scholarly journals Analysis of the Dispersion of Viscoelastic Clusters in the Industrial Rotor-Stator Equipment

Processes ◽  
2021 ◽  
Vol 9 (12) ◽  
pp. 2232
Author(s):  
Alexander Kolomiets ◽  
Tomas Jirout
Keyword(s):  
Shear Stress ◽  
Cfd Simulation ◽  
Good Choice ◽  
Complex Shear Modulus ◽  
Special Equipment ◽  
Complex Shear ◽  
Complex Rheology ◽  
Process Line ◽  
Specific Material ◽  
The Stability

Materials with complex rheology and viscoelasticity may require special equipment for processing, such as for dispergation. Rheological and mechanical data of the material can help with finding the required equipment or designing equipment. For highly viscous and complex material, a rotor-stator mixer can be a good choice for dispergation. Due to the laminar or creeping mechanism of flow inside the equipment, the dispergation mechanism is assumed to be a combination of the shear stress and slicing of the material by the rotor and stator blades. For the validation of the theory, the mechanical properties of the viscose identified in a previous work were used for comparison with the data from the CFD simulation of the rotor-stator mixer. The comparison showed that the rotor-stator device can overcome the complex shear modulus and ultimate strength of the material and homogenize the solution through a combination of the shear stress and slicing. The theory was also confirmed on the process line proposed for homogenization of the specific material. The stability of viscosity during the process of homogenization was measured and used as the main parameter for quality assessment.

scholarly journals The Microcantilever: A Versatile Tool for Measuring the Rheological Properties of Complex Fluids

2012 ◽  
Vol 2012 ◽  
pp. 1-9 ◽  
Author(s):  
I. Dufour ◽  
A. Maali ◽  
Y. Amarouchene ◽  
C. Ayela ◽  
B. Caillard ◽  
...  
Keyword(s):  
Shear Stress ◽  
Rheological Properties ◽  
Hydrodynamic Force ◽  
Complex Fluids ◽  
Dynamic Spectrum ◽  
Complex Shear Modulus ◽  
Confined Fluid ◽  
Complex Shear ◽  
Versatile Tool ◽  
Surrounding Fluid

Silicon microcantilevers can be used to measure the rheological properties of complex fluids. In this paper, two different methods will be presented. In the first method, the microcantilever is used to measure the hydrodynamic force exerted by a confined fluid on a sphere that is attached to the microcantilever. In the second method, the measurement of the microcantilever's dynamic spectrum is used to extract the hydrodynamic force exerted by the surrounding fluid on the microcantilever. The originality of the proposed methods lies in the fact that not only may the viscosity of the fluid be measured, but also the fluid's viscoelasticity, that is, both viscous and elastic properties, which are key parameters in the case of complex fluids. In both methods, the use of analytical equations permits the fluid's complex shear modulus to be extracted and expressed as a function of shear stress and/or frequency.

PIV Validation of Blood-heart Valve Leaflet Interaction Modelling

2007 ◽  
Vol 30 (7) ◽  
pp. 640-648 ◽  
Author(s):  
R. Kaminsky ◽  
K. Dumont ◽  
H. Weber ◽  
M. Schroll ◽  
P. Verdonck
Keyword(s):  
Shear Stress ◽  
Heart Valve ◽  
Cfd Simulation ◽  
Flow Simulation ◽  
Data Sets ◽  
Arbitrary Lagrangian Eulerian ◽  
Velocity Magnitude ◽  
Image Velocimetry ◽  
Interaction Modelling ◽  
In Series

The aim of this study was to validate the 2D computational fluid dynamics (CFD) results of a moving heart valve based on a fluid-structure interaction (FSI) algorithm with experimental measurements. Firstly, a pulsatile laminar flow through a monoleaflet valve model with a stiff leaflet was visualized by means of Particle Image Velocimetry (PIV). The inflow data sets were applied to a CFD simulation including blood-leaflet interaction. The measurement section with a fixed leaflet was enclosed into a standard mock loop in series with a Harvard Apparatus Pulsatile Blood Pump, a compliance chamber and a reservoir. Standard 2D PIV measurements were made at a frequency of 60 bpm. Average velocity magnitude results of 36 phase-locked measurements were evaluated at every 10° of the pump cycle. For the CFD flow simulation, a commercially available package from Fluent Inc. was used in combination with in-house developed FSI code based on the Arbitrary Lagrangian-Eulerian (ALE) method. Then the CFD code was applied to the leaflet to quantify the shear stress on it. Generally, the CFD results are in agreement with the PIV evaluated data in major flow regions, thereby validating the FSI simulation of a monoleaflet valve with a flexible leaflet. The applicability of the new CFD code for quantifying the shear stress on a flexible leaflet is thus demonstrated. (Int J Artif Organs 2007; 30: 640–8)

scholarly journals Simulation of the Load Evolution of an Anchoring System under a Blasting Impulse Load Using FLAC3D

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Xigui Zheng ◽  
Jinbo Hua ◽  
Nong Zhang ◽  
Xiaowei Feng ◽  
Lei Zhang
Keyword(s):  
Shear Stress ◽  
Dynamic Response ◽  
Axial Force ◽  
Mechanical Characteristics ◽  
Oscillation Amplitude ◽  
Anchoring System ◽  
Impulse Load ◽  
The Stability ◽  
Calculation Software ◽  
Dynamic Perturbation

A limitation in research on bolt anchoring is the unknown relationship between dynamic perturbation and mechanical characteristics. This paper divides dynamic impulse loads into engineering loads and blasting loads and then employs numerical calculation software FLAC3Dto analyze the stability of an anchoring system perturbed by an impulse load. The evolution of the dynamic response of the axial force/shear stress in the anchoring system is thus obtained. It is revealed that the corners and middle of the anchoring system are strongly affected by the dynamic load, and the dynamic response of shear stress is distinctly stronger than that of the axial force in the anchoring system. Additionally, the perturbation of the impulse load reduces stress in the anchored rock mass and induces repeated tension and loosening of the rods in the anchoring system, thus reducing the stability of the anchoring system. The oscillation amplitude of the axial force in the anchored segment is mitigated far more than that in the free segment, demonstrating that extended/full-length anchoring is extremely stable and surpasses simple anchors with free ends.

Flexural Vibrations of an Elastic Plate With Two Symmetric Viscoelastic Coatings

1967 ◽  
Vol 34 (1) ◽  
pp. 187-194
Author(s):  
Paul Hertelendy ◽  
Werner Goldsmith
Keyword(s):  
Composite Plate ◽  
Flexural Vibration ◽  
Complex Shear Modulus ◽  
Viscous Effects ◽  
Approximate Methods ◽  
Linear Viscoelastic Material ◽  
Complex Shear ◽  
Linear Viscoelastic ◽  
Modal Behavior ◽  
Viscoelastic Coatings

The flexural-vibration characteristics of a symmetric, doubly infinite composite plate consisting of two outer layers of a linear viscoelastic material bonded to an elastic core have been examined, the viscous effects in the coating being represented by a complex shear modulus. Calculations of the dispersive and damping effects have been obtained for the lowest three modes by an extension of the exact Rayleigh-Lamb equations. Loss factors of the lowest modes have also been evaluated by two readily computed approximate methods; the results have been compared with those from the exact solution. The material constants were chosen to be representative of a high-polymer coating and an aluminum core. The modal behavior of the systems and coupling effects are discussed.

scholarly journals A sensitive dynamic viscometer for measuring the complex shear modulus in a steady shear flow using the method of orthogonal superposition

1995 ◽  
Vol 34 (6) ◽  
pp. 606-621 ◽  
Author(s):  
Jos Zeegers ◽  
Dirk van den Ende ◽  
Cor Blom ◽  
Egbert G. Altena ◽  
Gerrit J. Beukema ◽  
...  
Keyword(s):  
Shear Flow ◽  
Shear Modulus ◽  
Steady Shear ◽  
Complex Shear Modulus ◽  
Complex Shear ◽  
Steady Shear Flow ◽  
Dynamic Viscometer

CFD SIMULATION OF SHEAR STRESS AND SECONDARY FLOWS IN URETHRA

2007 ◽  
Vol 19 (02) ◽  
pp. 117-127 ◽  
Author(s):  
Yang-Yao Niu ◽  
Ding-Yu Chang
Keyword(s):  
Shear Stress ◽  
Cfd Simulation ◽  
Three Dimensional ◽  
Secondary Flows ◽  
Normal Female ◽  
Urinary System ◽  
Stress Distributions ◽  
Computational Fluid Dynamics Cfd ◽  
Peak Value ◽  
Lower Urinary

In this work, a preliminary numerical simulation of the lower urinary system using Computational Fluid Dynamics (CFD) is performed. Very few studies have been done on the simulation of three-dimensional urine through the lower urinary system. In this study, a simplified lower urinary model with rigid body assumption is proposed. The distributions of urine flow velocity, wall pressure and shear stress along the urethra are simulated based on MRI scanned uroflowmetry of a normal female. Numerical results show that violent secondary flows appear on the cross surface near the end of the urethra when the inflow rate is increased. The oscillative variation of pressure and shear stress distributions are found around the beginning section of the urethra when flow rate is at the peak value.

scholarly journals Shear models and parametric analysis of the PVC geomembrane-cushion interface in a high rock-fill dam

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245245
Author(s):  
Yun-Feng Liu ◽  
Ke Gu ◽  
Yi-Ming Shu ◽  
Xian-Lei Zhang ◽  
Xin-Xin Liu ◽  
...  
Keyword(s):  
Shear Stress ◽  
Friction Coefficient ◽  
Three Dimensional ◽  
Viscous Friction ◽  
Hydraulic Pressure ◽  
Viscous Shear Stress ◽  
Box Counting ◽  
Viscous Shear ◽  
The Stability ◽  
Hysteresis Friction

As a type of flexible impermeable material, a PVC geomembrane must be cooperatively used with cushion materials. The contact interface between a PVC geomembrane and cushion easily loses stability. In this present paper, we analyzed the shear models and parameters of the interface to study the stability. Two different cushion materials were used: the common extrusion sidewall and non-fines concrete. To simulate real working conditions, flexible silicone cushions were added under the loading plates to simulate hydraulic pressure loading, and the loading effect of flexible silicone cushions was demonstrated by measuring the actual contact areas under different normal pressures between the geomembrane and cushion using the thin-film pressure sensor. According to elastomer shear stress, there are two main types of shear stress between the PVC geomembrane and the cushion: viscous shear stress and hysteresis shear stress. The viscous shear stress between the geomembrane and the cement grout was measured using a dry, smooth concrete sample, then the precise formula parameters of the viscous shear stress and viscous friction coefficient were obtained. The hysteresis shear stress between the geomembrane and the cushion was calculated by subtracting the viscous shear stress from the total shear stress. The formula parameters of the hysteresis shear stress and hysteresis friction coefficient were calculated. The three-dimensional box-counting dimensions of the cushion surface were calculated, and the formula parameters of the hysteresis friction were positively correlated with the three-dimensional box dimensions.

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