On the parameter β=Re/KC=D2/νT

Sarpkaya, Turgut

doi:10.1016/j.jfluidstructs.2005.08.007

Cited by 29 publications

(4 citation statements)

References 20 publications

(23 reference statements)

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“…The importance of this parameter was realized in numerous ow problems such as oscillatory separated ows over blu bodies. A recent summary regarding this non-dimensional parameter is given by Sarpkaya [25]. This parameter could be e ectively extended to the present problem, which is concerned with viscous e ects in unsteady pipe ow, by noting that the periodic time for unsteady ows in elastic pipes is of the order (L=a).…”

Section: Non-dimensional Parameter For Viscous Effects In Unsteady Pimentioning

confidence: 99%

Runge–Kutta time‐stepping schemes with TVD central differencing for the water hammer equations

Wahba

2006

Numerical Methods in Fluids

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SUMMARYIn the present study, Runge-Kutta schemes are used to simulate unsteady ow in elastic pipes due to sudden valve closure. The spatial derivatives are discretized using a central di erence scheme. Secondorder dissipative terms are added in regions of high gradients while they are switched o in smooth ow regions using a total variation diminishing (TVD) switch. The method is applied to both oneand two-dimensional water hammer formulations. Both laminar and turbulent ow cases are simulated.Di erent turbulence models are tested including the Baldwin-Lomax and Cebeci-Smith models. The results of the present method are in good agreement with analytical results and with experimental data available in the literature. The two-dimensional model is shown to predict more accurately the frictional damping of the pressure transient. Moreover, through order of magnitude and dimensional analysis, a non-dimensional parameter is identiÿed that controls the damping of pressure transients in elastic pipes.

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Section: Non-dimensional Parameter For Viscous Effects In Unsteady Pimentioning

confidence: 99%

Runge–Kutta time‐stepping schemes with TVD central differencing for the water hammer equations

Wahba

2006

Numerical Methods in Fluids

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“…The system can be described by two dimensionless numbers, the Keulegan-Carpenter number, KC ¼ U 0 T=D, and the Reynolds number, Re ¼ U 0 D=n, where U 0 is the maximum cylinder velocity, T the cylinder oscillation period, D the cylinder diameter and n the kinematic viscosity of the fluid. The ratio b ¼ Re=KC ¼ D 2 =ðnTÞ, named frequency parameter or Stokes number (see Sarpkaya, 2005), can also be used instead of Re.…”

Section: Introductionmentioning

confidence: 99%

“…The classical approach to describe the force in the general case consists in determining C m and C d versus KC and b or Re (e.g. Obasaju et al, 1988;Justesen, 1991;Smith and Stansby, 1991;Lin et al, 1996;Sun and Dalton, 1996;Zhang and Zhang, 1997;Dütsch et al, 1998;Iliadis and Anagnostopoulos, 1998;Uzunoǧlu et al, 2001;Sarpkaya, 2005). However, significant discrepancies appear for higher KC.…”

Section: Introductionmentioning

confidence: 99%

Characterization of long time fluctuations of forces exerted on an oscillating circular cylinder at KC=10

Duclercq

Broc

Cadot

2011

Journal of Fluids and Structures

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a b s t r a c tFlow dynamics, in-line and transverse forces exerted on an oscillating circular cylinder in a fluid initially at rest are studied by numerical resolution of the two-dimensional Navier-Stokes equations. The Keulegan-Carpenter number is held constant at KC = 10 and Re is increased from 40 to 500. For the different flow regimes, links between flow spatio-temporal symmetries and force histories are established. Besides simulations of long duration show that in two ranges of Re, forces exhibit low frequency fluctuations compared to the cylinder oscillation frequency. Such observations have been only mentioned in the literature and are more deeply examined here. In both ranges, force fluctuations correspond to oscillations of the front and rear stagnation points on the cylinder surface. However, they occur in flow regimes whose basic patterns (V-shaped mode or diagonal mode) have different symmetry features, inducing two distinct behaviors. For 80 r Re r 100, fluctuations are related to a spectral broadening of the harmonics and to a permutation between three vortex patterns (V-shaped, transverse and oblique modes). In the second range 150 r Re r 280, amplitude fluctuations are correlated to the appearance of low frequency peaks interacting with harmonics of the cylinder frequency. Fluctuations are then a combination of a wavy fluctuation and an amplitude modulation. The carrier frequency corresponding to the wavy fluctuation depends on Re and is related to a fluid characteristic time; the modulation frequency is independent of Re and equal to 1/4 of the cylinder oscillation frequency.

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“…The ratio of Reynolds number and the Keulegan-Carpenter number is known as the frequency parameter [Sarpkaya, 2005] and is given by…”

Section: Flow Past a Cylindermentioning

confidence: 99%

On the dynamics of flow past a cylinder: Implications for CTD package motions and measurements

Munday

Meredith

2017

JGR Oceans

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During the collection of ship‐based observations, heaving of the vessel may lead to variation in the descent rate of a CTD package. This can result in the package being pulled upward through previously sampled water, leading to difficult to quantify errors due to the complex wake. To reduce this problem to one of manageable stature, we use the simple paradigm of two‐dimensional flow past a cylinder. By using a tracer with a gradient along the flow, we quantify the effect of the cylinder on its distribution and the impact of postprocessing. At high Reynolds numbers, over 200, uniform translation leads to a small error in the tracer value. This error is likely negligible at the much higher Reynolds number of the ocean. When the flow is oscillated longitudinally, there are two main sources of error; attached vortices may propagate around the cylinder and/or shed vortices may translate into the path of the cylinder. Postprocessing by removing records from previous pressure levels removes much of the first error, due to it occurring as the package ascends. However, the second source of error is more difficult to remove, due to it occurring when the package is once again descending. In general, results indicate that long‐period oscillations are preferable. While the magnitude of the errors are comparable to those from short‐period oscillations, they are spread farther apart in time and space and the overall effect is to localize the errors in small regions of the final depth profile.

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On the parameter β=Re/KC=D2/νT

Cited by 29 publications

References 20 publications

Runge–Kutta time‐stepping schemes with TVD central differencing for the water hammer equations

Runge–Kutta time‐stepping schemes with TVD central differencing for the water hammer equations

Characterization of long time fluctuations of forces exerted on an oscillating circular cylinder at KC=10

On the dynamics of flow past a cylinder: Implications for CTD package motions and measurements

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