Effect On Particle Due to Fluid Density Change

[Jijo]

Hello OpenLB community,

I am currently working on thermally heated resolved particles.I have been investigating whether these particles are influenced by changes in fluid density, particularly in relation to the Boussinesq approximation. I experimented with such test case but I can not notice any effect on the particle’s velocity when including this effect. Any idea on such scenario?

Regards,

[jan]

Dear Jijo,

gravity is applied as a (constant) external acceleration, see accExt and apply_gravity in examples/particles/dkt2d. So the changes of the fluid density don’t affect the particle.

Also, currently the external acceleration is defined for the whole particle system. Updating it within the ParticleManager would therefore update it for all particles. In your particular case, I think it would be best to manually apply the gravity at each timestep. For example, you could evaluate the density at the current particle position if an averaged density is sufficient. If you need different forces on the surfaces, then a more sophisticated approach would be necessary.

Best regards,
Jan

[Jijo]

Dear Jan,

Thank you for your reply. I appreciate your constant support and help. The problem I am having is that the fluid itself is not flowing upward due to natural convection and I think such issue is due to the force field.

It seems that the porousparticleBGK dynamics does not contain a force field and I believe that buoyancy forces are coupled using Boussinesq forces by the Guo forcing scheme. What do you think I should do in this case?

Regards,

[jan]

Dear Jijo,

if you solely need a force field for the coupling, then perhaps try PorousParticleKupershtokhForcedBGKdynamics and see if that works.

Best regards,
Jan

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