Related Experiment Video
Updated: May 31, 2026
09:08
Measuring Material Microstructure Under Flow Using 1-2 Plane Flow-Small Angle Neutron Scattering
Published on: February 6, 2014
Shear banding in thixotropic and normal emulsions
José Paredes1, Noushine Shahidzadeh-Bonn, Daniel Bonn
1Van der Waals-Zeeman Institute, University of Amsterdam, Amsterdam, The Netherlands.
Summary
Yield stress materials often flow inhomogeneously. This study shows shear banding in emulsions, particularly in thixotropic yield stress materials, due to a critical shear rate.
Area of Science:
- Rheology
- Fluid Dynamics
- Materials Science
Background:
- Yield stress materials transition from solid-like to liquid-like states when stress exceeds a critical threshold.
- Heterogeneous stress in materials leads to non-uniform flow behavior.
- Emulsion flow in cone-plate geometry typically represents a homogeneous stress scenario for Newtonian fluids.
Purpose of the Study:
- To investigate shear banding phenomena in emulsion flows within a cone-plate geometry.
- To differentiate between shear banding mechanisms, including wall slip and critical shear rate.
- To identify the specific conditions under which shear banding occurs in yield stress materials.
Main Methods:
- Utilizing a rheometer to control and measure material flow properties.
- Employing confocal laser scanning microscopy to obtain detailed velocity profiles.
- Analyzing emulsion flow behavior in a cone-plate rheometer.
Main Results:
- Shear banding was observed in emulsion flows, deviating from homogeneous flow expected for Newtonian fluids.
- Two distinct causes for shear banding were identified: wall slip and the existence of a critical shear rate.
- The study confirmed that shear banding related to a critical shear rate is exclusive to thixotropic yield stress materials.
Conclusions:
- Shear banding in emulsions is not solely dependent on heterogeneous stress but can arise from material-specific properties.
- Thixotropic yield stress materials exhibit a distinct shear banding mechanism linked to a critical shear rate.
- The combination of rheometry and advanced microscopy provides critical insights into complex fluid flow behaviors.
More Related Videos
08:42Challenges in Rheological Characterization of Highly Concentrated Suspensions — A Case Study for Screen-printing Silver Pastes
Published on: April 10, 2017
10:28Experimental Measurement of Settling Velocity of Spherical Particles in Unconfined and Confined Surfactant-based Shear Thinning Viscoelastic Fluids
Published on: January 3, 2014
Related Concept Videos
01:27Types of Fluids
Fluids can be classified into Newtonian and non-Newtonian fluids based on their response to shear stress. Newtonian fluids have a linear relationship between shear stress and the shear strain rate, following Newton's law of viscosity. Their viscosity remains constant regardless of the shear rate, making their behavior predictable and easier to analyze. Common examples include water, air, oil, and gasoline.
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and their...
In contrast, non-Newtonian fluids do not follow Newton's law of viscosity, and their...
01:22Problem Solving on Stress and Strain
Stress is a quantity that describes the magnitude of a force that causes deformation, generally defined as internal force per unit area. When forces pull on an object and cause its elongation, like the stretching of an elastic band, it is called tensile stress. When forces cause the compression of an object, it is known as compressive stress. When an object is being squeezed uniformly from all sides, like a submarine in the depths of the ocean, we call this kind of stress bulk stress (or volume...
01:17Colloids and Suspensions
Children at play often make suspensions such as mixtures of mud and water, flour and water, or a suspension of solid pigments in water known as tempera paint. These suspensions are heterogeneous mixtures composed of relatively large particles visible to the naked eye or seen with a magnifying glass. They are cloudy, and the suspended particles settle out after mixing. The suspended particles in a suspension settle out after some time of mixing. The separation of particles from a suspension is...
01:14Normal and Shear Force
When a beam is subjected to different loads, such as weight, pressure, or other external forces, internal forces are generated within the beam. These forces can have a significant impact on the overall stability and strength of the structure. Engineers use various methods to analyze and determine the magnitude and direction of these internal forces. One common technique used to determine internal forces in beams is the method of sections. This method involves considering an imaginary point or...
01:18Shearing Stress
Shearing stress, denoted by the Greek letter tau (τ), is stress caused by forces acting transversely on an object. These forces create internal ones within the entity in the plane where the external forces are applied. The resultant of these internal forces is the shear in the section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
The average shearing stress can be calculated by dividing the shear by the area of the cross-section.
01:15Thin-Walled Hollow Shafts
In analyzing a thin-walled hollow shaft subjected to torsional loading, a segment with width dx is isolated for examination. Despite its equilibrium state, this segment faces torsional shearing forces at its ends. These forces are quantitatively described by the product of the longitudinal shearing stress on the segment's minor surface and the area of this surface, leading to the concept of shear flow. This shear flow is consistent throughout the structure, indicating a uniform distribution of...