scholarly journals Experimental study of the rheology of water-kaolinite suspensions

2021 ◽  
Author(s):  
Zhongfan Zhu
Keyword(s):  
Shear Stress ◽  
Particle Concentration ◽  
Fluid Model ◽  
Dlvo Theory ◽  
Experimental Information ◽  
Sediment Suspension ◽  
Solid Concentration ◽  
Concentration Data ◽  
Fine Grained ◽  
Sediment Particles

Abstract How the added electrolyte condition and size of primary sediment particles, as well as the particle concentration, affect the rheological behaviours of water-sediment suspension remains to be of interest in sediment field. In this work, rheological experiments of water-kaolinite suspensions with different electrolyte conditions, two particle sizes and 39 solid concentrations were performed. The Bingham fluid model has been adopted to fit the experimental data, and the viscosity and Bingham shear stress values were calculated for each suspension. It has been found that an increase in electrolyte concentration and/or valence leads to a larger viscosity value of the suspension, whereas an increase in electrolyte valence yields a smaller Bingham shear stress value. A simple interpretation based on DLVO theory was presented in this study. It has also been observed that a fine-grained kaolinite suspension corresponds to larger suspension viscosity and Bingham shear stress values. Additionally, some experimental information on the viscosity-solid concentration and Bingham shear stress-solid concentration relationships were also presented in this study. For the viscosity-solid concentration data, the Krieger and Dougherty formula provided the best fit, and a simple exponential relation showed a good fit for the measured shear stress-solid concentration data. HIGHLIGHT This manuscript is valuable in terms of studying ow the added electrolyte condition and size of primary sediment particles, as well as the particle concentration, affect the rheological behaviours of water-sediment suspension.

scholarly journals Effects of salinity and particle concentration on sediment hydrodynamics and critical bed-shear-stress for erosion of fine grained sediments used in wetland restoration projects

2015 ◽  
Vol 367 ◽  
pp. 435-441 ◽  
Author(s):  
M. Ghose-Hajra ◽  
A. McCorquodale ◽  
G. Mattson ◽  
D. Jerolleman ◽  
J. Filostrat
Keyword(s):  
Shear Stress ◽  
Mississippi River ◽  
Particle Concentration ◽  
Gulf Coast ◽  
Open Water ◽  
Distribution Model ◽  
Bed Shear Stress ◽  
Sediment Distribution ◽  
Fine Grained ◽  
Term Performance

Abstract. Sea-level rise, the increasing number and intensity of storms, oil and groundwater extraction, and coastal land subsidence are putting people and property at risk along Louisiana’s coast, with major implications for human safety and economic health of coastal areas. A major goal towards re-establishing a healthy and sustainable coastal ecosystem has been to rebuild Louisiana’s disappearing wetlands with fine grained sediments that are dredged or diverted from nearby rivers, channels and lakes to build land in open water areas. A thorough geo-hydrodynamic characterization of the deposited sediments is important in the correct design and a more realistic outcome assessment of the long-term performance measures for ongoing coastal restoration projects. This paper evaluates the effects of salinity and solid particle concentration on the re-suspension characteristics of fine-grained dredged sediments obtained from multiple geographic locations along the Gulf coast. The critical bed-shear-stress for erosion has been evaluated as a function of sedimentation time. The sediment hydrodynamic properties obtained from the laboratory testing were used in a numerical coastal sediment distribution model to aid in evaluating sediment diversions from the Mississippi River into Breton Sound and Barataria Bay.

scholarly journals Analysis of dynamics variation against thixotropic parameter’s preferential range

2018 ◽  
Vol 45 (2) ◽  
pp. 231-251
Author(s):  
Nazish Shahid
Keyword(s):  
Shear Stress ◽  
Pressure Gradient ◽  
Flow Rate ◽  
Axial Velocity ◽  
Fluid Model ◽  
Current Model ◽  
Velocity Shear ◽  
Structural Parameter ◽  
Velocity Flow ◽  
Analysis Of Dynamics

Variation in the dynamics of a steady-state blood flow through a stenosed tapered artery has been investigated corresponding to changes in thixotropic parameter ? over the range [0,1]. To probe the role of parameter ? and differentiate the current model from other known non-Newtonian models, expressions of axial velocity, shear stress, wall shear stress and flow rate have been calculated depending upon this parameter and pressure gradient. Also, pressure gradient has been deduced uniquely with the help of the continuity equation. Our choice of calculating pressure gradient has led to obtaining shear stress such that its dependence on the structural parameter of our model, unlike most available results, motivates for further investigation. The simultaneous effects of varying yield stress and parameter ? on axial velocity, flow resistance and flow rate have been studied such that the differences between the Herschel?Bulkley fluid model and our current model can be pointed out. To validate the suitability of our model and some results in history, we have also obtained limiting results for particular values of ?.

Measuring the onset of mine tailings erosion

2007 ◽  
Vol 44 (4) ◽  
pp. 473-489 ◽  
Author(s):  
M Haneef-Mian ◽  
Ernest K Yanful ◽  
Robert Martinuzzi
Keyword(s):  
Shear Stress ◽  
Power Law ◽  
Mine Tailings ◽  
Laser Doppler Anemometry ◽  
Critical Shear Stress ◽  
Laser Doppler ◽  
Shear Stresses ◽  
Cohesive Sediments ◽  
Fine Grained ◽  
Power Law Equation

The present study gives details of a methodology for estimating the critical shear stress for erosion of mine tailings and other naturally occurring cohesive sediments. Erosion of a cohesive sediments bed occurs when the critical shear stress is exceeded to break the interparticle bond. Experiments were conducted in a 30 cm diameter laboratory column and calibrated using laser Doppler anemometry. The results showed that the erosion pattern of mine tailings particles was similar to those of fine-grained cohesive sediments. A power-law relation of the form E = α[(τ – τcr)/τcr]n is suggested for mine tailings, where E is the erosion rate, α is a coefficient, τ is the shear stress, τcr is the critical shear stress, and n is an exponent. The computed values of α, n, and τcr in the power-law equation were found to be comparable to values derived from experiments in a rotating circular flume. The derived expression for rate of erosion may be incorporated in resuspension and transport models for fine mine tailings of a similar nature.Key words: mine tailings, laser Doppler velocimetry, wall shear stresses, critical shear stress for erosion, erosion – shear stress relationship.

Mathematical analysis of Phan-Thien–Tanner fluid model for blood in arteries

2015 ◽  
Vol 08 (05) ◽  
pp. 1550064
Author(s):  
Noreen Sher Akbar ◽  
S. Nadeem
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Fluid Model ◽  
Shearing Stress ◽  
Small Arteries ◽  
Tapered Artery ◽  
Impedance Wall ◽  
Flow Through ◽  
Parameters Of Interest

In the present paper, we have studied the blood flow through tapered artery with a stenosis. The non-Newtonian nature of blood in small arteries is analyzed mathematically by considering the blood as Phan-Thien–Tanner fluid. The representation for the blood flow is through an axially non-symmetrical but radially symmetric stenosis. Symmetry of the distribution of the wall shearing stress and resistive impedance and their growth with the developing stenosis is another important feature of our analysis. Exact solutions have been evaluated for velocity, resistance impedance, wall shear stress and shearing stress at the stenosis throat. The graphical results of different type of tapered arteries (i.e. converging tapering, diverging tapering, non-tapered artery) have been examined for different parameters of interest.

Computational Analysis on Weld Formation Mechanism during Self-Reacting Friction Stir Welding

2020 ◽  
pp. 1-15
Author(s):  
Chenyu Zhao ◽  
Xun Liu
Keyword(s):  
Boundary Condition ◽  
Shear Stress ◽  
Friction Stir Welding ◽  
Shear Layer ◽  
Formation Mechanism ◽  
Fluid Model ◽  
Three Dimensional ◽  
Welding Process ◽  
Weld Formation ◽  
Friction Stir

Abstract Three-dimensional computational fluid dynamics models are developed to understand physical principles of self-reacting friction stir welding process. A novel approach of predicting the weld microstructure based on plastic strain distribution at cross-section behind the tool is proposed and verified with experimental results. Limitations and credibility of shear stress and velocity tool/workpiece boundary condition are evaluated from the perspective of the weld formation mechanism. The importance of the shear layer and its sticking/sliding transition state in weld formation mechanism is emphasized. From modeling perspective, shear stress boundary, which only represents a sliding condition, neglects the movement and effects of this shear layer. When shear layer is formed, due to the velocity discontinuity which could not be captured in fluid model, velocity boundary condition, which represents an averaging effect of sticking/sliding transition between tool and shear layer, is needed.

Is Radioactive Tank Waste a Bingham Fluid?

2019 ◽  
Author(s):  
Leonard F. Pease ◽  
Arich J. Fuher ◽  
Judith A. Bamberger ◽  
Carolyn A. Burns ◽  
Richard C. Daniel ◽  
...  
Keyword(s):  
Shear Stress ◽  
Yield Stress ◽  
Fluid Model ◽  
Bingham Fluid ◽  
Waste Processing ◽  
Rheological Models ◽  
Cross Model ◽  
Shear Rates ◽  
Sludge Waste ◽  
Tank Waste

Abstract Slurries and sludges across the United States Department of Energy (DOE) complex rank among the most rheologically interesting. Their composition is heterogeneous, spanning a very broad range of particle sizes, densities, and interparticle forces. All exhibit shear thinning, some have yield stresses, and many are thixotropic. Despite the variety, these complex fluids are often represented using the historic Bingham fluid model, which fits higher shear rate data to a simple straight line. The intercept provides a yield stress, which has been a key design parameter in construction of large-scale waste processing facilities. However, many radioactive wastes are simply not Bingham fluids, and this representation extrapolates poorly across low to intermediate shear rates that are characteristic of typical processing conditions. Indeed, processing shear rates as high as 200 1/s, which has been a typical minimum shear rate used in fitting the Bingham fluid model, are seldom encountered in nuclear waste processing. Therefore, more realistic rheological models are necessary to accurately predict waste processing performance. Pacific Northwest National Laboratory (PNNL) recently re-evaluated the rheology of reconstituted Hanford REDOX (reduction-oxidation) process sludge waste against a wide variety of rheological models including the Bingham, Cross, Cross with yield stress, Carreau, biviscous, Herschel-Bulkley (which includes a power law dependence), Casson, and Gay models. They found that all of the models provided a closer fit than the Bingham model and that the biviscous model and Cross with yield stress model were convincing. However, reconstituted Hanford REDOX sludge waste is but one type of DOE waste and a direct contrast, and comparison of these three models against undiluted, unmixed tank waste (actual not simulant) has not been performed previously. Therefore, the purpose of this paper is to evaluate the rheology of actual tank waste with these more accurate rheological models. In this paper, we evaluate select rheological data for slurry samples from Hanford’s AZ-101, AZ-102, and SY-101 waste tanks. In each of these cases, we find that Cross’ model with yield stress and the biviscous model significantly outperform the Bingham fluid model. Furthermore, the AZ-101 data also shows that the shear stress peak at startup significantly exceeds the Bingham yield stress, which is commonly observed in the initial moments of rheological measurements on simulants. Remarkably, Cross’ model may empirically accommodate an initial spike in shear stress at modest shear rates. These are important observations because computational and analytical fluid dynamics simulations rely on rheological constitutive models for accurately and conservatively predicting waste processing performance. These findings suggest the need for better rheological modeling of and validation against radioactive waste.

The LABEREX chamber for studying the critical shear stress for fine-grained sediment

1999 ◽  
Vol 99 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Lars Chresten Lund-Hansen ◽  
Christian Christiansen ◽  
Ole Jensen ◽  
Mario Laima
Keyword(s):  
Shear Stress ◽  
Critical Shear Stress ◽  
Fine Grained

Achievement of Pentoxifylline for Blood Flow through Stenosed Artery

2012 ◽  
Vol 13 ◽  
pp. 81-89
Author(s):  
Sapna Ratan Shah ◽  
S.U. Siddiqui
Keyword(s):  
Blood Flow ◽  
Shear Stress ◽  
Wall Shear Stress ◽  
Apparent Viscosity ◽  
Fluid Model ◽  
Plasma Viscosity ◽  
Diabetic Patients ◽  
Newtonian Viscosity ◽  
Stenosed Artery ◽  
Wall Shear

Blood-viscosity reducing drugs like “Pentoxifylline” improve blood flow by making the blood less viscous. The resistance to flow of blood in diabetic patients is higher than in non-diabetic patients. Thus diabetic patients with higher resistance to flow are more prone to high blood pressure. Therefore the resistance to blood flow in case of diabetic patients may be reduced by reducing viscosity of the plasma. Viscosity of plasma can be reducing by giving Pentoxifylline. In this paper an attempt has been made to investigate the blood flow behaviour and significance of non-Newtonian viscosity through a stenosed artery using Bingham Plastic fluid model. Numerical illustrations presented at the end of the paper provide the results for the resistance to flow, apparent viscosity and the wall shear stress through their graphical representations. It has been shown that the resistance to flow, apparent viscosity and wall shear stress increases with the size of the stenosis but these increases are comparatively small due to non-Newtonian behaviour of the blood indicating the usefulness of its rheological character in the functioning of the diseased arterial circulation.

Development of a Transient Mechanistic Two-Phase Flow Model for Wellbores

SPE Journal ◽  
2012 ◽  
Vol 17 (03) ◽  
pp. 942-955 ◽  
Author(s):  
Mahdy Shirdel ◽  
Kamy Sepehrnoori
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Two Phase Flow ◽  
Fluid Model ◽  
Flow Regimes ◽  
Phase Flow ◽  
Two Phase ◽  
Wall Shear ◽  
Two Fluid Model ◽  
Two Fluid

Summary A great deal of research has been focused on transient two-phase flow in wellbores. However, there is lack of a comprehensive two-fluid model in the literature. In this paper, we present an implementation of a pseudo-compositional, thermal, fully implicit, transient two-fluid model for two-phase flow in wellbores. In this model, we solve gas/liquid mass balance, gas/liquid momentum balance, and two-phase energy balance equations to obtain five primary variables: liquid velocity, gas velocity, pressure, holdup, and temperature. This simulator can be used as a stand-alone code or can be used in conjunction with a reservoir simulator to mimic wellbore/reservoir dynamic interactions. In our model, we consider stratified, bubbly, intermittent, and annular flow regimes using appropriate closure relations for interphase and wall-shear stress terms in the momentum equations. In our simulation, we found that the interphase and wall-shear stress terms for different flow regimes can significantly affect the model's results. In addition, the interphase momentum transfer terms mainly influence the holdup value. The outcome of this research leads to a more accurate simulation of multiphase flow in the wellbore and pipes, which can be applied to the surface facility design, well-performance optimization, and wellbore damage estimation.

scholarly journals The Influence of Magnetohydrodynamic Flow and Slip Condition on Generalized Burgers’ Fluid with Fractional Derivative

2020 ◽  
Vol 17 (1) ◽  
pp. 0150
Author(s):  
Nassief Et al.
Keyword(s):  
Shear Stress ◽  
Fractional Calculus ◽  
Fractional Derivative ◽  
Velocity Distribution ◽  
Constant Pressure ◽  
Fluid Model ◽  
Magnetohydrodynamic Flow ◽  
Slip Condition ◽  
Constitutive Relationship ◽  
Burgers Fluid

This paper investigates the effect of magnetohydrodynamic (MHD) of an incompressible generalized burgers’ fluid including a gradient constant pressure and an exponentially accelerate plate where no slip hypothesis between the burgers’ fluid and an exponential plate is no longer valid. The constitutive relationship can establish of the fluid model process by fractional calculus, by using Laplace and Finite Fourier sine transforms. We obtain a solution for shear stress and velocity distribution. Furthermore, 3D figures are drawn to exhibit the effect of magneto hydrodynamic and different parameters for the velocity distribution.

Sign in / Sign up

Export Citation Format

Share Document