OpenLB – Open Source Lattice Boltzmann Code Forums on OpenLB General Topics Multicomponent flow- water droplet splashing Reply To: Multicomponent flow- water droplet splashing

#5153
Julius
Participant

Hi Prinz,

I’m currently doing my Msc thesis on a similar topic. So while I am not an OpenLB dev, I am quite familiar with the workings. So here are my answers to your questions:

1) The ShanChen method is possible to use in OpenLB. The forces are added via a coupling given in `shanCehnForcedSingleComponentPostProcessor`. An example of that on OpenLB is given in: `examples\multicomponent\phaseSeparation`. You can give walls a fictitous density and set the surface wettability in that way.
2) I am also using Li’s method, and yes indeed it is possible to use it. You would need to create / modify a couple files however (I highly recommend create). You need an additional descriptor field in your fluid lattice to save the calculated pseudopotential. Then you need to copy the post processor, adapt it for your new NSdescriptor and save the calculated pseuodopotentials into the descriptor field. Then you need to copy the Gou forcing and modify the velocity before the force calculation, but after the collision calculations.
3) I cannot say anything about that.
4) That depends on your equation of state. Li’s method deals with the thermodynamic inconsistency when using an EoS, like the peng robinson one. I believe the instability occurs due to high spurious currents. You can use an MRT collision operator to reduce those, or decrease the repulsive coefficient in your equation of state (that is `a` in the PR EoS). While the thermodynamic inconsistency suffers a bit, I have managed to reach a density ratio of 1000 at a temperature ratio of 0.6 with the BGK collision operator in 3D.
5) External forces can be added easily. Just add to the force a `F=g*(rho_local - rho_average)`. Do note that you should exclude that force for the modified velocity when using the Li’s method.

I hope that helps you a bit further.
If any of the developers would like to chime in and correct a mistake I’ve made, please do so.

Regards,
Julius

• This reply was modified 3 years, 10 months ago by Julius.