Prediction of holdup, axial pressure gradient and wall shear stress in wavy stratified and stratified/atomization gas/liquid flow

1999 ◽  
Vol 25 (2) ◽  
pp. 365-376 ◽  
Author(s):  
N.A. Vlachos ◽  
S.V. Paras ◽  
A.J. Karabelas
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pressure Gradient ◽  
Liquid Flow ◽  
Axial Pressure ◽  
Axial Pressure Gradient ◽  
Wall Shear ◽  
Gas Liquid Flow

scholarly journals Hydrodynamic structure of the flow around a stationary gas bubble in an annular channel

2021 ◽  
Vol 2057 (1) ◽  
pp. 012036
Author(s):  
O N Kashinsky ◽  
A S Kurdyumov
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Liquid Flow ◽  
Liquid Velocity ◽  
Capillary Tube ◽  
Annular Channel ◽  
Gas Bubble ◽  
Wall Shear ◽  
Gas Liquid Flow ◽  
Stationary Bubble

Abstract Characteristics of the slug gas liquid flow in an annular channel were studied experimentally. The channel had the diameters of outer and inner tubes of 32 and 10 mm. The liquid flow was downward. The stationary bubble (gas slug) was produced by injecting air through a capillary tube. Wall shear stress measurements were performed by electrodiffusional technique. The measured circumferential distributions of wall shear stress demonstrated a strong non-uniformity across the channel. The highest liquid velocity was in the region of bridge streamining the bubble. The highest values of wall shear stress fluctuations are in the transition region between gas bubble and liquid bridge.

On the Use of the Preston Tube in Concentric Annuli

1967 ◽  
Vol 71 (684) ◽  
pp. 865-865
Author(s):  
H. G. Lyall
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Outer Wall ◽  
Technical Note ◽  
Shear Stresses ◽  
Wall Region ◽  
Axial Pressure ◽  
Valid Conclusion ◽  
Axial Pressure Gradient ◽  
Wall Shear

In his technical note in the January 1967 JOURNAL, Quarmby (pp 47-49) concludes that because he was able to predict the axial pressure gradient in a concentric smooth annulus by using Preston tubes to measure the inner and outer wall shear stress, then the Preston tubes are giving correct values for the wall shear stresses. I cannot agree that this is a valid conclusion to draw. A Preston tube can only give wall shear stress correctly if the dimensionless velocity in the wall region is the same as that for which the tube was calibrated.

A Superposition Analysis of the Turbulent Boundary Layer in an Adverse Pressure Gradient

1951 ◽  
Vol 18 (1) ◽  
pp. 95-100
Author(s):  
Donald Ross ◽  
J. M. Robertson
Keyword(s):  
Boundary Layer ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Turbulent Boundary Layer ◽  
Velocity Profile ◽  
Pressure Gradient ◽  
Adverse Pressure Gradient ◽  
Pressure Recovery ◽  
Stress Coefficient ◽  
Wall Shear

Abstract As an interim solution to the problem of the turbulent boundary layer in an adverse pressure gradient, a super-position method of analysis has been developed. In this method, the velocity profile is considered to be the result of two effects: the wall shear stress and the pressure recovery. These are superimposed, yielding an expression for the velocity profiles which approximate measured distributions. The theory also leads to a more reasonable expression for the wall shear-stress coefficient.

scholarly journals Biorheological Model on Flow of Herschel-Bulkley Fluid through a Tapered Arterial Stenosis with Dilatation

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
S. Priyadharshini ◽  
R. Ponalagusamy
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Pressure Gradient ◽  
Power Law ◽  
Flow Resistance ◽  
Velocity Profiles ◽  
Arterial Stenosis ◽  
Axial Distance ◽  
Tapered Artery ◽  
Wall Shear

An analysis of blood flow through a tapered artery with stenosis and dilatation has been carried out where the blood is treated as incompressible Herschel-Bulkley fluid. A comparison between numerical values and analytical values of pressure gradient at the midpoint of stenotic region shows that the analytical expression for pressure gradient works well for the values of yield stress till 2.4. The wall shear stress and flow resistance increase significantly with axial distance and the increase is more in the case of converging tapered artery. A comparison study of velocity profiles, wall shear stress, and flow resistance for Newtonian, power law, Bingham-plastic, and Herschel-Bulkley fluids shows that the variation is greater for Herschel-Bulkley fluid than the other fluids. The obtained velocity profiles have been compared with the experimental data and it is observed that blood behaves like a Herschel-Bulkley fluid rather than power law, Bingham, and Newtonian fluids. It is observed that, in the case of a tapered stenosed tube, the streamline pattern follows a convex pattern when we move fromr/R=0tor/R=1and it follows a concave pattern when we move fromr/R=0tor/R=-1. Further, it is of opposite behaviour in the case of a tapered dilatation tube which forms new information that is, for the first time, added to the literature.

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