Re: [sparta-users] [EXTERNAL] RE: EXT :Re: collision models

[Madan B K <mad...@wm...>]

Hi Rama,
If you are ultimately interested in gas–solid interactions, one possible approach (instead of trying to treat solids as another DSMC “species”) is to use a DEM–DSMC coupling framework. In that setup, the gas phase is modeled with DSMC (e.g., SPARTA), while the solid particles are resolved with a discrete element method (DEM) solver, and the momentum/energy exchange is handled through one-way or two-way coupling between the two solvers.
That may be a more natural and flexible way to treat solid particles than trying to define a mixed HS/VHS collision model within a single DSMC framework.

Madan B K

________________________________
From: Gallis, Michael A. via sparta-users <spa...@li...>
Sent: Tuesday, November 4, 2025 6:31 PM
To: Ramakrishnan, Sekaripuram [US] (DS) (Contr) <Sek...@ng...>; Steve Plimpton <sj...@gm...>
Cc: spa...@li... <spa...@li...>
Subject: Re: [sparta-users] [EXTERNAL] RE: EXT :Re: collision models


Attention: This email is from outside Western Michigan University. Use caution when opening links and attachments.

I thought I answered this question during the Santa Fe meeting.
The answer is absolutely not. Particles follow a different mathematical model than molecules.

Michael


From: Ramakrishnan, Sekaripuram [US] (DS) (Contr) <Sek...@ng...>
Date: Tuesday, November 4, 2025 at 4:20 PM
To: Steve Plimpton <sj...@gm...>
Cc: spa...@li... <spa...@li...>, Gallis, Michael A. <ma...@sa...>
Subject: [EXTERNAL] RE: EXT :Re: [sparta-users] collision models


Thank you, Steve.



Rama



From: Steve Plimpton <sj...@gm...>
Sent: Tuesday, November 4, 2025 3:18 PM
To: Ramakrishnan, Sekaripuram [US] (DS) (Contr) <Sek...@ng...>
Cc: spa...@li...; Gallis, Michail A <ma...@sa...>
Subject: EXT :Re: [sparta-users] collision models



I'm CCing Michael who may be able to comment on whether a mixed HS/VHS collision model makes sense

for a solid/gas particle mixture.  It sounds like you are really asking for a mixture of 3 models in one simulation:

solid/solid, gas/gas/ and solid/gas.



If it does make sense, then we could think about how to implement it.



Steve



On Sun, Oct 5, 2025 at 12:19 PM Ramakrishnan, Sekaripuram [US] (DS) (Contr) <Sek...@ng...<mailto:Sek...@ng...>> wrote:



I am wondering whether such a collision model may be used to simulate a mixture of solid and gas particles with HS model for solid particles and VHS model foe gas particles.



Rama





From: Ramakrishnan, Sekaripuram [US] (DS) (Contr) <Sek...@ng...<mailto:Sek...@ng...>>
Sent: Sunday, October 5, 2025 11:40 AM
To: spa...@li...<mailto:spa...@li...>
Subject: EXT :[sparta-users] collision models



Is there a model for collision between a hard sphere and a variable hard sphere?



Rama

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