On the boundary layer structure near a highly permeable porous interface

Dalwadi, Mohit P., Chapman, S. Jonathan, Waters, Sarah L. and Oliver, James M. (2016) On the boundary layer structure near a highly permeable porous interface. Journal of Fluid Mechanics, 798 . pp. 88-139. ISSN 1469-7645

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The method of matched asymptotic expansions is used to study the canonical problem of steady laminar flow through a narrow two-dimensional channel blocked by a tight-fitting finite-length highly permeable porous obstacle. We investigate the behaviour of the local flow close to the interface between the single-phase and porous regions (governed by the incompressible Navier--Stokes and Darcy flow equations, respectively). We solve for the flow in these inner regions in the limits of low and high Reynolds number, facilitating an understanding of the nature of the transition from Poiseuille to plug to Poiseuille flow in each of these limits. Significant analytical progress is made in the high-Reynolds-number limit, and we explore in detail the rich boundary layer structure that occurs. We derive general results for the interfacial stress and for the conditions that couple the flow in the outer regions away from the interface. We consider the three-dimensional generalization to unsteady laminar flow through and around a tight-fitting highly permeable cylindrical porous obstacle within a Hele-Shaw cell. For the high-Reynolds-number limit, we give the coupling conditions and interfacial stress in terms of the outer flow variables, allowing information from a nonlinear three-dimensional problem to be obtained by solving a linear two-dimensional problem. Finally, we illustrate the utility of our analysis by considering the specific example of time-dependent forced far-field flow in a Hele-Shaw cell containing a porous cylinder with a circular cross-section. We determine the internal stress within the porous obstacle, which is key for tissue engineering applications, and the interfacial stress on the boundary of the porous obstacle, which has applications to biofilm erosion. In the high-Reynolds-number limit, we demonstrate that the fluid inertia can result in the cylinder experiencing a time-independent net force, even when the far-field forcing is periodic with zero mean.

Item Type: Article
RIS ID: https://nottingham-repository.worktribe.com/output/787645
Additional Information: Copyright Cambridge University Press 2016
Keywords: Boundary layers, Boundary layer structure, Porous media
Schools/Departments: University of Nottingham, UK > Faculty of Medicine and Health Sciences > School of Life Sciences
Identification Number: https://doi.org/10.1017/jfm.2016.308
Depositing User: Dalwadi, Dr Mohit
Date Deposited: 27 Apr 2016 08:14
Last Modified: 04 May 2020 17:49
URI: https://eprints.nottingham.ac.uk/id/eprint/32960

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