governing equations for fluid flow and phase transfers

Submitted by jestep on Fri, 06/11/2010 - 04:48

As a beginner to DEM and granular dynamics I am interested in knowing the equations LIGGGHTS is solving for fluid flow and phase transfers. I'm familiar with Navier-Stokes, however the CFD-DEM portion on this site refers to a 'volume fraction' introduced to account for the granular particles; and to phase transfers of energy, mass, and momentum. I assume the particle-particle interactions are treated with MD Hertz force law solving for F = ma. I'm not sure how this volume fraction is implemented to the N-S eq's, or how to describe fluid-particle interactions - especially exchange of energy, momentum, and mass between the phases. Is there a way to view or access these equations?

Cheers,
Joe

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ckloss's picture

ckloss | Fri, 06/11/2010 - 09:08

Hi Joe,

just to clarify things: LIGGGHTS is a DEM solver, and does not solve for the Navier-Stokes equations. It would not make sense to re-invent a CFD solver, as there are good ones available to start from. And yes, particle-particle interactions are treated with an MD approach in a Lagrangian frame of reference, e.g. using a Hertz law. See the doc of LIGGGHTS for more infos, if you download the tarball, see doc/manual.html.

As far as the coupled CFD-DEM technique is concerned, this has not been released yet on our website, but we will release a first basic version during the next weeks. To answer your questions regarding the CFD-DEM technique, you may want to have a look at the following publication:
http://omd2.wikispaces.com/file/view/OSCIC2009_CFD-DEM-Goniva_PA.pdf

Best,
Christoph

jestep | Fri, 06/11/2010 - 19:04

Christoph,

So the LIGGGHTS package is strictly for granular applications without interstitial fluid interactions; I thought it implemented the CFD-DEM coupling. Thanks for the clarification - the publication you provided helps also. I expect that your solver will prove very useful for my work.

Cheers,
Joe