Understanding the instability of particle-laden liquids over soft porous media
Abstract
The major goal of the proposed project is to quantitatively examine the suspension flows over porous media and the related instabilities by developing and experimentally validating a new framework to model and understand the stability of the flow of particle-laden liquids in a rectangular channel in which one or two walls are coated with various porous media. The proposed concept, inspired by the nearly frictionless movement of red blood cells through tiny capillaries, involves covering the planar surfaces with a specific porous material with permeability K and porosity ?. The specific objectives of the proposed project, described below, are aimed at achieving our major goal of developing and experimentally validating a new theoretical framework to model and understand this coupled flow and the causes of instability in the system. In Objective# 1, we will consider pressure-driven channel flow of non-Brownian, non-colloidal particle-laden liquids at moderate to high concentrations (i.e., 0.05<?bulk<0.5) in which one or two walls is/are coated with various porous media. We will couple the Brinkman equation and the suspension balance model to understand the velocity profile and concentration field above the porous media and to define the steady-state (base state) solutions in the presence of the permeable media. Then, we will linearly perturb the coupled equations in the steady-state regime. The Chebyshev tau method will be utilized to determine the eigenmodes of perturbed equations. The PI plans to validate and calibrate the code by performing and reproducing the results of [2,11]. Finally, the stability of the system will be analyzed, the normalized amplitude of the stream function and concentration profiles, and the new families of stable/unstable modes will be determined. A phase diagram that summarizes the effect of Reynolds number and flows? property, channel geometry, and physical property of the porous media on instability will be also introduced. In Objective# 2, we will experimentally validate the theoretical predictions. We will design and construct an experimental test set-up and its supporting structures which will allow us to flow suspensions in a channel over surfaces coated with and without a porous layer and to investigate the onset of instability. The set-up will be fully instrumented to measure the steady-state velocity and concentration profiles in the channel over the porous layer at low to moderate Reynolds number. We plan to perform Osborne Reynolds experiment to define the onset of the instability in the system for dilute to concentrated suspensions. The slurry will be composed of poly(methyl methacrylate) (PMMA) particles with a mean radius of 100Ð150 ?m. Particle concentrations of 1% to 50% will be tested. We will employ particle image velocimetry (PIV) measurements to characterize the flow, to define the velocity profiles, at dilute suspensions (i.e., ?bulk =1% and 5%). Magnetic resonance imaging (MRI) will be used to define the concentration distribution and velocity profiles for dilute to concentrated suspensions (i.e., ?bulk =1% and 50%). The data will be compared with the analytical calculations performed in Objective 1. Discrepancies will be noted, their potential sources will be investigated, and approaches to decreasing the errors will be explored.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Oct 06, 2018
- Source ID
- W911NF1710406
Entities
People
- Parisa Mirbod
Organizations
- Army Contracting Command
- Clarkson University
- United States Army