Shear Flow of a Viscous Fluid over a Cavity with a Pulsating Gas Bubble

2020 ◽  
Vol 65 (7) ◽  
pp. 242-245
Author(s):  
A. I. Ageev ◽  
A. N. Osiptsov
Keyword(s):  
Shear Flow ◽  
Viscous Fluid ◽  
Gas Bubble

The Effect of Shear Flow and Dissolved Gas Diffusion on the Cavitation in a Submerged Journal Bearing

2000 ◽  
Vol 123 (3) ◽  
pp. 494-500 ◽  
Author(s):  
M. Groper ◽  
I. Etsion
Keyword(s):  
Mass Transfer ◽  
Shear Flow ◽  
Mass Transport ◽  
Transport Mechanism ◽  
Journal Bearing ◽  
Gas Diffusion ◽  
Gas Bubble ◽  
Dissolved Gas ◽  
Rotating Shaft ◽  
Mass Transfer Mechanism

Two possible, long standing speculated mechanisms are theoretically investigated in an attempt to understand previous experimental observations of pressure build up in the cavitation zone of a submerged journal bearing. These mechanisms are (1) the shear of the cavity gas bubble by a thin lubricant film dragged through the cavitation zone by the rotating shaft and (2) the mass transfer mechanism which dictates the rate of diffusion of dissolved gas out of and back into the lubricant. A comparison with available experimental results reveals that while the cavitation shape is fairly well predicted by the “shear” mechanism, this mechanism is incapable of generating the level of the experimentally measured pressures, particularly towards the end of the cavitation zone. The “mass transport” mechanism is found inadequate to explain the experimental observations. The effect of this mechanism on the pressure build up in the cavitation zone can be completely ignored.

Effect of fluid forcing on vestibular hair bundles

2005 ◽  
Vol 15 (5-6) ◽  
pp. 263-278
Author(s):  
J.-H. Nam ◽  
J.R. Cotton ◽  
J.W. Grant
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Hair Bundle ◽  
Structural Components ◽  
The Finite Element Method ◽  
Fluid Drag ◽  
Tip Link ◽  
Single Force

A dynamic 3-D hair bundle model including inertia and viscous fluid drag effects based on the finite element method is presented. Six structural components are used to construct the hair bundle – kinocilium, stereocilia, upper lateral links, shaft links, tip links, and kinocilial links. Fluid drag is distributed on the surface of cilia columns. Bundle mechanics are analyzed under two distinct loading conditions: (1) drag caused by the shear flow of the surrounding endolymph fluid (fluid-forced), (2) a single force applied to the tip of the kinocilium (point-forced). A striolar and a medial extrastriolar vestibular hair cell from the utricle of a turtle are simulated. The striolar cell bundle shows a clear difference in tip link tension profile between fluid-forced and point-forced cases. When the striolar cell is fluid forced, it shows more evenly distributed tip link tensions and is far more sensitive, responding like an on/off switch. The extrastriolar cell does not show noticeable differences between the forcing types. For both forcing conditions, the extrastriolar cell responds serially – the nearest tip links to the kinocilium get tensed first, then the tension propagates to the farther tip links.

Slender-body theory for steady sheared plumes in very viscous fluid

2008 ◽  
Vol 612 ◽  
pp. 21-44 ◽  
Author(s):  
ROBERT J. WHITTAKER ◽  
JOHN R. LISTER
Keyword(s):  
Simple Model ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Experimental Studies ◽  
Slender Body ◽  
Slender Body Theory ◽  
Dimensionless Parameters ◽  
Dynamical Regimes ◽  
Body Theory ◽  
Good Agreement

A simple model based on slender-body theory is developed to describe the deflection of a steady plume by shear flow in very viscous fluid of the same viscosity. The key dimensionless parameters measuring the relative strengths of the shear, diffusion and source flux are identified, which allows a number of different dynamical regimes to be distinguished. The predictions of the model show good agreement with many, but not all, observations from previous experimental studies. Possible reasons for the discrepancies are discussed.

Shear flow instability in a conducting viscous fluid

1973 ◽  
Vol 57 (3) ◽  
pp. 481-490
Author(s):  
B. Roberts
Keyword(s):  
Magnetic Field ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Flow Instability ◽  
Approximate Solutions ◽  
Viscous Fluids ◽  
Neutral Stability ◽  
Parallel Magnetic Field ◽  
The Stability ◽  
Shear Flow Instability

The effect of a parallel magnetic field upon the stability of the plane interface between two conducting viscous fluids in uniform relative motion is considered. A parameter reduction, which has not previously been noted, is employed to facilitate the solution of the problem. Neutral stability curves for unrestricted ranges of the governing parameters are found, and the approximate solutions of other authors are examined in this light.

Effects of Inertia and Viscosity on Single Droplet Deformation in Confined Shear Flow

2013 ◽  
Vol 13 (3) ◽  
pp. 706-724 ◽  
Author(s):  
Samaneh Farokhirad ◽  
Taehun Lee ◽  
Jeffrey F. Morris
Keyword(s):  
Reynolds Number ◽  
Shear Flow ◽  
Viscous Fluid ◽  
Lattice Boltzmann ◽  
Viscosity Ratio ◽  
Diffuse Interface ◽  
Single Droplet ◽  
Droplet Deformation ◽  
Droplet Dynamics ◽  
Lattice Boltzmann Simulations

AbstractLattice Boltzmann simulations based on the Cahn-Hilliard diffuse interface approach are performed for droplet dynamics in viscous fluid under shear flow, where the degree of confinement between two parallel walls can play an important role. The effects of viscosity ratio, capillary number, Reynolds number, and confinement ratio on droplet deformation and break-up in moderately and highly confined shear flows are investigated.

Wind-Generated Surface Waves on a Viscous Fluid

1985 ◽  
Vol 52 (1) ◽  
pp. 208-212 ◽  
Author(s):  
C. Katsis ◽  
T. R. Akylas
Keyword(s):  
Shear Flow ◽  
Viscous Fluid ◽  
Surface Waves ◽  
High Viscosity ◽  
Wave Generation ◽  
Generation Mechanism ◽  
Flow Profile ◽  
Wind Speeds ◽  
Dominant Wave ◽  
Tollmien Schlichting

The excitation of surface waves on a viscous fluid by shear flows is studied. Turbulent and laminar air flows over oil of low and high viscosity are considered. It is found that the dominant wave-generation mechanism depends crucially on the shear-flow profile: for a turbulent flow, long surface waves are generated at low wind speeds due to the work done by the stress components in phase with the surface slope, while Kelvin-Helmholtz instability is responsible for the excitation of short waves at higher wind speeds. On the other hand, for a laminar shear flow, direct resonance between surface waves and Tollmien-Schlichting waves in the shear flow is the dominant wave-generation mechanism.

scholarly journals Pulsating Flow of a Viscous Fluid over a Cavity Containing a Compressible Gas Bubble

2021 ◽  
Vol 56 (6) ◽  
pp. 799-811
Author(s):  
A. I. Ageev ◽  
A. N. Osiptsov
Keyword(s):  
Viscous Fluid ◽  
Superhydrophobic Surface ◽  
Numerical Study ◽  
Plane Channel ◽  
Velocity Slip ◽  
Pulsating Flow ◽  
Friction Reduction ◽  
Gas Bubble ◽  
Viscous Boundary Layer ◽  
Compressible Gas

A two-dimensional pulsating flow of a viscous fluid in a plane channel whose wall has rectangular microcavities partially or completely filled with a compressible gas is investigated. This problem formulation can clarify the friction reduction mechanism in a laminar sublayer of a turbulent viscous boundary layer flow over a textured stripped superhydrophobic surface containing periodically arranged rectangular micro-cavities filled with gas. It is assumed that the dimensions of the cavities are much smaller than the channel thickness. On the macroscale, the problem of one-dimensional unsteady viscous flow in a plane channel with no-slip conditions on the walls and a harmonic variation of the pressure difference is solved. The solution obtained in this way is used for formulating non-stationary in time and periodic in space boundary conditions for the flow on the scale of a chosen cavity (microscale), with the instantaneous volume of the gas bubble in the cavity depending on the instantaneous pressure over the cavity. The flow on the microscale near a cavity with a gas bubble occurs in the Stokes regime. The numerical solution is obtained using an original version of the boundary element method. A parametric numerical study of the flow field in a pulsating shear flow over a cavity with a compressible gas bubble is performed. The averaged parameters characterizing the effective ‘velocity slip’ of viscous fluid and the friction reduction in a pulsating flow over a stripped superhydrophobic surface are calculated.

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