| 2017-12-07 15:46:49 |
Bruno Chareyre |
description |
In the basic PFV scheme the incremental change of density of a pore fluid after a change of pore volume is dependent on dV/Vo where Vo is the reference pore space within a tetrahedral cell [1], i.e. V(tetrahedron)-V(spheres).
In DFNFlow "V" should reflect the fact that porosity may be mainly due to a crack an its opening.
Typically V=V(tetrahedron)-opening*area-matrixPorosity.
Currently it is using the same formula, hence overestimating the compressibility effect (because the DEM porosity is larger than a typical rock porosity). What should be the reference "opening" in above formula is to be clarified though, it has physical as well as numerical implications. Maybe slotInitialAperture is a candidate? Let you DFN people tell what it should be.
Note that the "dV" is less a problem because it is a difference (independent on the choice of the reference volume), so the incompressible scheme is not affected.
Bruno
[1] https://github.com/yade/trunk/blob/master/pkg/pfv/FlowEngine.ipp.in#L439 |
In the basic PFV scheme the incremental change of density of a pore fluid after a change of pore volume is dependent on dV/Vo where Vo is the reference pore space within a tetrahedral cell [1], i.e. V(tetrahedron)-V(spheres).
In DFNFlow "V" should reflect the fact that porosity is mainly due to cracks, i.e. it is much smaller than the numerical porosity calculated between spheres.
Typically V=opening*area+matrixPorosity*cellVolume
Currently it is using the same formula, hence overestimating the compressibility effect (because the DEM porosity is larger than a typical rock porosity). What should be the reference "opening" in above formula is to be clarified though, it has physical as well as numerical implications. Maybe slotInitialAperture is a candidate? Let you DFN people tell what it should be.
Note that the "dV" is less a problem because it is a difference (independent on the choice of the reference volume), so the incompressible scheme is not affected.
Bruno
[1] https://github.com/yade/trunk/blob/master/pkg/pfv/FlowEngine.ipp.in#L439 |
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