Flow pattern transition, pressure gradient, hold-up predictions in gas/non-Newtonian power-law fluid stratified flow

2014 ◽  
Vol 63 ◽  
pp. 105-115 ◽  
Author(s):  
Davide Picchi ◽  
Sebastiano Correra ◽  
Pietro Poesio
Keyword(s):  
Pressure Gradient ◽  
Flow Pattern ◽  
Power Law ◽  
Stratified Flow ◽  
Power Law Fluid ◽  
Transition Pressure ◽  
Flow Pattern Transition

Dimensionless oil-water stratified to non-stratified flow pattern transition

2017 ◽  
Vol 151 ◽  
pp. 284-291 ◽  
Author(s):  
A. Al-Sarkhi ◽  
E. Pereyra ◽  
I. Mantilla ◽  
C. Avila
Keyword(s):  
Flow Pattern ◽  
Stratified Flow ◽  
Flow Pattern Transition ◽  
Oil Water

scholarly journals Peristaltic Transport of Power-Law Fluid in an Elastic Tapered Tube with Variable Cross-Section Induced by Dilating Peristaltic Wave

2021 ◽  
pp. 1293-1306
Author(s):  
Mohammed Ali Murad ◽  
Ahmed M. Abdulhadi
Keyword(s):  
Pressure Gradient ◽  
Cross Section ◽  
Power Law ◽  
Variable Cross Section ◽  
Peristaltic Transport ◽  
Peristaltic Wave ◽  
Variable Cross ◽  
Power Law Fluid ◽  
Opposite Behavior ◽  
Local Shear

The peristaltic transport of power-law fluid in an elastic tapered tube with variable cross-section induced by dilating peristaltic wave is studied. The exact solution of the expression for axial velocity, radial velocity, stream function, local shear stress, volume of flow rate and pressure gradient are obtained under the assumption of long wavelength and low Reynolds number. The effects of all parameters that appear in the problem are analyzed through graphs. The results showed that the flux is sinusoidal in nature and it is an increasing function with the increase of  whereas it is a decreasing function with the increase of . An opposite behavior for shear strain is noticed compared to pressure gradient.  Finally, trapping phenomenon is presented to explain the physical behavior of various parameters. It is noted that the size of the trapping bolus increases with increasing  whereas it decreases as  increases. MATHEMATICA software is used to plot all figures.

A CFD Study of the Flow of a Power-Law Fluid in Annuli With Variable Eccentricity

2006 ◽  
Author(s):  
Oswaldo Nun˜ez ◽  
Armando J. Blanco
Keyword(s):  
Shear Stress ◽  
Pressure Gradient ◽  
Flow Pattern ◽  
Power Law ◽  
Numerical Solutions ◽  
Oil Industry ◽  
Flow Patterns ◽  
Rheological Parameters ◽  
Annular Space ◽  
Industrial Processing

Some industrials processes are associated with flow of non-Newtonian fluids in annular spaces. Examples are found in oil industry and food industrial processing. In some cases, gravitational forces cause internal pipe deflection and, consequently, the eccentricity changes along of axis of the annular space. So, flow patterns are modified respect to those found in constant eccentricity annular spaces. Current industrial practice consists on extrapolate predictions based on flow patterns from the constant eccentricity critical scenario, corresponding to the critical region where both boundaries are closer, to the variable eccentricity actual scenario. In practice, using this approach, flow pattern predictions could significantly deviate from the actual profile, and variables such as shear stress at walls or pressure gradient could not be estimated with adequate accuracy. This work consists of a Computational Fluid Dynamics study, aimed to state the implications of evaluating flow patterns, assuming constant eccentricity, in opposition to a more realistic scenario, considering deflection path along the annular space, using a commercial code. A particular application is made to mud removal during well cementing operations in oil industry. For the casing in the hole, the deflection equation is solved and eccentricity along of the system axis is found. Flow of a non-Newtonian fluid described by Power Law model is considered. Oil industry typical conditions are considered for fluid density, rheological parameters, flow rates, casing and hole sizes, and annulus eccentricity. The flow regime was considered laminar. Numerical model capability to reproduce accurately flow patterns in these conditions was assured by comparison with others analytical-numerical solutions for concentric systems. Results show that local Reynolds number Re, shear stress τw and pressure gradient predictions G, under local eccentricity variations, differ from those under constant eccentricity. Differences in Re and τw show a maximum for eccentricity ranging from 60% to 80%, for all flow conditions whereas for G, this difference increases as casing deflection does it. When variable eccentricity models are compared to constant eccentricity one, the latter approach underestimates Re and τw along the narrowest section of the annuli, whereas overestimates the same features along the widest clearance. Additionally, considerably higher variations between these two models are taking place along the narrowest section compared to the variations arising on the widest annular section. When applied to well cementing processes, these results show that considering the most realistic scenario may impact significantly the flow pattern prediction on the annulus during primary cementing operations. Therefore, the quality of the cement job may be greatly compromised.

Study on the Effects of Different Water-Cement Ratios on the Flow Pattern Properties of Cement Grouts

2011 ◽  
Vol 71-78 ◽  
pp. 1264-1267 ◽  
Author(s):  
Zhi Quan Yang ◽  
Ke Peng Hou ◽  
Ting Ting Guo
Keyword(s):  
Flow Pattern ◽  
Newtonian Fluid ◽  
Power Law ◽  
Inflection Point ◽  
Bingham Fluid ◽  
Power Law Fluid ◽  
Conversion Point ◽  
Cement Grouts ◽  
Engineering Practices ◽  
Negative Factors

The article presents an study on the rheological properties of cement grouts with different water-cement ratios of 0.5,0.55,0.6,0.65,0.7,0.75,0.8,0.9,1.0,1.1,1.25,1.0,2.0,5.0 and10.0.It was to investigate different water-cement ratios of cement grouts effecting its flow pattern properties, and thus determinate the conversion point of them among Newtonian fluid, Bingham fluid and Power-law fluid. It confirmed that,when take into accounts of all negative factors possibly affecting the experiment, including asynchronous loading steps, water temperature, apparatus deflection and so on, W/C(water-cement ratio) = 0.75 is a inflection point,which Power-law fluid converted into Bingham fluid, while at W/C =1.25 the cement grouts suffered a conversion from Newtonian fluid to Bingham fluid. This research results supplied, improved and expanded the knowledge of the flow pattern properties of cement grouts and conversion condition with different water-cement ratios, and so it has important theory meaning and realistic value and may contributes to the engineering practices.

Analysis of Lubrication Theory for the Power Law Fluid

1993 ◽  
Vol 115 (1) ◽  
pp. 71-77 ◽  
Author(s):  
M. W. Johnson ◽  
S. Mangkoesoebroto
Keyword(s):  
Thin Film ◽  
Pressure Gradient ◽  
Power Law ◽  
Arbitrary Shape ◽  
Three Dimensional ◽  
Lubrication Theory ◽  
Slider Bearing ◽  
Power Law Fluid ◽  
Rigid Walls ◽  
Working Out

A lubrication theory for the power law fluid is developed and analyzed. Only the infinite width gap is considered. Considered is flow between rigid walls of arbitrary shape under combined Couette and squeezing motion with a pressure gradient. Equations appropriate to a thin film are derived by asymptotic integration of the three-dimensional equations of fluid mechanics. Further integration of these equations yields an algebraic equation for the pressure gradient. Working out the details of the structure of this equation enables us to develop a numerical algorithm for its solution. To illustrate the theory, it is used to calculate the pressure distribution for a parabolic slider bearing and the pressure gradient and velocity distribution when the mass flux is prescribed. The latter results are compared with results obtained earlier by Dien and Elrod (1983).

Frictional Pressure Drops of Two-Phase R-134A Flow in Horizontal and Vertical U-Type Wavy and Straight Tubes

2006 ◽  
Author(s):  
Ing Youn Chen ◽  
Yu-Shi Wu ◽  
Yu-Juei Chang ◽  
Chi-Chuan Wang
Keyword(s):  
Pressure Gradient ◽  
Flow Pattern ◽  
Straight Tube ◽  
Two Phase ◽  
Pressure Drops ◽  
Flow Pattern Transition ◽  
The Difference ◽  
R 134A ◽  
Gradient Ratio ◽  
Phase Pressure

This study presents the measurements of R-134a two-phase frictional pressure gradient subject to vertical and horizontal arrangements of a U-type wavy tube with inner diameter of 5.07 mm and a curvature ratio of 5. The ratio between two-phase pressure gradients of U-bend and straight tube is about 2.5 - 3.5. For the straight tube, the frictional two-phase pressure gradient ratio between the vertical and horizontal arrangements is marginally higher (1.0 - 1.2) for annular flow pattern at x > 0.5, and is 1.0 - 1.4 for the U-bend in the wavy tube. The higher resistance in the vertical arrangement is due to the buoyancy force against the flow inertia. However, for x < 0.5, this ratio is gradually increased due to the difference of flow pattern. The ratio is increased to 1.8 in the straight tube. For the U-bend, the ratio is 2.1 for flow entering the upper tube and is 1.5 for flow entering the lower tube at x = 0.1 and G = 200 kg/m2·s. For the vertical wavy tube, additional effects like the flow pattern transition, liquid flow reversal, and freezing slug may cause additional pressure drops.

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