A bio-inspired strategy to dramatically reduce drag of particle-laden liquids over planar surfaces: characterization, theory and experiment

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This proposal describes a unified study that will reveal the interactions of the motion of particles in a suspension flowing over a wall where slip-type boundary conditions exist. This research is transformative because it will be the first to comprehensively address the slow motion of particle-laden liquids over soft porous material and its related drag reduction. This project will substantially advance understanding of the behavior of slurry flows over highly compressible porous media in which the fiber can act as a lubricating layer, with the potential to vastly increase lift and reduce drag. The experimental methods and analysis techniques developed could also be applied to the motion of suspensions and non-Newtonian fluids over a broad array of structured/patterned surfaces such as hydrophobic surfaces. The insights gathered could significantly advance microfluidic-based devices in a wide range of industrial applications including, biomedical fields, chemical synthesis, (cell) biology, food, and pharmaceutics to drastically reduce friction and wear, leading to improved efficiencies and operating lifetimes for these devices. Teaching materials for this unified subject will be created by introducing suspension flows as an example of non-Newtonian fluid mechanics and their interaction with porous media to the engineering students. Undergraduates will participate as researchers in this project through the McNair summer research program, Clarkson's REU program in Sustainability, Clarkson's Honors program, or through a research elective. The goal of the proposed research is to provide the basis for understanding the flow of particle-laden liquids over soft porous materials, and use that understanding to explore a new bio-inspired concept for greatly enhancing the lubricating pressure while dramatically reducing friction and drag in a particle-laden slurry flowing over planar surfaces. This concept, inspired by the almost frictionless movement of red blood cells through capillaries, involves covering the planar surfaces with an array of soft porous material with a specific permeability and porosity. The objectives of the proposed project are to 1) develop an analytical model that accurately describes the slow motion of slurries over random arrays of soft porous media with specific mechanical properties by coupling the Brinkman equation with the diffusive flux model, and establishing scaling laws for coupled flows, and 2) experimentally validate that model by a specially designed experimental set-up using pressure drop as a means to measure drag reduction and magnetic resonance imaging (MRI) and particle-image velocimetry (PIV) to measurement fluid velocities.