Steady streaming of fluid in the entrance region of a tube during oscillatory flow

1999 ◽  
Vol 11 (10) ◽  
pp. 2957-2962 ◽  
Author(s):  
Irwin S. Goldberg ◽  
Zongqin Zhang ◽  
Minhtan Tran
Keyword(s):  
Oscillatory Flow ◽  
Entrance Region ◽  
Steady Streaming

scholarly journals Wave-Induced Oscillatory Flow Over a Sloping Rippled Bed

Water ◽  
2019 ◽  
Vol 11 (8) ◽  
pp. 1618 ◽  
Author(s):  
Carla Faraci ◽  
Pietro Scandura ◽  
Carmelo Petrotta ◽  
Enrico Foti
Keyword(s):  
Oscillatory Flow ◽  
Thin Layers ◽  
Steady Streaming ◽  
Wave Flume ◽  
Flow Asymmetry ◽  
Horizontal Part ◽  
Cohesive Bed ◽  
Sloping Beach ◽  
Wave Induced ◽  
Rippled Bed

In this paper, the findings of an experimental analysis aimed at investigating the flow generated by waves propagating over a fixed rippled bed within a wave flume are reported. The bottom of the wave flume was constituted by horizontal part followed by a 1:10 sloping beach. Bedforms were generated in a previous campaign performed with loose sand, and then hardened by means of thin layers of concrete. The flow was acquired through a Vectrino Profiler along two different ripples, one located in the horizontal part of the bed and the second over the sloping beach. It was observed that, on the horizontal bed, near the bottom, ripple lee side triggered the appearance of an onshore directed steady streaming, whereas ripple stoss side gave rise to an offshore directed steady streaming. On the sloping bed, a strong return current appears at all positions, interacting with the rippled bottom. The turbulence is non-negligible within the investigated water depth, particularly when velocities were onshore directed, due to flow asymmetry. Turbulence caused a considerable flow stirring which, above a non-cohesive bed, could lift the sediment up in the water column and give rise to a strong sediment transport.

Unsteady flow about a sphere at low to moderate Reynolds number. Part 1. Oscillatory motion

1994 ◽  
Vol 277 ◽  
pp. 347-379 ◽  
Author(s):  
Eugene J. Chang ◽  
Martin R. Maxey
Keyword(s):  
Reynolds Number ◽  
Unsteady Flow ◽  
Steady Flow ◽  
Oscillatory Flow ◽  
Reynolds Numbers ◽  
Oscillatory Motion ◽  
Rigid Sphere ◽  
Flow Conditions ◽  
Steady Streaming ◽  
Moderate Reynolds Number

A direct numerical simulation, based on spectral methods, has been used to compute the time-dependent, axisymmetric viscous flow past a rigid sphere. An investigation has been made for oscillatory flow about a zero mean for different Reynolds numbers and frequencies. The simulation has been verified for steady flow conditions, and for unsteady flow there is excellent agreement with Stokes flow theory at very low Reynolds numbers. At moderate Reynolds numbers, around 20, there is good general agreement with available experimental data for oscillatory motion. Under steady flow conditions no separation occurs at Reynolds number below 20; however in an oscillatory flow a separation bubble forms on the decelerating portion of each cycle at Reynolds numbers well below this. As the flow accelerates again the bubble detaches and decays, while the formation of a new bubble is inhibited till the flow again decelerates. Steady streaming, observed for high frequencies, is also observed at low frequencies due to the flow separation. The contribution of the pressure to the resultant force on the sphere includes a component that is well described by the usual added-mass term even when there is separation. In a companion paper the flow characteristics for constant acceleration or deceleration are reported.

Steady streaming around a circular cylinder in an oscillatory flow

2009 ◽  
Vol 36 (14) ◽  
pp. 1089-1097 ◽  
Author(s):  
Hongwei An ◽  
Liang Cheng ◽  
Ming Zhao
Keyword(s):  
Circular Cylinder ◽  
Oscillatory Flow ◽  
Steady Streaming

scholarly journals Steady streaming around a cylinder pair

2016 ◽  
Vol 472 (2195) ◽  
pp. 20160522 ◽  
Author(s):  
W. Coenen
Keyword(s):  
Reynolds Number ◽  
Oscillatory Flow ◽  
Circular Cylinders ◽  
Flow Topology ◽  
Order Unity ◽  
Steady Streaming ◽  
Stokes Layer ◽  
Streaming Velocity ◽  
Gap Width ◽  
Streaming Motion

The steady streaming motion that appears around a pair of circular cylinders placed in a small-amplitude oscillatory flow is considered. Attention is focused on the case where the Stokes layer thickness at the surface of the cylinders is much smaller than the cylinder radius, and the streaming Reynolds number is of order unity or larger. In that case, the steady streaming velocity that persists at the edge of the Stokes layer can be imposed as a boundary condition to numerically solve the outer streaming motion that it drives in the bulk of the fluid. It is investigated how the gap width between the cylinders and the streaming Reynolds number affect the flow topology. The results are compared against experimental observations.

scholarly journals Flow in the Entrance Region of a Porous Pipe : 4th Report: Oscillatory Flow

1985 ◽  
Vol 28 (237) ◽  
pp. 420-427
Author(s):  
Takahiko TANAHASHI ◽  
Tsuneyo ANDO ◽  
Hideki KAWAI ◽  
Teruyuki KAWASHIMA
Keyword(s):  
Oscillatory Flow ◽  
Entrance Region ◽  
Porous Pipe

Oscillatory Flow Between Two Hemispheres for Shearing Protein Solution

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Dejuan Kong ◽  
Anita Penkova ◽  
Satwindar Singh Sadhal
Keyword(s):  
Shear Rate ◽  
Oscillatory Flow ◽  
Molecular Mechanisms ◽  
Outer Boundary ◽  
Experimental System ◽  
Theoretical Background ◽  
Physical Factors ◽  
Protein Solution ◽  
Steady Streaming ◽  
And Control

Protein aggregation, one of the common molecular mechanisms for neurodegenerative diseases, is affected by variety of physical factors, one of which is shear rate of protein solution. This paper provides theoretical background on the shear rate in the experimental system we have proposed to effectively apply and control shear. We carried out the mathematical analysis of the flow field resulted from torsional or transverse oscillation on the outer boundary between two concentric hemispheres by perturbation method. We have obtained analytical solutions for the velocity field, the shear rate, and the flow pattern of steady streaming created by the nonlinear interaction of the oscillatory flow.

Oscillatory flow over a cylinder resting on a plane boundary

1996 ◽  
Vol 7 (6) ◽  
pp. 545-558 ◽  
Author(s):  
M. F. Wybrow ◽  
N. Riley
Keyword(s):  
Circular Cylinder ◽  
Boundary Layers ◽  
Outer Layer ◽  
Oscillatory Flow ◽  
Outer Boundary ◽  
Reynolds Numbers ◽  
Plane Boundary ◽  
Simple Experiment ◽  
Steady Streaming ◽  
Streaming Motion

Oscillatory flow over a circular cylinder, or part-cylinder, placed on a plane boundary, when the Strouhal and streaming Reynolds numbers are large, is considered. The solution is developed in matching inner and outer boundary layers. A steady streaming motion in the outer layer can lead to a net flow away from the cylinder along the plane boundary. A simple experiment substantiates this prediction, and the implications for bed-scouring are examined.

Centrifugal instability of an oscillatory flow over periodic ripples

1990 ◽  
Vol 217 ◽  
pp. 1-32 ◽  
Author(s):  
Tetsu Hara ◽  
Chiang C. Mei
Keyword(s):  
Oscillatory Flow ◽  
Sandy Beach ◽  
Three Dimensional ◽  
Small Region ◽  
Oscillating Flow ◽  
Two Dimensional ◽  
Steady Streaming ◽  
Centrifugal Instability ◽  
Two Dimensional Flow ◽  
Finite Slope

An oscillating flow over a sandy beach can initiate and enhance the formation of bed ripples, with crests perpendicular to the direction of the ambient oscillation. Under certain circumstances, bridges may develop to span adjacent ripple crests, resulting in a brick pattern. It has been suggested that the onset of this transition is due to a three-dimensional centrifugal instability of an otherwise two-dimensional flow over periodic long-crested ripples. Here we analyse theoretically such an instability by assuming that the ripples are rigid and smooth. Two complementary cases are studied. We first consider a weak ambient oscillation over ripples of finite slope in Case (i). The three-dimensional disturbance is found to be localized in a small region either along the crests or along the troughs. In Case (ii) we analyse finite oscillations over ripples of mild slope. The region influenced by the instability is now comparable with a ripple wavelength and the unstable disturbance along adjacent ripples may interact with each other. Four types of harmonic and subharmonic instabilities are found. The associated steady streaming close to the ripple surface shows various tendencies of possible sand accumulations, some of which appear to be qualitatively relevant to the initiation of brick-patterned ripples.

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