An automatic hybrid numerical scheme for global RANS-LES approaches

Guseva, Ekaterina; Garbaruk, A. V.; Strelets, M. Kh.

doi:10.1088/1742-6596/929/1/012099

Cited by 19 publications

(6 citation statements)

References 6 publications

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“…At the inlet boundary, unsteady disturbances were superimposed on the profiles of the flow parameters according to the method [46], which quickly switched the simulation to the scale-resolving mode. In contrast to RANS simulations, spatial approximation of the convective fluxes was done using the hybrid scheme, which blends the upwind WENO5 approximation in the RANS sublayer and the 2-nd order central differences in the LES region using the formula proposed in [47]. The time step was equal to 0.01t char , where t char = H/U ∞ is the characteristic time of the flow.…”

Section: Setup Of the Hybrid Simulations And The Resultsmentioning

confidence: 99%

Calibration of a Near-Wall Differential Reynolds Stress Model Using the Updated Direct Numerical Simulation Data and Its Assessment

Usov,

Troshin,

Anisimov

et al. 2023

Energies

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In the article, a differential Reynolds stress model is recalibrated using turbulent channel flow direct numerical simulation data in the range of friction Reynolds numbers 550–5200. The calibration aims to produce a RANS sublayer model for use within the hybrid RANS/LES framework. The model is designed to capture the average field of a thin near-wall part of a boundary layer as accurately as possible. An a posteriori procedure is employed in which one-dimensional channel flow calculations are performed for all variations of the model coefficients at each stage of the optimization procedure. The coefficients are initialized with their original values and then optimized by minimizing the appropriately chosen norm. An improved representation of the mean velocity profile and peak Reynolds stress values is demonstrated. Both models—baseline and recalibrated—are implemented in an in-house CFD code, and several simulations, including a channel flow, a flat plate boundary layer and a boundary layer separation from a rounded step, are performed. The latter benchmark flow is also simulated in hybrid RANS/LES mode. The updated model is compared to the original one, demonstrating improvements over the baseline model in the cases it was designed for.

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Section: Setup Of the Hybrid Simulations And The Resultsmentioning

confidence: 99%

Calibration of a Near-Wall Differential Reynolds Stress Model Using the Updated Direct Numerical Simulation Data and Its Assessment

Usov,

Troshin,

Anisimov

et al. 2023

Energies

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“…It is based on a higher-accuracy scheme with an extended numerical stencil, namely, the EBR (Edge-Based Reconstruction) scheme [8] with an edge-based quasi-1D reconstruction of variables. The hybrid scheme for convective terms uses the adapting blend of the central-difference and upwind schemes [9] based on an extended numerical stencil containing four points with the special hybridizing function [36]. The values of the sensor function ( [33] in OpenFOAM and [36] in NOISEtte), which controls the amount of diffusion (𝜎 upw ) in the hybrid schemes, are limited both from below and from above, similarly to [9].…”

Section: Mathematical Models and Numerical Methodsmentioning

confidence: 99%

“…The hybrid scheme for convective terms uses the adapting blend of the central-difference and upwind schemes [9] based on an extended numerical stencil containing four points with the special hybridizing function [36]. The values of the sensor function ( [33] in OpenFOAM and [36] in NOISEtte), which controls the amount of diffusion (𝜎 upw ) in the hybrid schemes, are limited both from below and from above, similarly to [9]. The formulation of the Δ𝜔 and Δ 𝜔 subgrid length scales in the framework of the NOISEtte edge-based algorithm is given in Appendix A.…”

Section: Mathematical Models and Numerical Methodsmentioning

confidence: 99%

Evaluation of Enhanced Gray Area Mitigation Approaches Based on Jet Aeroacoustics

et al. 2023

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An investigation of various eddy viscosity models for accurate scale-resolving simulation of aerodynamics and aeroacoustics of a turbulent jet is presented. The models are considered from the perspective of solving the so-called gray area problem. This problem is related to nonphysical delay in the transition from Reynolds-averaged Navier–Stokes (RANS) to large-eddy simulation (LES) in hybrid RANS–LES approaches such as detached eddy simulation (DES) when applied to shear-layer flows. The performance of recently developed dynamic adapting subgrid length scales ([Formula: see text], [Formula: see text], and [Formula: see text]) and subgrid LES models ([Formula: see text] and S3QR) separately and together is demonstrated. The object of the investigation is an immersed subsonic turbulent jet. The simulations are carried out on a set of refining meshes using two different scale-resolving numerical algorithms with basic and higher-accuracy schemes on unstructured meshes. The evaluation of various eddy-viscosity models within the DES approach is mostly focused on the analysis of far-field noise. The study has clearly demonstrated the importance of both a numerical scheme and a subgrid turbulence model. The results show that some of the considered techniques provide the necessary accuracy to predict the noise generated by a turbulent jet. The features of the considered approaches are identified and discussed. Recommendations are formulated for the choice of the LES model and subgrid length scale for this kind of problem.

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“…The blending function, σ, is taken from [23]. CD-4 and CD-6 are implemented as half-sums of the WENO3 and WENO5 reconstructions (with optimal weights), respectively, on the left and right sides of the cell's face.…”

Section: Numerical Methods and Modelmentioning

confidence: 99%

“…The inertial interval was as wide as it would have been in the case of a pure central-difference approximation (solid curve, Figure 8), although a slight upward convexity could be seen upon closer consideration. Despite this remark, the hybrid scheme is of the most interest for practical Indeed, in the presence of RANS regions and non-turbulent regions far from the domain of study, switching to the upwind scheme is a necessary condition for stable simulation [23].…”

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confidence: 99%

A Method for Choosing the Spatial and Temporal Approximations for the LES Approach

Бахнэ

Sabelnikov

2022

Fluids

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Analysis and optimization of the hybrid upwind-central numerical methods for modern versions of large eddy simulations (LESs) are presented herein. Optimization was performed based on examination of the characteristics of the spatial and temporal finite-volume approximations of the convective terms of filtered Navier–Stokes equations. A method for selecting level of subgrid viscosity that corresponds to the chosen numerical scheme and makes it possible to obtain an extended inertial interval of the energy spectrum is proposed. A series of LESs of homogeneous isotropic turbulence decay were carried out, and the optimal values of the subgrid model constants included in the hybrid shear stress transport delay detached eddy simulation (SST-DDES) method were determined. A procedure for generating a consistent initial field of subgrid parameters for these simulations is described. The three-stage explicit Runge–Kutta method was demonstrated to be sufficient for stable time integration, while the popular explicit midpoint method was not. The slope of the energy spectrum was shown to be almost independent of the central-difference scheme order and of the mesh spacing when the correct numerical method was applied. Numerical viscosity was found to become much greater than subgrid viscosity when the upwind scheme contributed about 10% or more to the convective flux approximation.

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An automatic hybrid numerical scheme for global RANS-LES approaches

Cited by 19 publications

References 6 publications

Calibration of a Near-Wall Differential Reynolds Stress Model Using the Updated Direct Numerical Simulation Data and Its Assessment

Calibration of a Near-Wall Differential Reynolds Stress Model Using the Updated Direct Numerical Simulation Data and Its Assessment

Evaluation of Enhanced Gray Area Mitigation Approaches Based on Jet Aeroacoustics

A Method for Choosing the Spatial and Temporal Approximations for the LES Approach

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