Extension and Exploration of a Hybrid Turbulence Model on Unstructured Grids

Lynch, C. Eric; Smith, Marilyn J.

doi:10.2514/1.j051177

Cited by 19 publications

(14 citation statements)

References 16 publications

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“…This location has previously been identified as a region of transition from laminar to turbulent flow, contrary to the fully turbulent assumption made in the present methodology and in Sørensen et al . Although the advanced hybrid RANS/LES approach has been demonstrated to predict flow separation in a turbulent flow much more accurately than RANS methods, the significant turbulent kinetic energy near the leading edge generated from the fully turbulent flow assumption prevents the stall from occurring. The inability to stabilize the simulation at the prescribed thrust also confirms the presence of transition, as the fully turbulent assumption would not be physically correct.…”

Section: Resultsmentioning

confidence: 99%

“…A number of turbulence methods are available, including Spalart–Allmaras, Menter k ‐ ω shear‐stress transport (SST) and DES models. A hybrid RANS/LES turbulence simulation method that has been previously shown to improve separated flow field resolution and configuration performance compared with the Menter k ‐ ω SST RANS model has also been incorporated.…”

Section: Computational Methodologymentioning

confidence: 99%

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Unstructured overset incompressible computational fluid dynamics for unsteady wind turbine simulations

Lynch

Smith

2012

Wind Energy

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Overset computational fluid dynamics (CFD) methods are the most sophisticated methods currently available to predict the unsteady motion of wind turbine blades without the need for additional simplifications or restrictions on the turbine operational conditions. An unstructured implementation of the governing equations of motion permits rapid modeling of the salient components, such as nacelles, towers and other localized obstructions of interest. A time‐accurate incompressible formulation accelerates the convergence of the solution, in addition to eliminating the need for low‐Mach number preconditioning, which can be problematic and computationally expensive for time‐accurate simulations. The use of a hybrid Reynolds‐averaged Navier–Stokes/large eddy simulation (RANS/LES) turbulence method is observed to improve the prediction and extent of separation, as well as integrated performance variables for stalled rotors under fully turbulent conditions. Copyright © 2012 John Wiley & Sons, Ltd.

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Section: Resultsmentioning

confidence: 99%

Section: Computational Methodologymentioning

confidence: 99%

Unstructured overset incompressible computational fluid dynamics for unsteady wind turbine simulations

Lynch

Smith

2012

Wind Energy

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“…In this work, HRLES data validated for turbulent bluff body flows including dynamic cases (Refs. 17,[21][22][23][24][25][26] have been employed to generate the quasi-steady data set. The details of the solver, grids, and conditions for the computation of quasi-steady aerodynamic coefficients for 3D rectangular prism and cylinder geometries have been presented previously (Refs.…”

Section: Quasi-steady Aerodynamicsmentioning

confidence: 99%

“…21,27,28), thanks in large part to the hybrid RANS-LES turbulence approach, which resolves large turbulent eddies in the wake (Ref. 22) and to a feature-based unsteady overset grid adaptation capability (Ref. 29).…”

Section: Quasi-steady Aerodynamicsmentioning

confidence: 99%

A Physics-Based, Reduced-Order Aerodynamics Model for Bluff Bodies in Unsteady, Arbitrary Motion

Prosser¹,

Smith²

2015

J Am Helicopter Soc

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A novel reduced-order model for the simulation of bluff bodies in unsteady, arbitrary motion has been developed. The model is physics-based, meaning that it is derived from known fundamental aerodynamic phenomena of bluff bodies instead of response fitting of experimental data. This physics-based approach is essential to ensure that the model is applicable to new, untested configurations. We describe the development of a physics-based model, including detailed explanations of the fundamental aerodynamic phenomena and how they are modeled in simulation. The reduced-order model is evaluated by application to rotorcraft-tethered loads and validated against much more expensive high-fidelity computational fluid dynamics simulations and flight tests. Excellent correlation in the predictions of aerodynamic forces and moments, as well as the dynamic response, is observed, while the computational cost has been reduced by several orders of magnitude relative to high-fidelity computational-fluid-dynamics-based simulations. Additionally, the important role that unsteady aerodynamics play in bluff body dynamics and instability is demonstrated.

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“…Two interesting items are found. In the literature, it is widely known that for unstructured vertex-centered solver using median-dual control volume (hereafter denoted as MD-VC for short), if stretched triangular/tetrahedral cells are used to mesh the boundary layer, then the solver suffers from excessive dissipation caused by the misalignment between the mesh and the flow [17][18][19][20][21]. However, in this work, it is very interesting to find that the weighted meshless solver is much less sensitive to the misalignment, and the numerical dissipation is much smaller.…”

mentioning

confidence: 99%

Analysis of a meshless solver for high Reynolds number flow

Chen

Yamamoto

Nakahashi

2012

Numerical Methods in Fluids

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SUMMARYIn this paper, the extension of an upwind least‐square based meshless solver to high Reynolds number flow is explored, and the properties of the meshless solver are analyzed both theoretically and numerically. Existing works have verified the meshless solver mostly with inviscid flows and low Reynolds number flows, and in this work, we are interested in the behavior of the meshless solver for high Reynolds number flow, especially in the near‐wall region. With both theoretical and numerical analysis, the effects of two parameters on the meshless solver are identified. The first one is the misalignment effect caused by the significantly skewed supporting points, and it is found that the meshless solver still yields accurate prediction. It is a very interesting property and is opposite to the median‐dual control volume based vertex‐centered finite volume method, which is known to give degraded result with stretched triangular/tetrahedral cells in the near‐wall region. The second parameter is the curvature, and according to theoretical analysis, it is found in the region with both large aspect ratio and curvature, and the streamwise residual is less affected; however, the wall‐normal counterpart suffers from accuracy degradation. In this paper, an improved method that uses a meshless solver for the streamwise residual and finite difference for wall‐normal residual is developed. This method is proved to be less sensitive to the curvature and provides improved accuracy. This work presents an understanding of the meshless solver for high Reynolds number flow computation, and the analysis in this paper is verified with a series of numerical experiments. Copyright © 2012 John Wiley & Sons, Ltd.

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Extension and Exploration of a Hybrid Turbulence Model on Unstructured Grids

Cited by 19 publications

References 16 publications

Unstructured overset incompressible computational fluid dynamics for unsteady wind turbine simulations

Unstructured overset incompressible computational fluid dynamics for unsteady wind turbine simulations

A Physics-Based, Reduced-Order Aerodynamics Model for Bluff Bodies in Unsteady, Arbitrary Motion

Analysis of a meshless solver for high Reynolds number flow

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