wall

2019

Numerical Methods in Fluids

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Summary We present a novel approach to hybrid Reynolds‐averaged Navier‐Stokes (RANS)/ large eddy simulation (LES) wall modeling based on function enrichment, which overcomes the common problem of the RANS‐LES transition and enables coarse meshes near the boundary. While the concept of function enrichment as an efficient discretization technique for turbulent boundary layers has been proposed in an earlier article by Krank & Wall (A new approach to wall modeling in LES of incompressible flow via function enrichment. J Comput Phys. 2016;316:94‐116), the contribution of this work is a rigorous derivation of a new multiscale turbulence modeling approach and a corresponding discontinuous Galerkin discretization scheme. In the near‐wall area, the Navier‐Stokes equations are explicitly solved for an LES and a RANS component in one single equation. This is done by providing the Galerkin method with an independent set of shape functions for each of these two methods; the standard high‐order polynomial basis resolves turbulent eddies, where the mesh is sufficiently fine and the enrichment automatically computes the ensemble‐averaged flow if the LES mesh is too coarse. As a result of the derivation, the RANS model is applied solely to the RANS degrees of freedom, which effectively prevents the typical issue of a log‐layer mismatch in attached boundary layers. As the full Navier‐Stokes equations are solved in the boundary layer, spatial refinement gradually yields wall‐resolved LES with exact boundary conditions. Numerical tests show the outstanding characteristics of the wall model regarding grid independence, superiority compared to equilibrium wall models in separated flows, and achieve a speed‐up by two orders of magnitude compared to wall‐resolved LES.

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Large eddy simulation with modeled wall-stress: recent progress and future directions

Cited by 364 publications

References 80 publications

Modelling turbulent boundary layer flow over fractal-like multiscale terrain using large-eddy simulations and analytical tools

Modelling turbulent boundary layer flow over fractal-like multiscale terrain using large-eddy simulations and analytical tools

Wall‐modeled large‐eddy simulation in a finite element framework

A multiscale approach to hybrid RANS/LES wall modeling within a high‐order discontinuous Galerkin scheme using function enrichment

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