Further Analysis of High-Order Overset Grid Method with Applications

Sherer, Scott E.

doi:10.2514/6.2003-3839

Cited by 30 publications

(7 citation statements)

References 31 publications

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“…Additional validation was also provided by comparison with numerical results obtained for various two-and three-cylinder configurations via a finite-difference timedomain computational aeroacoustics code. 17,18 …”

Section: A Implementation and Validationmentioning

confidence: 98%

“…Because it is analytic, this approach is useful for establishing benchmark scattering solutions that may be used to assess the accuracy of computational aeroacoustic solvers developed for geometrically complex configurations. [17][18][19] The use of solutions generated by a spatially distributed source is preferred over a line source or plane-wave solution for this purpose due to the presence of a singularity in the total field for the former and the requirement to propagate the incident wave into the domain of interest from beyond its boundaries when using the total field formulation for the latter. This analytic approach may also prove amenable to parametric studies of the scattering behavior of systems involving multiple-cylinder geometries.…”

Section: Introductionmentioning

confidence: 99%

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Scattering of sound from axisymetric sources by multiple circular cylinders

Sherer

2004

The Journal of the Acoustical Society of America

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A general analytic method for calculating the scattering of sound by multiple rigid circular cylinders arranged in an arbitrary parallel configuration is presented. The sound scattered by this collection of cylinders is generated by a time-periodic, spatially distributed, axisymmetric source located within the domain of interest. A Hankel transform method is used to calculate the incident field, while separation of variables is used to obtain the scattered fields from each cylinder in the collection. The unknown scattering coefficients are determined through the use of general addition theorems that allows the various fields to be readily transformed between coordinate systems. The method is validated using various two-, three-, and four-cylinder configurations, and the number of coefficients that must be retained in the truncated series is examined. Benchmark configurations consisting of two- and three-cylinder systems with cylinders of varying radii are also presented. These solutions have been used to validate computational aeroacoustic solvers developed for complex geometries.

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Section: A Implementation and Validationmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Scattering of sound from axisymetric sources by multiple circular cylinders

Sherer

2004

The Journal of the Acoustical Society of America

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“…Any spurious waves that are amplified by the high-order onesided filters in this wave space range will tend to be removed by the interior filter as they propagate away from the boundary. If the numerical stability associated with the one-sided boundary filters is an issue, the peak amplification values may also be decreased by increasing the value of the filter coefficient f at the points near the boundary [15,24].…”

Section: Filtering Formulasmentioning

confidence: 99%

Multi‐resolution implicit large eddy simulations using a high‐order overset‐grid approach

Sherer

Visbal

2007

Numerical Methods in Fluids

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SUMMARYA parallel, high-order, overset-grid method is validated for use in large eddy simulation (LES) through its application to fundamental turbulent flow problems. The current method employs a high-order, compact finite-difference approach to evaluate spatial derivatives, with up to tenth-order low-pass filters used to remove high-frequency spurious wave content. These filters have also been found to be effective in modelling the dissipation that occurs at the unresolved scales in the flow for LES simulations. Temporal integration is based on an implicit, approximately factored and diagonalized, second-order algorithm, which reduces the time-step constraints present in explicit time-marching methods for wall-bounded viscous flows. Parallelization, geometric complexity, and local grid refinement are all addressed through the use of an overset-grid approach, with grid communication provided by high-order Lagrangian interpolation. The problems investigated in this work include fully turbulent channel flow at Re = 590 and 1017, and the transitional wake generated by flow over a single circular cylinder at Re D = 3900. The results obtained with the current approach are validated against well-resolved benchmark calculations or experiments and the impact of the order-of-accuracy of the interpolation method is investigated. The benefits obtained by using the general overset-grid technique to reduce grid point requirements compared to single-grid simulations are also examined. It is shown that for the problems considered in this work, substantial grid-point savings may be obtained with an overset-grid approach compared to a single-grid approach, and that the use of high-order interpolation at overset boundaries is important in maintaining overall solution accuracy.

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“…This includes the upstream and downstream domains, the turbine blade grid, the refined-mesh region, all zones surrounding the jet, and the interior jet nozzle. The interpolation approach for high-order numerical solutions has been successfully applied by Sherer [50] for the simulation of fluid dynamic and acoustic problems. As stated previously, periodic conditions were invoked in the spanwise direction.…”

Section: Boundary Conditionsmentioning

confidence: 99%

Numerical Study of Active Flow Control for a Transitional Highly Loaded Low-Pressure Turbine

Rizzetta

Visbal

2006

Journal of Fluids Engineering

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Active control was simulated numerically for the subsonic flow through a highly loaded low-pressure turbine. The configuration approximated cascade experiments that were conducted to investigate a reduction in turbine stage blade count, which can decrease both weight and mechanical complexity. At a nominal Reynolds number of 25,000 based upon axial chord and inlet conditions, massive separation occurred on the suction surface of each blade due to uncovered turning. Vortex generating jets were then used to help mitigate separation, thereby reducing wake losses. Computations were performed using both steady blowing and pulsed mass injection to study the effects of active flow control on the transitional flow occurring in the aft-blade and near-wake regions. The numerical method utilized a centered compact finite-difference scheme to represent spatial derivatives, that was used in conjunction with a low-pass Pade-type nondispersive filter operator to maintain stability. An implicit approximately factored time-marching algorithm was employed, and Newton-like subiterations were applied to achieve second-order temporal accuracy. Calculations were carried out on a massively parallel computing platform, using domain decomposition to distribute subzones on individual processors. A high-order overset grid approach preserved spatial accuracy in locally refined embedded regions. Features of the flowfields are described, and simulations are compared with each other, with available experimental data, and with a previously obtained baseline case for the noncontrolled flow. It was found that active flow control was able to maintain attached flow over an additional distance of 19–21% of the blade chord, relative to the baseline case, which resulted in a reduction of the wake total pressure loss coefficient of 53–56%.

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Further Analysis of High-Order Overset Grid Method with Applications

Cited by 30 publications

References 31 publications

Scattering of sound from axisymetric sources by multiple circular cylinders

Scattering of sound from axisymetric sources by multiple circular cylinders

Multi‐resolution implicit large eddy simulations using a high‐order overset‐grid approach

Numerical Study of Active Flow Control for a Transitional Highly Loaded Low-Pressure Turbine

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