4 research outputs found
Pore-scale Modeling of Viscous Flow and Induced Forces in Dense Sphere Packings
We propose a method for effectively upscaling incompressible viscous flow in
large random polydispersed sphere packings: the emphasis of this method is on
the determination of the forces applied on the solid particles by the fluid.
Pore bodies and their connections are defined locally through a regular
Delaunay triangulation of the packings. Viscous flow equations are upscaled at
the pore level, and approximated with a finite volume numerical scheme. We
compare numerical simulations of the proposed method to detailed finite element
(FEM) simulations of the Stokes equations for assemblies of 8 to 200 spheres. A
good agreement is found both in terms of forces exerted on the solid particles
and effective permeability coefficients
Steady-State Two-Phase Flow in Porous Media: Review of Progress in the Development of the
Scope of present article is to present the research efforts (implementing experimental
study, theoretical analysis and modeling) taken towards the development of a complete
theory for steady-state concurrent two-phase flow in porous media (the DeProF theory). The
current state of progress is outlined and open problems are addressed. First attempts are
traced back in the 1980s with the analysis, description and modeling of phenomena
governing two-phase flow in pore scale. Appropriate simulators extending over hundreds
and/or thousands of pores (network scale) were developed in the following decade (1990s);
in parallel, extensive experimental research work identified three prototype/elementary
flows comprising the average macroscopic flow, namely connected-oil pathway flow, ganglion
dynamics and drop traffic flow and mapped their relative contribution to the macroscopic
flow in terms of the process parameters.
Efforts to provide a consistent physical rationale to explain the experimental
observations, i.e. the map of prototype flow regimes, laid the grounds for developing the
DeProF (Decomposition in Prototype Flows) theory. Amongst the main results/features of the
DeProF theory was the identification of the actual operational and system parameters of
the process and the introduction – according to ergodicity principles – of the domain of
physically admissible internal flow arrangements of the average macroscopic flow.
Use of the respective mechanistic model as a simulation tool (in the 2000s) revealed many
characteristic properties of the sought process. Important is the existence of optimum
operating conditions in the form of a smooth and continuous locus in the domain of the
process operational parameters. This characteristic remained in latency within the
relative permeability curves, until recently unveiled by the DeProF theory. Research
efforts continue in the present (2010s) by elaborating appropriate physical considerations
based on statistical thermodynamics and the introduction of the aSaPP (as Spontaneous as
Physically Possible) concept that corroborates the correlation of the process efficiency
to the multiplicity of the internal flow arrangements