An investigation of parallel implicit solution algorithms for incompressible flows on multielement unstructured topologies

Hyams, Daniel; Sreenivas, Kidambi; Sheng, Chunhua; Briley, W. R.; Marcum, David L.; Whitfield, David L.

doi:10.2514/6.2000-271

Cited by 107 publications

(55 citation statements)

References 17 publications

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“…The 2nd-order spatially accurate Roe flux [12] is utilized. A directional derivative viscous method is used to calculate the viscous flux [13]. Characteristic variable boundary conditions [14] with specified free stream wind velocities are applied at the far field boundaries in the computational domain.…”

Section: Computational Fluid Dynamics Code: Umentioning

confidence: 99%

Computational Aerodynamic Analysis of Offshore Upwind and Downwind Turbines

Zhao

Sheng

Afjeh

2014

Journal of Aerodynamics

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Aerodynamic interactions of the model NREL 5 MW offshore horizontal axis wind turbines (HAWT) are investigated using a highfidelity computational fluid dynamics (CFD) analysis. Four wind turbine configurations are considered; three-bladed upwind and downwind and two-bladed upwind and downwind configurations, which operate at two different rotor speeds of 12.1 and 16 RPM. In the present study, both steady and unsteady aerodynamic loads, such as the rotor torque, blade hub bending moment, and base the tower bending moment of the tower, are evaluated in detail to provide overall assessment of different wind turbine configurations. Aerodynamic interactions between the rotor and tower are analyzed, including the rotor wake development downstream. The computational analysis provides insight into aerodynamic performance of the upwind and downwind, two-and three-bladed horizontal axis wind turbines.

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Section: Computational Fluid Dynamics Code: Umentioning

confidence: 99%

Computational Aerodynamic Analysis of Offshore Upwind and Downwind Turbines

Zhao

Sheng

Afjeh

2014

Journal of Aerodynamics

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“…For the mixed element meshes, the calculation of the diffusive fluxes needs to be compatible with the edge-based data structure, where solutions and their gradients are stored at the two vertices of an edge. One way to evaluate the gradients on the face of a control volume is called directional derivative method [19]. The second approach is called a normal directive method, which imposes positivity along the normal direction of a median dual face.…”

Section: Diffusive Flux Evaluationmentioning

confidence: 99%

“…The solution of the sparse system of equations is obtained by a relaxation scheme in which Δ q n+1,m is obtained through a sequence of iterations, {Δ q n+1,m } i , which converge to Δ q n+1,m . There are several variations of classic relaxation procedures that have been used in the past for solving this linear system of equations [18][19][20]. In this study, a symmetric implicit Gauss-Seidel procedure [19] is used.…”

Section: Gauss-seidel Relaxationmentioning

confidence: 99%

“…There are several variations of classic relaxation procedures that have been used in the past for solving this linear system of equations [18][19][20]. In this study, a symmetric implicit Gauss-Seidel procedure [19] is used. To clarify the scheme, the system matrix is first written as a linear combination of matrices representing the diagonal, upper triangular, and lower triangular parts at each time step: …”

Section: Gauss-seidel Relaxationmentioning

confidence: 99%

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A Preconditioned Method for Rotating Flows at Arbitrary Mach Number

Sheng

2011

Modelling and Simulation in Engineering

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An improved preconditioning is proposed for viscous flow computations in rotating and nonrotating frames at arbitrary Mach numbers. The key to the current method is the use of both free stream Mach number and rotating Mach number to construct a preconditioning matrix, which is applied to the compressible governing equations written in terms of primitive variables. A Fourier analysis is conducted that reveals the efficacy of the modified preconditioning. Numerical approximations for the convective and diffusive fluxes are detailed based on the preconditioned system of equations. A set of boundary conditions using characteristic variables are described for internal and external flow computations. Numerical validations are performed on four realistic viscous flows in both fixed and rotating frames. The results indicated that the modified preconditioning has a superior performance compared to the original method to predict flows from extremely low to supersonic Mach numbers.

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“…The gradients used in the linear reconstruction can influence the numerical dissipation and can dissipate vortices present in the flow field. Two of the most commonly used methods are the weighted averaging together with Gauss theorem [8]and least square approach [9,10,11].…”

Section: Gradient Estimationmentioning

confidence: 99%

Aero-Optics Code Development: Experimental Databases and AVUS Code Improvements

Sherer¹

2009

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An investigation of parallel implicit solution algorithms for incompressible flows on multielement unstructured topologies

Cited by 107 publications

References 17 publications

Computational Aerodynamic Analysis of Offshore Upwind and Downwind Turbines

Computational Aerodynamic Analysis of Offshore Upwind and Downwind Turbines

A Preconditioned Method for Rotating Flows at Arbitrary Mach Number

Aero-Optics Code Development: Experimental Databases and AVUS Code Improvements

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