Numerical simulation of forced wakes around a cylinder

Ito, Osamu; Yamazaki, T.; Bisaka, T.

doi:10.1016/0142-727x(95)00054-t

Cited by 13 publications

(6 citation statements)

References 8 publications

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“…The number of grids for the zero-grid system was 401 (in the azimuthal direction) × 241 (in the radial direction), while that for the rectangular-grid system was 1841 (in the x-direction) × 161 (in the y-direction). The numerical accuracy of the computation has been examined for the case of unforced cylinder wakes, and comparison of the calculated surface pressure distributions and ow visualization results with the experimental and computational results by other researchers showed good agreement, supporting the reliability of the present code (Inoue et al, 1995).…”

Section: Mathematical Formulation and Numerical Proceduressupporting

confidence: 65%

Secondary vortex streets in two-dimensional cylinder wakes

Ito¹,

Yamazaki

1999

Fluid Dyn. Res.

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Spatially growing wakes behind a circular cylinder at 1406Re61000 are simulated numerically. Two-dimensional, incompressible Navier-Stokes equations are solved using a splitting ÿnite di erence method. Special attention is paid to the development of the vortical structures in far wakes. E ects of subharmonic forcing on the vortical structures are also examined by perturbing the uniform velocity of a free-stream. In both unforced and forced wakes, the transition from the primary Karman vortex street in near wakes to the secondary vortex street in far wakes is observed for all of the Reynolds number cases examined. In unforced cases, rapid decay of the Karman vortices is observed, but clear evidence of merging of the Karman vortices in the transition process was not found. On the other hand, in forced wakes, merging of the Karman vortices is found to play a central role in the transition process. The e ects of the Reynolds number as well as the forcing parameters on the vortical structures in far wakes are also examined.

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Section: Mathematical Formulation and Numerical Proceduressupporting

confidence: 65%

Secondary vortex streets in two-dimensional cylinder wakes

Ito¹,

Yamazaki

1999

Fluid Dyn. Res.

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“…This problem has been numerically investigated by many researchers. 4,[6][7][8][9][10][11][12][13][14][15][16][17] Although the tendency of the drag coefficient as the function of the Reynolds number agrees well with the experiments, the calculated drag coefficients are in general a few percent different from the experimental data. The reason is considered to be a result of the threedimensional effect appearing in the experiment.…”

Section: Flow Around a Two-dimensional Circular Cylindersupporting

confidence: 71%

“…To obtain a mesh and a time step length converged solution for the flow at Re = 9,500, a grid of 2,048 × 256 in the circular and radial directions, respectively, and a dimensionless time step length of 0.00033 should be employed. Recently, Inoue et al 12,13) carefully investigated the vortex streets in the wake region at the Reynolds number up to 1,000. A 401 × 241 grid around the circular cylinder and an 1,841 × 161 grid in the wake region were employed along with a time step length of 0.001 to 0.005 to obtain accurate solutions.…”

Section: Introductionmentioning

confidence: 99%

Computing High Reynolds Number Flows by a Semi-Lagrangian Scheme

Nakanishi¹,

Abe²

2001

Trans. Japan Soc. Aero. S Sci.

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The Semi-Lagrangian (SL) scheme developed for incompressible Navier-Stokes equations written in generalized coordinates has been explored to accurately solve the high Reynolds number flows. The instability related to the advection term of the Navier-Stokes equations is classified into linear instability and nonlinear instability. The former is controlled by the CFL condition, and the latter is due to the aliasing error. The linear instability is naturally eliminated by employment of the SL scheme. The Kawamura scheme is creatively applied to approximate the first derivatives appearing in the Hermite interpolation function to remove the nonlinear instability. The resulting numerical scheme is unconditionally stable for incompressible flows at all Reynolds numbers. Accurate numerical solutions of the unsteady flow around a 2D circular cylinder at Reynolds numbers below 100,000 have been carried out. It was found that this flow has a wide range of wave number modes. Numerous grid numbers and a small time step length must be used to guarantee the accuracy. Furthermore, a very long time average should be conducted to compare the data with the experimental measurement.

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“…Many researchers reported computational and experimental studies of 3D behavior behind a circular cylinder (see for example [1][2][3][4][5][6]). The unsteady behavior at far downstream, including the second phase of the Karman vortex shedding, was particularly emphasized first in [1], followed by [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

“…The unsteady behavior at far downstream, including the second phase of the Karman vortex shedding, was particularly emphasized first in [1], followed by [2][3][4].…”

Section: Introductionmentioning

confidence: 99%

3D simulation and visualization of unsteady wake flow behind a cylinder

Osawa

Tezduyar

1999

J Vis

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In this paper we focus on 3D simulation of unsteady wake flow behind a circular cylinder.We show that in addition to accurate formulations and sufficiently-refined meshes, efficient computing methods are essential components of an effective simulation strategy. We use the Multi-Domain Method (MDM) we developed recently in computation of two cases. At Reynolds number 300, we demonstrate how the MDM enables us to use highly-refined meshes to capture wake patterns which we otherwise cannot fully represent. At Reynolds number 140, we show that with the MDM we can extend our computations sufficiently downstream, and with sufficient accuracy, to successfully capture the second phase of the Karman vortex street, which has been observed in laboratory experiments, and which has double the spacing between the vortices compared to the first phase.

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Numerical simulation of forced wakes around a cylinder

Cited by 13 publications

References 8 publications

Secondary vortex streets in two-dimensional cylinder wakes

Secondary vortex streets in two-dimensional cylinder wakes

Computing High Reynolds Number Flows by a Semi-Lagrangian Scheme

3D simulation and visualization of unsteady wake flow behind a cylinder

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