Present State of Art on Pulsatile Flow Theory. Part 1. Laminar and Transitional Flow Regimes.

Gündoğdu, Mehmet Yaşar; Çarpınlıoǧlu, Melda Özdinç

doi:10.1299/jsmeb.42.384

Cited by 79 publications

(33 citation statements)

References 44 publications

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“…The domain size is l x ϫ l y ϫ h =4ϫ 2 ϫ 1 for all simulations. Consequently, the Reynolds number is Re = U 0 2 / =10 6 or using the Stokes boundary layer thickness Re S = ͱ 2U 0 / ͱ = 1.4ϫ 10 3 . The KeuleganCarpenter number is for all cases KC= U 0 / h = 80.…”

Section: Turbulence Driven By a Free-surface Stressmentioning

confidence: 99%

“…We are here particularly interested in the vertical variation of the flow in the fluid column. The flow in the estuary is mainly driven by the tide with the relating volume flow ranging from 12 000 m 3 / s at the point the Schelde river enters to 80 000 m 3 The Reynolds number based on the height of the domain, Re h = U 0 h / with the kinematic viscosity, is of order of O͑10 6 ͒ -O͑10 7 ͒, indicating that the flow is turbulent. Turbulent time scales are much smaller than the tidal period as indicated by the large Keulegan-Carpenter number, KC= U 0 / h = O͑100͒, which expresses the ratio between the tidal period and the advection time scale.…”

Section: Introductionmentioning

confidence: 99%

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Turbulent oscillating channel flow subjected to a free-surface stress

2010

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The channel flow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean flow develops. The Reynolds number is typically Reω=106 and the Keulegan–Carpenter number—the ratio between the oscillation period and advection time scale—is KC=80. Results compare favorably to the data from direct numerical simulations obtained over a single period. A slowly pulsating mean flow occurs with the turbulent flow essentially being statistically steady. Logarithmic boundary layers are present at both the bottom wall and the free surface. Turbulent streaks are observed in the bottom and free-surface layer. The viscous sublayer below the free surface is, however, much thinner. This observation is verified by simulations we performed for a purely wind-driven channel flow. For the oscillating flow, additional low-speed splats (localized regions of upwelling) occur at the free surface when the mean velocity and stress are in the same direction.

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Section: Turbulence Driven By a Free-surface Stressmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Turbulent oscillating channel flow subjected to a free-surface stress

2010

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“…The higher error of the system of mechanical energy equations derived from the integral energy (16) is caused by nonlinearities. The integral solution (15) is in excellent agreement with the finite difference solution in the region α = 1-20 which is a part of the intermediate region of pulsatile flow [5] , [6]. Another type of gradient P (a symmetric triangular wave) was applied to the system of equations (15), (16) and also to the finite difference method.…”

Section: Resultsmentioning

confidence: 65%

“…Szymanski [3] employed a similar technique, and obtained an analytical solution to the momentum equation for the flow driven by a pressure gradient dp/dx = 0 for t ≤ 0 and dp/dx = C for t > 0, where C was constant. An extended review of the literature dealing with laminar pulsatile flow, which presents the current state of theoretical and experimental knowledge was thoroughly drafted by [5] and supplemented in [6].…”

Section: Introductionmentioning

confidence: 99%

Integral Methods for Describing Pulsatile Flow

2016

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Abstract. This paper presents an approximate solution of the pulsatile flow of a Newtonian fluid in the laminar flow regime in a rigid tube of constant diameter. The model is represented by two ordinary differential equations. The first equation describes the time evolution of the total flow rate, and the second equation characterizes the reverse flow near the wall. These equations are derived from the momentum balance equation and from the kinetic energy equation, respectively. The accuracy of the derived equations is compared with a solution in which the finite difference method is applied to a partial differential equation.

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“…There are number of publications in the literature, describing investigations of pulsating pipe flows as indicated by the recent review articles of Ç arpınlıoglu and Gündogdu (1) and Gündogdu and Ç arpınlıoglu (2), (3) . But the experimental investigations carried in the literature on pulsating flows compared to steady flow investigations, are rather less in number.…”

Section: Introductionmentioning

confidence: 99%

Pulsating Flows: Experimental Equipment and Its Application

Ünsal

Durst

2006

JSME international journal. Ser. B, Fluids and thermal engineer

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Investigations of time-dependent laminar and transitional flows need accurate and reproducible generation of the flow as a function of time. For this purpose, an electronically controlled air valve, with which the mass flow rate is controlled, was designed and built. The working principle and lay-out of the valve are explained and the performance of the valve is demonstrated. It was found that with the present equipment one can study any non-periodic and periodic flow and the flow can be adjusted to be laminar, transitional and turbulent. The investigations on laminar and transitional time-dependent flows are reported. Laminar flow investigations showed that the generated sinusoidal mass flow rates agree well with that of analytical solution. Non-periodic transient and periodic sinusoidal pulsatile transitional flows were investigated. It was shown that elucidation of the transition in non-periodic transient flows may help in understanding the transition in periodic flows.

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Present State of Art on Pulsatile Flow Theory. Part 1. Laminar and Transitional Flow Regimes.

Cited by 79 publications

References 44 publications

Turbulent oscillating channel flow subjected to a free-surface stress

Turbulent oscillating channel flow subjected to a free-surface stress

Integral Methods for Describing Pulsatile Flow

Pulsating Flows: Experimental Equipment and Its Application

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