Fluid solid interaction

[Gloriousface]

Hello，

I am using SC multicomponent model to simulate the contact angle of droplets on solid surface. Can I ask if the interaction between fluid and solid wall is realized in SC model？

Thanks and Regards,
Gloriousface

[mathias]

If you refer to the OpenLB examples, that is a Free Energy Model and not SC. BEst Mathias

[Gloriousface]

Thank you very much for your reply, but I have another question. The user guide says that the density of each component in the free energy model is the same. How can I achieve different densities？

[savis]

Unfortunately it’s not possible in the free energy model that’s currently implemented, and it would be quite a large undertaking to do so. If the effect of different densities is required then it would probably be easiest to implement the fluid-solid interaction in the SC model. I have discussed this before here.

The issue back then was that an indicator for the solid is required but not accessible within the lattice coupling. So a work-around will be required if you want to take this route.

Best,
Sam

[Gloriousface]

Thank you very much for your reply.

[Gloriousface]

I changed the contact angle by changing the virtual density in rayleighTaylor2d, but I’m not sure whether it reflects the fluid solid force. I don’t understand why changing the virtual density and the value of force will change the contact angle? I would appreciate it if you could answer my question.

Best
Gloriousface

• This reply was modified 2 years, 11 months ago by Gloriousface.

[savis]

To my understanding, changing the virtual density would affect the contact angle because the increased / decreased density gradient with the gas increases / decreases the solid-gas surface energy. So the solid-liquid area changes to reduce the total surface energy. This therefore affects the contact angle in a similar way to changing the fluid-solid force, which may be sufficient depending upon what you are doing.

However, I don’t believe it truly models the interaction with the solid because this would require a Neumann boundary condition in the density rather than a Dirichlet condition. There is more detail about this in chapter 9 of ‘The Lattice Boltzmann Method: Principles and Practice’ if you are interested.

Apologies for the delayed response.
Sam

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