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- Title
Pore geometry effects on intrapore viscous to inertial flows and on effective hydraulic parameters.
- Authors
Chaudhary, Kuldeep; Cardenas, M. Bayani; Wen Deng; Bennett, Philip C.
- Abstract
In this article, the effects of different diverging-converging pore geometries were investigated, and the microscale fluid flow and effective hydraulic properties from these pores were compared with that of a pipe from viscous to inertial laminar flow regimes. The flow fields are obtained using computational fluid dynamics, and the comparative analysis is based on a new dimensionless hydraulic shape factor ß, which is the "specific surface" scaled by the length of pores. Results from all diverging-converging pores show an inverse pattern in velocity and vorticity distributions relative to the pipe flow. The hydraulic conductivity K of all pores is dependent on and can be predicted from ß with a power function with an exponent of 3/2. The differences in K are due to the differences in distribution of local friction drag on the pore walls. At Reynolds number (Re) ∼ 0 flows, viscous eddies are found to exist almost in all pores in different sizes, but not in the pipe. Eddies grow when Re→1 and leads to the failure of Darcy's law. During non-Darcy or Forchheimer flows, the apparent hydraulic conductivity Kα decreases due to the growth of eddies, which constricts the bulk flow region. At Re>1, the rate of decrease in Kα increases, and at Re >> 1, it decreases to where the change in Kα ≈ 0, and flows once again exhibits a Darcy-type relationship. The degree of nonlinearity during non-Darcy flow decreases for pores with increasing ß. The nonlinear flow behavior becomes weaker as ß increases to its maximum value in the pipe, which shows no nonlinearity in the flow; in essence, Darcy's law stays valid in the pipe at all laminar flow conditions. The diverging-converging geometry in pores plays a critical role in modifying the intrapore fluid flow, implying that this property should be incorporated in effective larger-scale models, e.g., pore-network models.
- Subjects
HYDRAULICS; FLUID mechanics; VISCOSITY; GEOMETRY; DARCY'S law; WATER seepage; GROUNDWATER flow; REYNOLDS number
- Publication
Water Resources Research, 2013, Vol 49, Issue 2, p1149
- ISSN
0043-1397
- Publication type
Article
- DOI
10.1002/wrcr.20099