Dispersion in porous media in oscillatory flow between flat plates: applications to intrathecal, periarterial and paraarterial solute transport in the central nervous system
Dispersion in porous media in oscillatory flow between flat plates: applications to intrathecal, periarterial and paraarterial solute transport in the central nervous system
Background: As an alternative to advection, solute transport by shear-augmented dispersion within oscillatory cerebrospinal fluid flow was investigated in small channels representing the basement membranes located between cerebral arterial smooth muscle cells, the paraarterial space surrounding the vessel wall and in large channels modeling the spinal subarachnoid space (SSS).
Methods: Geometries were modeled as two-dimensional. Fully developed flows in the channels were modeled by the Darcy-Brinkman momentum equation and dispersion by the passive transport equation. Scaling of the enhancement of axial dispersion relative to molecular diffusion was developed for regimes of flow including quasi-steady, porous and unsteady, and for regimes of dispersion including diffusive and unsteady.
Results: Maximum enhancement occurs when the characteristic time for lateral dispersion is matched to the cycle period. The Darcy-Brinkman model represents the porous media as a continuous flow resistance, and also imposes no-slip boundary conditions at the walls of the channel. Consequently, predicted dispersion is always reduced relative to that of a channel without porous media, except when the flow and dispersion are both unsteady.
Discussion/conclusions: In the basement membranes, flow and dispersion are both quasi-steady and enhancement of dispersion is small even if lateral dispersion is reduced by the porous media to achieve maximum enhancement. In the paraarterial space, maximum enhancement R max = 73,200 has the potential to be significant. In the SSS, the dispersion is unsteady and the flow is in the transition zone between porous and unsteady. Enhancement is 5.8 times that of molecular diffusion, and grows to a maximum of 1.6E+6 when lateral dispersion is increased. The maximum enhancement produces rostral transport time in agreement with experiments.
Cerebrospinal fluid, Glymphatic system, Paravascular flow, Paravenous flow, Perivascular flow, Spinal subarachnoid space
1-17
Keith Sharp, M.
70ff9aa8-e16c-4683-9618-e382125f285f
Carare, Roxana O.
0478c197-b0c1-4206-acae-54e88c8f21fa
Martin, Bryn A.
38931384-5a1d-4c99-ba18-5972edf8a5b6
6 May 2019
Keith Sharp, M.
70ff9aa8-e16c-4683-9618-e382125f285f
Carare, Roxana O.
0478c197-b0c1-4206-acae-54e88c8f21fa
Martin, Bryn A.
38931384-5a1d-4c99-ba18-5972edf8a5b6
Keith Sharp, M., Carare, Roxana O. and Martin, Bryn A.
(2019)
Dispersion in porous media in oscillatory flow between flat plates: applications to intrathecal, periarterial and paraarterial solute transport in the central nervous system.
Fluids and Barriers of the CNS, 16 (1), , [13].
(doi:10.1186/s12987-019-0132-y).
Abstract
Background: As an alternative to advection, solute transport by shear-augmented dispersion within oscillatory cerebrospinal fluid flow was investigated in small channels representing the basement membranes located between cerebral arterial smooth muscle cells, the paraarterial space surrounding the vessel wall and in large channels modeling the spinal subarachnoid space (SSS).
Methods: Geometries were modeled as two-dimensional. Fully developed flows in the channels were modeled by the Darcy-Brinkman momentum equation and dispersion by the passive transport equation. Scaling of the enhancement of axial dispersion relative to molecular diffusion was developed for regimes of flow including quasi-steady, porous and unsteady, and for regimes of dispersion including diffusive and unsteady.
Results: Maximum enhancement occurs when the characteristic time for lateral dispersion is matched to the cycle period. The Darcy-Brinkman model represents the porous media as a continuous flow resistance, and also imposes no-slip boundary conditions at the walls of the channel. Consequently, predicted dispersion is always reduced relative to that of a channel without porous media, except when the flow and dispersion are both unsteady.
Discussion/conclusions: In the basement membranes, flow and dispersion are both quasi-steady and enhancement of dispersion is small even if lateral dispersion is reduced by the porous media to achieve maximum enhancement. In the paraarterial space, maximum enhancement R max = 73,200 has the potential to be significant. In the SSS, the dispersion is unsteady and the flow is in the transition zone between porous and unsteady. Enhancement is 5.8 times that of molecular diffusion, and grows to a maximum of 1.6E+6 when lateral dispersion is increased. The maximum enhancement produces rostral transport time in agreement with experiments.
Text
s12987-019-0132-y
- Version of Record
More information
Accepted/In Press date: 16 April 2019
Published date: 6 May 2019
Keywords:
Cerebrospinal fluid, Glymphatic system, Paravascular flow, Paravenous flow, Perivascular flow, Spinal subarachnoid space
Identifiers
Local EPrints ID: 431121
URI: http://eprints.soton.ac.uk/id/eprint/431121
PURE UUID: 3db2e4c8-fb87-4caf-95da-07e59abfff9c
Catalogue record
Date deposited: 24 May 2019 16:30
Last modified: 16 Mar 2024 03:04
Export record
Altmetrics
Contributors
Author:
M. Keith Sharp
Author:
Bryn A. Martin
Download statistics
Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.
View more statistics
