Hi everyone

I am new to both LAMMPS and this forum so please move this post if it does not belong here.

Currently I am trying to determine if there is in built functionality within the existing LAMMPS packages for pressure driven flow of colloidal suspensions, which takes into account hydrodynamic and interparticle forces (eg; particle collision). For a bit of context, the system I am studying involves carbon particles (roughly 1 micron in diameter) suspended in an electrolyte solution being pumped through a square channel of 10x10x50µm at various volume fractions.

I have previously modelled this using the granular package and adding forces on the particles to represent the mean pressure applied, with fixed particles representing the walls of the channel. However, upon reviewing studies I have found that this is likely to give the incorrect velocity profile of the flow, which should be somewhat more blunted (figure 4 b, Ref. [1]). I am now looking at trying to implement equation 11 from reference [1] below which captures both hydrodynamic and non-hydrodynamic forces to determine evolution of particle positions.

(Where Fo is non hydrodynamic forces, is the average suspension velocity, R is the tensor capturing hydrodynamic forces for superscript I - particles and w - wall)

My question is, is there a package or hybrid between packages which I can use to implement equation 11 already existing? I have not had any luck diving through the forums so far to see if anyone else has done this previously.

Looking at the existing packages it looks to me that pair_style lubricate is able to calculate the hydrodynamic portion of this equation, but not the non-hydrodynamic.

Sorry for a long winded first post, and thank you for any suggestions!

References:

[1] Nott, P. R., & Brady, J. F. (1994). Pressure-driven flow of suspensions: simulation and theory. Journal of Fluid Mechanics, 275 (https://authors.library.caltech.edu/11423/1/NOTjfm94.pdf)