Wall-Modeling Strategies for Large-Eddy Simulation of Non-Equilibrium Turbulent Boundary Layers

Adler, Michael C.; González, David R.; Riley, Logan P.; Gaitonde, Datta V.

doi:10.2514/6.2020-1811

Cited by 6 publications

(3 citation statements)

References 41 publications

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“…Inversion of a composite profile including the viscous and buffer layers is more general for smooth wall applications, see e.g. Luchini (2018), Gonzalez, Adler & Gaitonde (2018) and Adler et al (2020). Algebraic EQWMs usually assume the velocity profile to be valid locally and instantaneously such that the LES velocity at the wall-model height may be used to find the local friction velocity and thus the local wall stress.…”

Section: Introductionmentioning

confidence: 99%

A Lagrangian relaxation towards equilibrium wall model for large eddy simulation

2022

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A large eddy simulation wall model is developed based on a formal interpretation of quasi-equilibrium that governs the momentum balance integrated in the wall-normal direction. The model substitutes the law-of-the-wall velocity profile for a smooth surface into the wall-normal integrated momentum balance, leading to a Lagrangian relaxation towards equilibrium (LaRTE) transport equation for the friction–velocity vector ${\boldsymbol u}_\tau (x,z,t)$ . This partial differential equation includes a relaxation time scale governing the rate at which the wall stress can respond to imposed fluctuations due to the inertia of the fluid layer from the wall to the wall-model height. A priori tests based on channel flow direct numerical simulation (DNS) data show that the identified relaxation time scale ensures self-consistency with assumed quasi-equilibrium conditions. The new approach enables us to formally distinguish quasi-equilibrium from additional, non-equilibrium contributions to the wall stress. A particular model for non-equilibrium contributions is derived, motivated by laminar Stokes layer dynamics in the viscous sublayer when applying fast-varying pressure gradients. The new wall modelling approach is first tested in standard equilibrium channel flow in order to document various properties of the approach. The model is then applied in large eddy simulation of channel flow with a suddenly applied spanwise pressure gradient (SSPG). The resulting mean wall-stress evolution is compared with DNS with good agreement. At the onset of the SSPG, the laminar Stokes layer develops rapidly while the LaRTE portion of the stress has a delayed response due to its inherent relaxation dynamics. Results also highlight open challenges such as modelling the response of near-wall turbulence occurring above the viscous sublayer and at time scales faster than quasi-equilibrium conditions.

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Section: Introductionmentioning

confidence: 99%

A Lagrangian relaxation towards equilibrium wall model for large eddy simulation

2022

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“…Firstly, the additive correction used to compute Re * ∆ requires some adjustment to smoothly merge to zero when Re τ ∆ < 11. We multiply the entire additive term by a factor that tends to zero when Re τ ∆ becomes smaller than O (10). The following expression yields good results:…”

Section: Effects Of (Mild) Pressure Gradientmentioning

confidence: 99%

“…If ∆ y falls in the viscous sublayer one must instead assume a linear profile [7], or one can use a smooth fit to the entire profile such as the classic fit by Reichardt (1951) [8] or the recent work in Refs. [9,10] including pressure gradient effects. Typically the fitted solution is for the velocity profile in inner units, which means that further iterative methods are needed to find the friction velocity.…”

Section: Introductionmentioning

confidence: 99%

A note on fitting a generalized Moody diagram for wall modeled Large Eddy Simulations

Meneveau

2020

Preprint

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Motivated by the needs of wall modeled Large Eddy Simulation (LES), we introduce fits to numerical solutions of the Reynolds Averaged Navier Stokes equations in their near-wall, boundary layer approximation including a mixing-length model. We provide practical fits that encompass a smooth transition between the viscous sublayer and inertial logarithmic layer, and include moderate pressure gradients as well as roughness effects. The proposed generalized fit function complies with analytical solutions valid in various asymptotic regimes and obviates the need for numerical iterative solution methods or numerical integration of ordinary differential equations during LES.

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An immersed boundary method for wall-modeled large-eddy simulation of turbulent high-Mach-number flows

Noordt

Ganju

Brehm

2022

Journal of Computational Physics

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Wall-Modeling Strategies for Large-Eddy Simulation of Non-Equilibrium Turbulent Boundary Layers

Cited by 6 publications

References 41 publications

A Lagrangian relaxation towards equilibrium wall model for large eddy simulation

A Lagrangian relaxation towards equilibrium wall model for large eddy simulation

A note on fitting a generalized Moody diagram for wall modeled Large Eddy Simulations

An immersed boundary method for wall-modeled large-eddy simulation of turbulent high-Mach-number flows

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