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atzberg / mango-selm

Simulation methods for particle systems, materials, and complex fluids with fluctuating hydrodynamics approaches (stochastic immersed boundary methods, stochastic eulerian-lagrangian methods) [interfaces with LAMMPS MD package]
http://atzberger.org/
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ellipsoid implementation #23

Open rowanwalker96 opened 1 year ago

rowanwalker96 commented 1 year ago

Hi there,

Can mango selm handle finite sized spherical and non-spherical objects? I can see there are other Lagrangian types referenced such as SELM_Lagrangian_LAMMPS_ATOM_STYLE_ELLIPSOID.h which makes me think this is possible.

If so, what files in the model directory would I need to change to set up such a simulation?

Many thanks

atzberg commented 1 year ago

Hi Rowan,

Yes, one can handle finite sized spherical objects.

This can be done two ways (i) use a bead-spring like model of smaller particles that are linked together to form the spherical object. (ii) use a force-spreading and velocity-averaging operator that occurs over the surface of a sphere.

We discuss these two approaches in the papers:

(i) Incorporating Shear into Stochastic Eulerian Lagrangian Methods for Rheological Studies of Complex Fluids and Soft Materials., P.J. Atzberger, Physica D, Vol. 265, pg. 57–70, (2013) https://arxiv.org/abs/2212.10651

(ii) Stochastic Eulerian Lagrangian Methods for Fluid Structure Interactions with Thermal Fluctuations, P.J. Atzberger, J. of Comp. Phys., 230, pp. 2821--2837, (2011). http://arxiv.org/abs/1009.5648

and

Fluctuating Hydrodynamic Methods for Fluid-Structure Interactions in Confined Channel Geometries, Y. Wang, H. Lei, P. Atzberger, Applied Mathematics and Mechanics (Springer), January, Volume 39, Issue 1, pp 125–152, (2018). https://doi.org/10.1007/s10483-018-2253-8

The first approach can be done readily in the current implementation. The second one uses the approach of the second paper and is related to the code you reference.

I hope that helps.

Best, Paul

On Mon, Jan 23, 2023 at 6:16 AM Rowan Walker @.***> wrote:

Hi there,

Can mango selm handle finite size spherical and non-spherical objects? I can see there are other Lagrangian types referenced such as SELM_Lagrangian_LAMMPS_ATOM_STYLE_ELLIPSOID.h which makes me think this is possible.

If so, what files in the model directory would I need to change to set up such a simulation?

Many thanks

— Reply to this email directly, view it on GitHub https://github.com/atzberg/mango-selm/issues/23, or unsubscribe https://github.com/notifications/unsubscribe-auth/ACBHSZWXDFKDIVZVGHDPYM3WT2HFTANCNFSM6AAAAAAUD4UUNM . You are receiving this because you are subscribed to this thread.Message ID: @.***>

atzberg commented 1 year ago

Also, for the second approach, some additional implementation may be needed to integrate into the current SELM release. After implementing the associated codes, the main XML files to change on the modeling side would be the Main.SELM_params to specify the Lagrangian type, coupling operators, and integrator to use. The detailed parameters for those components are controlled by the files XXX.SELM_Lagrangian, XXX.SELM_CouplingOperator, and XXX.SELM_Integrator. See the /examples/particle1/Model1 for a typical setup for specifying these XML files, and Python/Jupyter notebooks for performing simulations.

I also would be happy to discuss more of the details involved. Just send me an email at http://atzberger.org/

Best, Paul

Paul J. Atzberger Department of Mathematics Department of Mechanical Engineering University of California Santa Barbara http://atzberger.org/