scholarly journals Numerical process simulation for extrusion using correlated stochastic shear viscosity data

2020 ◽  
Author(s):  
F. Desplentere ◽  
W. Six ◽  
S. Deceur
Keyword(s):  
Shear Viscosity ◽  
Process Simulation ◽  
Viscosity Data ◽  
Numerical Process

scholarly journals Universality of steady shear flow of Rouse melts

2020 ◽  
Vol 59 (10) ◽  
pp. 755-763 ◽  
Author(s):  
Leslie Poh ◽  
Esmaeil Narimissa ◽  
Manfred H. Wagner
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Stress Relaxation ◽  
Shear Flow ◽  
Normal Stress ◽  
Shear Viscosity ◽  
Viscosity Data ◽  
Stress Growth ◽  
Model Predictions

Abstract The data set of steady and transient shear data reported by Santangelo and Roland Journal of Rheology 45: 583–594, (2001) in the nonlinear range of shear rates of an unentangled polystyrene melt PS13K with a molar mass of 13.7 kDa is analysed by using the single integral constitutive equation approach developed by Narimissa and Wagner Journal of Rheology 64:129–140, (2020) for elongational and shear flow of Rouse melts. We compare model predictions with the steady-state, stress growth, and stress relaxation data after start-up shear flows. In characterising the linear-viscoelastic relaxation behaviour, we consider that in the vicinity of the glass transition temperature, Rouse modes and glassy modes are inseparable, and we model the terminal regime of PS13K by effective Rouse modes. Excellent agreement is achieved between model predictions and shear viscosity data, and good agreement with first normal stress coefficient data. In particular, the shear viscosity data of PS13K as well as of two polystyrene melts with M = 10.5 kDa and M = 9.8 kDa investigated by Stratton Macromolecules 5 (3): 304–310, (1972) agree quantitatively with the universal mastercurve predicted by Narimissa and Wagner for unentangled melts, and approach a scaling of Wi−1/2at sufficiently high Weissenberg numbers Wi. Some deviations between model predictions and data are seen for stress growth and stress relaxation of shear stress and first normal stress difference, which may be attributed to limitations of the experimental data, and may also indicate limitations of the model due to the complex interactions of Rouse modes and glassy modes in the vicinity of the glass transition temperature. Graphical abstract

The Measurement of Viscosity of Liquids Under Tension

2003 ◽  
Vol 125 (2) ◽  
pp. 260-266 ◽  
Author(s):  
Peter A. Kottke ◽  
Scott S. Bair ◽  
Ward O. Winer
Keyword(s):  
Shear Viscosity ◽  
Initial Pressure ◽  
Viscosity Coefficient ◽  
Absolute Zero ◽  
Viscosity Data ◽  
Hydrostatic Tension ◽  
Low Shear Viscosity ◽  
Low Shear

The rheological significance of a state of hydrostatic tension was investigated. A method for measuring the limiting low shear viscosity of liquids under tension was developed. The ability of nine liquids to withstand tension was verified, and the magnitudes of tension achievable through different methods were compared. The use of viscosity data from liquids under tension to more accurately determine the initial pressure viscosity coefficient was investigated. The continuity of the pressure viscosity coefficient across absolute zero pressure was verified.

Recalculation of the friction constant and transport coefficients of liquid argon from the Rice-Allnatt theory

1971 ◽  
Vol 24 (2) ◽  
pp. 225 ◽  
Author(s):  
AF Collings ◽  
LA Woolf
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Distribution Function ◽  
Shear Viscosity ◽  
Transport Coefficients ◽  
Liquid Argon ◽  
Viscosity Data ◽  
Liquid Region ◽  
Linear Trajectory ◽  
Momentum And Heat Transfer

The linear trajectory approximation of the ?soft? friction constant in the Rice-Allnatt theory of transport has been computed with specific attention to the lower limit of the integral. The results are significantly different from the Palyvos-Davis values for ζS in the dense gas region but agree within 2% in the liquid region. The Rice- Allnatt expressions for the coefficients of shear viscosity and thermal conductivity have been simplified and a correction of a numerical error in the collisional contributions to momentum and heat transfer is made. The coefficients D, η, and λ have been calculated for the corrected ζS and related expressions. No significant change in D is obtained, but a worsening of agreement with experimental viscosities and thermal conductivities occurs. Conversely, a better prediction of the ratio mλ/kη is obtained. More recent viscosity data for liquid argon indicate the theory is less satisfactory than has previously been considered. These results suggest that any improvement of this class of theory can only come through the use of a better representation of the radial distribution function.

scholarly journals Calculation of the Effective Macromolecular Radii of Human Serum Albumin from the Shear Viscosity Data for Its Aqueous Solutions

2019 ◽  
Vol 64 (4) ◽  
pp. 287 ◽  
Author(s):  
O. V. Khorolskyi
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Aqueous Solutions ◽  
Human Serum ◽  
Shear Viscosity ◽  
Effective Radius ◽  
Water Molecules ◽  
Viscosity Data ◽  
Molecular Radius

The Malomuzh–Orlov theory is used to analyze the experimental shear viscosity data obtained for aqueous solutions of human serum albumin (HSA) at pH = 7.0 in wide temperature and concentration intervals, which allowed the effective radii of HSA macromolecules to be calculated. It is shown that three intervals of the effective molecular radius of HSA with different behaviors can be distinguished in a temperature interval of 278–318 K: 1) below the crossover concentration, the effective molecular radius of HSA remains constant; 2) in the interval from the crossover concentration to about 10 wt%, the effective molecular radius of HSA in the aqueous solution nonlinearly decreases; and 3) at concentrations of 10.2–23.8 wt%, the effective radius of HSA macromolecules linearly decreases, as the concentration grows. The assumption is made that the properties of water molecules in the solution bulk play a crucial role in the dynamics of HSA macromolecules at the vital concentrations of HSA in the solutions. The role of water near the surface of HSA macromolecules and the corresponding changes of its physical properties have been discussed.

Prediction of High-Pressure/High-Temperature Rheological Properties of Drilling Fluids from the Viscosity Data Measured on a Coaxial Cylinder Viscometer

SPE Journal ◽  
2021 ◽  
pp. 1-22
Author(s):  
Sidharth Gautam ◽  
Chandan Guria ◽  
Laldeep Gope
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Shear Viscosity ◽  
Drilling Fluid ◽  
Viscosity Model ◽  
Drilling Fluids ◽  
Viscosity Data ◽  
Monitoring And Control ◽  
High Pressure High Temperature ◽  
Proposed Model

Summary Determining the rheology of drilling fluid under subsurface conditions—that is, pressure > 103.4 MPa (15,000 psi) and temperature > 450 K (350°F)—is very important for safe and trouble-free drilling operations of high-pressure/high-temperature (HP/HT) wells. As the severity of HP/HT wells increases, it is challenging to measure downhole rheology accurately. In the absence of rheology measurement tools under HP/HT conditions, it is essential to develop an accurate rheological model under extreme conditions. In this study, temperature- and pressure-dependence rheology of drilling fluids [i.e., shear viscosity, apparent viscosity (AV), and plastic viscosity (PV)] are predicted at HP/HT conditions using the fundamental momentum transport mechanism (i.e., kinetic theory) of liquids. Drilling fluid properties (e.g., density, thermal decomposition temperature, and isothermal compressibility), and Fann® 35 Viscometer (Fann Instrument Corporation, Houston, USA) readings at surface conditions, are the only input parameters for the proposed HP/HT shear viscosity model. The proposed model has been tested using 26 different types of HP/HT drilling fluids, including water, formate, oil, and synthetic oil as base fluids. The detailed error and the sensitivity analysis have been performed to demonstrate the accuracy of the proposed model and yield comparative results. The proposed model is quite simple and may be applied to accurately predict the rheology of numerous drilling fluids. In the absence of subsurface rheology under HP/HT conditions, the proposed viscosity model may be used as a reliable soft-sensor tool for the online monitoring and control of rheology under downhole conditions while drilling HP/HT wells.

Design for Injection Molding: Using Dimensional Analysis to Assess Fillability

1994 ◽  
Author(s):  
Douglas C. Mehl ◽  
Kurt A. Beiter ◽  
Kos Ishii
Keyword(s):  
Dimensional Analysis ◽  
Process Simulation ◽  
Design Guidelines ◽  
Experimental Program ◽  
Flow Length ◽  
Numerical Process ◽  
Injection Molded ◽  
Plastic Parts ◽  
Injection Molded Plastic

Abstract This paper addresses the determination of wall thicknesses and gating schemes in the preliminary design of injection-molded plastic parts. Today, most of the existing design guidelines come in the form of experience-based qualitative rules. If the designers already have a detailed geometry of the part, the numerical process simulation program provides another form of design aid. There exists a huge gap between these two types of design aids; the experience-based guidelines are often too vague, while the process simulation programs come too late to impact preliminary part design. To fill this gap, this paper develops physics-based guidelines that utilize dimensional analysis techniques. Experiments and simulation studies can deduce non-dimensional relationships between flow length, thickness, material, and process parameters. The guidelines will aid plastic component designers in determining wall-thickness, gating schemes, and in selecting the material in the preliminary stages of part design. This paper describes the formulation of the non-dimensional charts for fillability assessment, and explains the use of these charts in part design. We further outline an ongoing experimental program to validate and refine our formulation.

Evaluation of high shear viscosity data from jet and concentric cylinder viscometers

1962 ◽  
Vol 2 (1) ◽  
pp. 82-87 ◽  
Author(s):  
Roger S. Porter ◽  
Julian F. Johnson
Keyword(s):  
Shear Viscosity ◽  
Viscosity Data ◽  
High Shear ◽  
Concentric Cylinder
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