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[Nolan Dyck <question230574@xxxxxxxxxxxxxxxxxxxxx>]

New question #230574 on Yade:
https://answers.launchpad.net/yade/+question/230574

Hi,

This is a follow up to a question I asked a few weeks ago. I am using yade to model randomly generated periodic domains of spherical void phase porous media (I simply interpret the solid spheres in the yade simulation as revolved cuts in CAD). So far I have been quite successful in modifying some of the python scripts to produce very nice looking periodic geometries that I have been able to conduct pore level CFD simulations on using commercial software. Now in order to move forward and start generating more physically realistic representations of graphite foam I need to be able to correctly model the force displacement relationships between bubbles.

Unfortunately the force displacement relationship between 2 interacting bubbles is very non-linear. It is also unfortunate that none of the other interaction models that yade currently supports (such as the Hertz-Midlin contact theory) is applicable to bubbles. As explained in a paper called Film drainage and coalescence between deformable drops and bubbles by Chan et. al (2010) two interacting bubbles have an approximate force-displacement relationship of:

D = (F/[2*PI*S])*log(F/[4*PI*S*{R1+R2}])

Where D is the separation between the surfaces of the two bubbles, F is the normal reaction force between the bubbles, S is the surface tension of the fluid (a material constant), and R1 and R2 are the radii of the interacting bubbles. This equation is a highly simplified version of the one in the paper for my application. A big problem is that I need to solve for the force when given the displacement. This means the solution must be iterative.

This post has become very long but I now arrive at my problem. I am still very new to Yade and python (and new to Unix for that matter) and I find the prospect of modifying Yade itself to implement the contact law very daunting. Can someone point me in the right direction on how to do this? What classes do I need to create? Which existing contact law should I use as a template? Is there a simple trick I can use in python to make this happen without diving into the c++ code? I'm just a master's student and this work is not really the core of my thesis so I can't really commit to working on this for very long. I would feel more inclined to do this if the community felt that this is a worthwhile addition to yade, and if someone would be willing to maintain the code after I am finished.

Thanks,
Nolan

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