Turbulence intensities in large-eddy simulation of wall-bounded flows

Bae, H. Jane; Lozano-Durán, Adrián; Bose, Sanjeeb; Moin, Parviz

doi:10.1103/physrevfluids.3.014610

Cited by 77 publications

(55 citation statements)

References 39 publications

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“…Because, for the simulations with [u τ ] = 0, the spanwise and wall-normal rms velocity fluctuations are found to be lower than the reference DNS, while the streamwise velocity fluctuations are over-predicted except for sufficiently fine ∆x + -∆z + resolutions. This trend for velocity fluctuations is not uniquely observed for the resolutions associated to [u τ ] = 0 and may be the case for other resolutions as well, as discussed in Section IV C and also in other studies, see [2,4,18] and the references therein.…”

Section: B Convergence Of Friction Velocitymentioning

confidence: 66%

“…The existence of such loci can be left totally to the artefacts due to the numerical method and cancellation of the errors. However, providing a clear-cut explanation on why the particular pattern for the [u τ ] = 0 curve is observed in Figure 2 is not an easy task, considering the complexity of deriving modified equation and truncation errors corresponding to the discretized form of equations (2).…”

Section: B Convergence Of Friction Velocitymentioning

confidence: 99%

“…It is expected that as the LES grid is refined, the uncaptured portion of the energy due to the unresolved scales reduces and eventually completely goes away. However, over-prediction of TKE due to under-resolving the near-wall region is a known issue in the numerical simulation of wall-bounded turbulent flows, for instance see the discussions in [2,4,18,26], and the references therein.…”

Section: Errors In Cross-channel Profilesmentioning

confidence: 99%

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Effect of grid resolution on large eddy simulation of wall-bounded turbulence

Rezaeiravesh

Liefvendahl

2018

Physics of Fluids

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The effect of grid resolution on large eddy simulation (LES) of wall-bounded turbulent flow is investigated. A channel flow simulation campaign involving systematic variation of the streamwise (∆x) and spanwise (∆z) grid resolution is used for this purpose. The main friction-velocity based Reynolds number investigated is 300. Near the walls, the grid cell size is determined by the frictional scaling, ∆x + and ∆z + , and strongly anisotropic cells, with first ∆y + ∼ 1, thus aiming for wallresolving LES. Results are compared to direct numerical simulations (DNS) and several quality measures are investigated, including the error in the predicted mean friction velocity and the error in cross-channel profiles of flow statistics. To reduce the total number of channel flow simulations, techniques from the framework of uncertainty quantification (UQ) are employed. In particular, generalized polynomial chaos expansion (gPCE) is used to create meta models for the errors over the allowed parameter ranges. The differing behavior of the different quality measures is demonstrated and analyzed. It is shown that friction velocity, and profiles of velocity and the Reynolds stress tensor, are most sensitive to ∆z + , while the error in the turbulent kinetic energy is mostly influenced by ∆x + . Recommendations for grid resolution requirements are given, together with quantification of the resulting predictive accuracy. The sensitivity of the results to subgrid-scale (SGS) model and varying Reynolds number is also investigated. All simulations are carried out with second-order accurate finite-volume based solver OpenFOAM. It is shown, the choice of numerical scheme for the convective term significantly influences the error portraits. It is emphasized that the proposed methodology, involving gPCE, can be applied to other modeling approaches, i.e. other numerical methods and choice of SGS model.

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Section: B Convergence Of Friction Velocitymentioning

confidence: 66%

Section: B Convergence Of Friction Velocitymentioning

confidence: 99%

Section: Errors In Cross-channel Profilesmentioning

confidence: 99%

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Effect of grid resolution on large eddy simulation of wall-bounded turbulence

Rezaeiravesh

Liefvendahl

2018

Physics of Fluids

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“…The consequence is that even if the mean velocity profile matches that of DNS for an optimal (l 1 , l 2 ), some pairs are preferred in order to avoid the near-wall under-and over-shoot in the rms velocity fluctuations. A more comprehensive study of the near-wall turbulent intensities with the slip boundary condition can be found in Bae et al (2018). Figure 5(b) stresses another important property of the slip condition.…”

Section: Turbulence Intensities and Reynolds Stress Contributionmentioning

confidence: 99%

Dynamic slip wall model for large-eddy simulation

et al. 2018

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Wall modelling in large-eddy simulation (LES) is necessary to overcome the prohibitive near-wall resolution requirements in high-Reynolds-number turbulent flows. Most existing wall models rely on assumptions about the state of the boundary layer and require a priori prescription of tunable coefficients. They also impose the predicted wall stress by replacing the no-slip boundary condition at the wall with a Neumann boundary condition in the wall-parallel directions while maintaining the no-transpiration condition in the wall-normal direction. In the present study, we first motivate and analyse the Robin (slip) boundary condition with transpiration (nonzero wall-normal velocity) in the context of wall-modelled LES. The effect of the slip boundary condition on the one-point statistics of the flow is investigated in LES of turbulent channel flow and flat-plate turbulent boundary layer. It is shown that the slip condition provides a framework to compensate for the deficit or excess of mean momentum at the wall. Moreover, the resulting nonzero stress at the wall alleviates the well-known problem of the wall-stress under-estimation by current subgrid-scale (SGS) models . Secondly, we discuss the requirements for the slip condition to be used in conjunction with wall models and derive the equation that connects the slip boundary condition with the stress at the wall. Finally, a dynamic procedure for the slip coefficients is formulated, providing a dynamic slip wall model free of a priori specified coefficients. The performance of the proposed dynamic wall model is tested in a series of LES of turbulent channel flow at varying Reynolds numbers, non-equilibrium three-dimensional transient channel flow, and zeropressure-gradient flat-plate turbulent boundary layer. The results show that the dynamic wall model is able to accurately predict one-point turbulence statistics for various flow configurations, Reynolds numbers, and grid resolutions. †

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“…The virtual origins below the simulation boundary are modelled by means of off-wall conditions for the three velocities, which have previously been used to model the presence of smooth walls below the simulation boundary [20,21,22]. Although traditionally Robin boundary conditions have been used to impose the tangential virtual origins in terms of slip lengths [14,13], the origin for the wall-normal velocity has not been introduced in that framework.…”

Section: Numerical Setupmentioning

confidence: 99%

Manipulation of near-wall turbulence by surface slip and permeability

Gomez-de-Segura

Fairhall

MacDonald

et al. 2018

J. Phys.: Conf. Ser.

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Abstract. We study the effect on near-wall turbulence of tangential slip and wall-normal transpiration, typically produced by textured surfaces and other surface manipulations. For this, we conduct direct numerical simulations (DNSs) with different virtual origins for the different velocity components. The different origins result in a relative wall-normal displacement of the near-wall, quasi-streamwise vortices with respect to the mean flow, which in turn produces a change in drag. The objective of this work is to extend the existing understanding on how these virtual origins affect the flow. In the literature, the virtual origins for the tangential velocities are typically characterised by slip boundary conditions, while the wall-normal velocity is assumed to be zero at the boundary plane. Here we explore different techniques to define and implement the three virtual origins, with special emphasis on the wall-normal one. We investigate impedance conditions relating the wall-normal velocity to the pressure, and linear relations between the velocity components and their wall-normal gradients, as is typically done to impose slip conditions. These models are first tested to represent a smooth wall below the boundary plane, with all virtual origins equal, and later for different tangential and wall-normal origins. Our results confirm that the change in drag is determined by the offset between the origins perceived by mean flow and the quasi-streamwise vortices or, more generally, the nearwall turbulent cycle. The origin for the latter, however, is not set by the spanwise virtual origin alone, as previously proposed, but by a combination of the spanwise and wall-normal origins, and mainly determined by the shallowest of the two. These observations allow us to extend the existing expression to predict the change in drag, accounting for the wall-normal effect when the transpiration is not negligible.

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Turbulence intensities in large-eddy simulation of wall-bounded flows

Cited by 77 publications

References 39 publications

Effect of grid resolution on large eddy simulation of wall-bounded turbulence

Effect of grid resolution on large eddy simulation of wall-bounded turbulence

Dynamic slip wall model for large-eddy simulation

Manipulation of near-wall turbulence by surface slip and permeability

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