ESyS-Particle

Multiple bond interactions

Asked by riche

Hi All,

I have been using Esys particle to simulate various de-agglomeration mechanisms of pharmaceutical powder clusters. I have been able to use GenGeo to generate a spherical poly-disperse particle packing. To Further my model, I wish to create the following but am not sure how to approach it:

-I need to create a sphere (diameter 2) packed with particles diameter explicitly either 0.1 or 0.02 .
-I then need to create bonds of type A between the 0.1 & 0.02 diameter particles (adhesive) and another type of bond B between the smaller 0.02 diameter particles (cohesive). Together, these bonds should hold the agglomerate together.
(I am guessing the trick is to implement some kind of tagging to these particles, but i have no idea how to achieve this.)

-on a separate note, does anyone know/has come across any literature which specifies the cohesive or adhesive forces between pharma powders such as mannitol or lactose? or the best way to represent those bonding forced in Esys? I have played around with a few but im not %100 sure which is the best due to the inputs required (elastic mod etc)

Any help will be greatly appreciated, apologies if the answer to this question is simple and i have not looked hard enough!

Thanks again,

Yours Sincerely,

Rich

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SteffenAbe (s-abe) said : 		#1

Hi Rich,

> -I need to create a sphere (diameter 2) packed with particles diameter explicitly either 0.1 or 0.02 .
This is going to be tricky because the current packing algorithm in gengeo doesn't allow the generation of a stricktly bimodal (only diameters 0.1 or 0.02 allowed) particle distribution. You can only provide a particle size range but you can't influence the size distribution within this range.

I don't have an idea at the moment how to get around this restriction but it would probably involve implementing a completely different packing algorithm.
If you could relax your size condition so that you' pack 2 distinct ranges of particle sizes, say 0.07-0.14 and 0.015-0.03, then it _might_ be possible to modify the current packing algorithm to work with this constraint.

Steffen

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riche (rmoh0041) said : 		#2

Hi Steffen,

Thanks for your time, this relaxation can be made. Making the ranges 0.07-0.14 and 0.015-0.03 should be fine. If anything, this will make the model more realistic considering the naturally occurring particles will not be exactly one of 2 size. How involved would the modification of the algorithm be to achieve this? My coding is very limited and im starting to thing this may be out of reach.

cheers

Rich

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SteffenAbe (s-abe) said : 		#3

Hi Rich,

> How involved would the modification of the algorithm be to achieve this?
Its not a fundamental problem, but it would involve some semi-tricky C++ coding and it might take some time. Basically you'd need to sub-class InsertGenerator3D in the C++ core of GenGeo, modify the seedParticles and the fillIn functions so they don't produce particles in a single radius range but from 2 distinct ranges. You'd also need to add a Python interface to the new class but that's largely copy-and-paste.
If you'd like to have a shot at it I can try to give you some guidance.

Steffen

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