Utilizing the Discrete Element Method for the Modeling of Viscosity in Concentrated Suspensions
Martin Kroupa1, Michal Vonka1, Miroslav Soos1
1Department of Chemical Engineering, University of Chemistry and Technology Prague , Technicka 5, 16628 Prague 6, Czech Republic.
Langmuir : the ACS Journal of Surfaces and Colloids
|August 2, 2016
Summary
This study models concentrated suspension viscosity using dynamic discrete element method (DEM). Results show viscosity is independent of shear rate but increases with particle volume fraction, driven by lubrication forces.
Area of Science:
- * Rheology and fluid dynamics
- * Computational physics and materials science
Background:
- * Modeling concentrated suspensions is challenging due to complex particle-fluid interactions.
- * Accurately predicting viscosity's dependence on system parameters remains difficult.
Purpose of the Study:
- * To model the viscosity of hard-sphere suspensions at high shear rates.
- * To investigate the influence of particle interactions and volume fraction on rheological behavior.
- * To develop a novel approach for handling lubrication forces in suspension modeling.
Main Methods:
- * Dynamic discrete element method (DEM) in 3D.
- * Hertz contact model for inter-particle forces (soft-sphere).
- * Two-way coupling for particle-flow interaction.
- * Lubrication theory with slip for hydrodynamic interactions.
Main Results:
- * Viscosity is independent of shear rate and primary particle size for monodisperse suspensions.
- * Viscosity increases rapidly with particle volume fraction.
- * Lubrication forces are the primary cause of observed rheological behavior.
- * A novel slip-based approach effectively addresses divergent lubrication forces.
Conclusions:
- * The DEM model accurately predicts hard-sphere suspension rheology.
- * Lubrication forces play a critical role in suspension viscosity.
- * The developed slip model offers a robust method for suspension viscosity prediction.
- * The model is versatile for incorporating various interaction physics.
Related Concept Videos
01:18Newtonian Fluid: Problem Solving
1.1K
Newtonian fluids exhibit a constant viscosity, meaning their shear stress and shear strain rate are directly proportional. This property ensures a predictable and stable response to applied forces, maintaining a linear relationship between force and flow. Examples include water, air, and light oils, consistently demonstrating this proportional behavior regardless of external conditions.
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
A velocity gradient forms within the fluid when a Newtonian fluid is placed between two parallel plates, with...
1.1K
01:09Theories of Dissolution: The Danckwerts' Model and Interfacial Barrier Model
895
Various dissolution theories provide insight into the factors that influence the dissolution rate. Danckwerts' Model suggests that turbulence, rather than a stagnant layer, characterizes the dissolution medium at the solid-liquid interface. In this model, the agitated solvent contains macroscopic packets that move to the interface via eddy currents, facilitating the absorption and delivery of the drug to the bulk solution. The regular replenishment of solvent packets maintains the...
895
01:27Viscosity
73
Viscosity is a property of fluids that measures their resistance to flow. It is influenced by factors such as the surface area of contact, the gradient of flow speed, and the fluid's viscosity constant, called the coefficient of viscosity. The coefficient of viscosity, also known as dynamic viscosity, is denoted by the symbol η. It determines the proportionality between the viscous force and the gradient of flow speed.Newton's law of viscosity states that the viscous force on a...
73
01:17Viscosity
7.7K
When water is poured into a glass, it falls freely and quickly, whereas if honey or maple syrup is poured over a pancake, it flows slowly and sticks to the surface of the container. This difference in the flow of different kinds of liquids arises due to the fluid friction between the liquid layers and the liquid and the surrounding material. This property of fluids is called fluid viscosity. In this example, water has a lower viscosity than honey and maple syrup.
The SI unit of viscosity is...
The SI unit of viscosity is...
7.7K
01:30Typical Model Studies
674
Fluid mechanics model studies often utilize scaled-down systems to predict fluid behavior in full-scale environments, such as river flows, dam spillways, and structures interacting with open surfaces. Maintaining Froude number similarity in river models is crucial, as it replicates surface flow features like wave patterns and velocities.
674
01:15Theories of Dissolution: Diffusion Layer Model
2.1K
Dissolution, the process by which drug particles dissolve in a solvent, is explained by the diffusion layer model, a theoretical framework that simulates the absorption of oral drugs and allows us to analyze experimental data.
This process starts with a thin layer, saturated with the drug, forming at the interface between the solid and liquid. The solute then diffuses from this layer into the main solution. The Noyes-Whitney equation suggests that the rate of dissolution relies on the diffusion...
This process starts with a thin layer, saturated with the drug, forming at the interface between the solid and liquid. The solute then diffuses from this layer into the main solution. The Noyes-Whitney equation suggests that the rate of dissolution relies on the diffusion...
2.1K