Numerical Study on Gas-Yield Power-Law Fluid in T-Junction Minichannel

2019 ◽  
Author(s):  
Abdalsalam Ihmoudah ◽  
Mohamed M. Awad ◽  
Aziz Rahman ◽  
Stephen D. Butt
Keyword(s):  
Film Thickness ◽  
Power Law ◽  
Xanthan Gum ◽  
Numerical Study ◽  
Superficial Velocity ◽  
Bubble Velocity ◽  
Two Phase ◽  
Ansys Fluent ◽  
Power Law Fluids ◽  
Taylor Bubbles

Abstract In this study, a computational examination of Taylor bubbles was performed for gas/non-Newtonian fluid two-phase flows developed in a minichannel T-junction mixer with a hydraulic diameter of 1 mm. The investigations employed three separate aqueous xanthan gum solutions at concentrations of 0.05, 0.1 and 0.15 w/w, which are referred to as non-Newtonian (yield power-law) fluids. The effective concentration of the xanthan gum solutions and superficial velocity of the inlet liquid phase on the length, velocity, and shape of the Taylor bubbles was studied using the ANSYS FLUENT 19 software package. The simulation results show an increase in bubble velocity with increasing film thickness, particularly in solutions of higher viscosity XG-0.15%. Furthermore, bubble lengths decreased as the xanthan gum concentrations increased, but bubble shapes underwent alterations when the concentrations increased. Another interesting result of the tests shows that when the liquid inlet velocity increases, bubble lengths decrease during lower liquid superficial velocity, whereas during higher velocities, they change only slightly after increases in concentration. Finally, with increasing XG concentration, the liquid film thickness around the bubble increased. The results show good agreement with correlations after modifying a capillary number (Ca*) for non-Newtonian liquids in all cases.

Experimental and Numerical Investigation of Gas-Yield Power-Law Fluids in a Horizontal Pipe

2019 ◽  
Author(s):  
Abdalsalam Ihmoudah ◽  
Mohamed M. Awad ◽  
Mohammad Azizur Rahman ◽  
Stephen D. Butt
Keyword(s):  
Power Law ◽  
Two Phase Flow ◽  
Operating Conditions ◽  
Superficial Velocity ◽  
Rheological Parameters ◽  
Phase Flow ◽  
Two Phase ◽  
Horizontal Pipe ◽  
Power Law Fluids ◽  
Wide Range

Abstract Two-phase flow of gas/yield power-law (YPL) fluids in pipes can be found in a wide range of practical and industrial applications. To improve the understanding of the effects of rheological parameters of non-Newtonian liquids in a two-phase model, experimental and Computational Fluid Dynamics (CFD) investigations of gas/yield power-law fluids in a horizontal pipe were carried out. Two Xanthan gum (XG) solutions at concentrations of (0.05% and 0.10% by weight) were used as the working liquids. The experiments were conducted in a flow loop in a 65-m open-cycle system. The horizontal test section had a diameter of 3 inches (76.2 mm). The transient calculations were conducted using a Volume of Fluid (VOF) model in ANSYS Fluent version 17.2. Slug flow characteristics were recorded and observed by a high-speed digital camera in different operating conditions. The slug velocity and slug frequency were investigated experimentally and numerically, and a comparison of results with empirical relationships found in the literature was performed. We observed that the rheological properties of non-Newtonian phase influence the flow behavior in two-phase flow with increasing XG concentrations. The results of the empirical correlation to measure the slug frequency of a gas/non-Newtonian with considered the rheology of the shear-thinning behaver gave acceptable agreement with numerical measurements at low polymer concentration. The effect of liquid superficial velocity on slug translational velocity at low gas superficial velocity was relatively high.

scholarly journals Numerical Study on the Tandem Submerged Hydrofoils Using RANS Solver

2021 ◽  
Vol 2021 ◽  
pp. 1-17
Author(s):  
Moloud Arian Maram ◽  
Hamid Reza Ghafari ◽  
Hassan Ghassemi ◽  
Mahmoud Ghiasi
Keyword(s):  
Drag Coefficient ◽  
Single Phase ◽  
Two Phase Flow ◽  
Numerical Study ◽  
Lift Coefficient ◽  
Lower Surface ◽  
Phase Flow ◽  
Two Phase ◽  
Hydrodynamic Coefficient ◽  
Ansys Fluent

This paper is presented on the tandem two-dimensional hydrofoils with profiles NACA4412 in single-phase and two-phase flow domains for different submergence depths and different distances in a various angle of attack (AoA). Also, supercavitation is studied at σ = 0.34 by the Zwart cavitation model. Reynolds-averaged Navier–Stokes (RANS) with the shear stress transport (SST) K-ω is employed as a turbulence model in transient analysis of Ansys FLUENT software. The numerical results show that, by increasing depth, the drag coefficient increases for both hydrofoils 1 and 2 as well as the lift coefficient. The drag coefficient of hydrofoil 2 is bigger than hydrofoil 1 for all depths; moreover, it was found that the flow pressure behind the hydrofoil 1 had affected the upper and the lower surface of the hydrofoil 2 at each distance or AoA. These effects are observed in the hydrofoil 2 lift coefficient as well as the flow separation. However, the maximum lift-to-drag ratio is observed at AoA =  8 ° and 3.5c distance. Also, single-phase results reveal that the value of pressure and the hydrodynamic coefficient are very different from the two-phase flow results, due to the elimination of the free surface. So, a two-phase flow domain is recommended for increasing the accuracy of results. In addition, the investigation of supercavitation shows a growth in cavity occurrence on the surface by raising AoA.

scholarly journals Finite Volume Simulation of Natural Convection for Power-Law Fluids with Temperature-Dependent Viscosity in a Square Cavity with a Localized Heat Source

2021 ◽  
Vol 39 (5) ◽  
pp. 1405-1416
Author(s):  
Hamza Daghab ◽  
Mourad Kaddiri ◽  
Said Raghay ◽  
Ismail Arroub ◽  
Mohamed Lamsaadi ◽  
...  
Keyword(s):  
Natural Convection ◽  
Heat Source ◽  
Finite Volume ◽  
Power Law ◽  
Numerical Study ◽  
Staggered Grid ◽  
Cooling Performance ◽  
Coupled Equations ◽  
Power Law Fluids ◽  
Power Law Index

In this paper, numerical study on natural convection heat transfer for confined thermo-dependent power-law fluids is conducted. The geometry of interest is a fluid-filled square enclosure where a uniform flux heating element embedded on its lower wall is cooled from the vertical walls while the remaining parts of the cavity are insulated, without slipping conditions at all the solid boundaries. The governing partial differential equations written in terms of non-dimensional velocities, pressure and temperature formulation with the corresponding boundary conditions are discretized using a finite volume method in a staggered grid system. Coupled equations of conservation are solved through iterative Semi Implicit Method for Pressure Linked Equation (SIMPLE) algorithm. The effects of pertinent parameters, which are Rayleigh number (103 ≤ Ra ≤ 106), power-law index (0.6 ≤ n ≤ 1.4), Pearson number (0 ≤ m ≤ 20) and length of the heat source (0.2 ≤ W ≤ 0.8) on the cooling performance are investigated. The results indicate that the cooling performance of the enclosure is improved with increasing Pearson and Rayleigh numbers as well as with decreasing power-law index and heat source length.

An Accurate Model for Prediction of Turbulent Frictional Pressure Loss of Power-Law Fluids in Eccentric Geometries

2021 ◽  
pp. 1-18
Author(s):  
Vahid Dokhani ◽  
Yue Ma ◽  
Zili Li ◽  
Mengjiao Yu
Keyword(s):  
Power Law ◽  
Pressure Loss ◽  
Eddy Viscosity ◽  
Numerical Study ◽  
Axial Flow ◽  
Drilling Fluids ◽  
Eddy Viscosity Model ◽  
Friction Factors ◽  
Power Law Fluids ◽  
Eccentric Annuli

Summary The effect of axial flow of power-law drilling fluids on frictional pressure loss under turbulent conditions in eccentric annuli is investigated. A numerical model is developed to simulate the flow of Newtonian and power-law fluids for eccentric annular geometries. A turbulent eddy-viscosity model based on the mixing-length approach is proposed, where a damping constant as a function of flow parameters is presented to account for the near-wall effects. Numerical results including the velocity profile, eddy viscosity, and friction factors are compared with various sets of experimental data for Newtonian and power-law fluids in concentric and eccentric annular configurations with diameter ratios of 0.2 to 0.8. The simulation results are also compared with a numerical study and two approximate models in the literature. The results of extensive simulation scenarios are used to obtain a novel correlation for estimation of the frictional pressure loss in eccentric annuli under turbulent conditions. Two new correlations are also presented to estimate the maximum axial velocity in the wide and narrow sections of eccentric geometries.

CFD and Experimental Studies of Yield Power-Law Fluids in Turbulent Pipe Flow

2018 ◽  
Author(s):  
Abdalsalam Ihmoudah ◽  
M. A. Rahman ◽  
Stephen D. Butt
Keyword(s):  
Turbulent Flow ◽  
Power Law ◽  
Pressure Loss ◽  
Xanthan Gum ◽  
Newtonian Fluids ◽  
Turbulent Pipe Flow ◽  
Flow Loop ◽  
Horizontal Pipe ◽  
Cfd Models ◽  
Power Law Fluids

The transport of Non-Newtonian fluids through pipelines and mud circulation in wellbores often occur in turbulent flow regimes. In this study, experiments and computational fluid dynamics (CFD) models are used to examine the influence of yield power law (YPL) fluid rheological properties on pressure loss in the flow loop in turbulent flow. Three Non-Newtonian fluids at different concentrations of Xanthan gum solutions (0.05%, 0.10% and 0.15%, by weight) are studied at flow rates ranging between 400 and 800 L/min. A fully instrumented flow loop system was used, consisting of three main sections of different inclinations: 5 m long horizontal, 5 m vertical, and 3 m inclined 45° test section. Additionally, CFD codes of ANSYS CFX 17.2 are examined and compared to experimental results. These models are based on the Reynolds Averaged Navier-Stokes (RANS) equations. The comparison is done with the results of these investigations, based on vertical and horizontal pipe frictional pressure drops. The results show that the gap between experimental and CFD models has been increased in comparison with increase concentration Xanthan gum solution at the same density of fluids. Specifically, pressure loss rises with rises in the consistency index, k and flow behaviour index, However, rises in yield stress τ0 showed less impacts on frictional pressure losses. Given these simulation outcomes, it is clear that pressure drop in the Non-Newtonian fluid in one phase flow can be more accurately predicted by used the Reynolds-Stress Models (RSM) more than Eddy-viscosity models.

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