Understanding the instability of particle-laden liquids over soft porous media
Abstract
The goal of this project is to provide the basis for understanding the stability of particle laden liquids over porous materials. This concept inspired by the almost frictionless movement of blood cells through capillaries, involves covering the planar surfaces with an array of porous material with permeability and porosity similar to goose down. The specific objective of this project is to present a theoretical framework that models and predicts the instability of micro particle suspensions in a channel in which one or two walls coated with porous media and hence, shed light on the roles played by particle particle and particle wall interactions near a wall, flow chamber geometry, suspensions and porous material properties on such instabilities. The steady concentration of particles in the pressure driven flow of suspensions through a channel can be disturbed when there are complicating mechanisms such as sedimentation, particle-wall and particle-particle interactions near a wall. These disturbances can induce small fluctuations in the boundary values of the particle volume fraction and generate global modes. Largely unexplored suspensions dynamics emerge when particle laden liquids flow over permeable media. In addition, Newtonian fluid flow past soft porous materials has exhibited instabilities, therefore, suspension rheology could amplify or dampen such instabilities. In this project, linear stability analysis, carried out via spectral methods will be used to model perturbations from the coupled Brinkman equation and suspension models. The proposed project has these research objectives: 1) Develop an analytical model that accurately describes the motion of particle laden liquids for high volume fractions over porous materials with specific mechanical properties by coupling the Brinkman equation with the suspension balance model. To understand the instability in the system, we linearly perturb the steady state coupled equations and use Chebshev tav spectral methods to define the eignmodes of the perturbed equations; 2) Experimentally validate that model using MRI and PIV measurements and examine the onset of instability in the system. This research will be the first to comprehensively address the instability of Poiseuille flow in a suspension porous medium system. This is a novel continuum scale framework that uses experimentally validated models and theory that describe the coupling behavior of suspension and permeable media and enables exploration of the influence of parameters from both suspension and porous media. For instance, the instability in the system can be described giving specific geometrical features of the channel characteristics of the porous media and property of suspension flow. It is hypothesized that: 1) Instability in the system depend explicitly on Reynolds number, suspension flow and porous media properties, channel geometry, and the thickness of porous media, and 2) For dilute suspension flows (i.e., Àbulk<0.05) over a porous media, instability depends specifically on the porous media properties, channel geometry, and the thickness of porous layers. As Àbulk increases (i.e. 0.05<Àbulk<0.5), these instabilities will be either enhanced or reduced. The analytical model will be validated with experiments to find the velocity and concentration profiles in the system. The outcomes of the study will provide an understanding of the instability analysis of the particle laden flows over walls coated with porous media and its comparison with smooth surfaces will lead to novel methods to manufacture the surfaces and control particles in the flow as well as near the wall in a wide range of industrial applications and technologies related to the processing and transports of suspension flows.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810356
Entities
People
- Parisa Mirbod
Organizations
- Army Contracting Command
- United States Army
- University of Illinois at Chicago