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Reply To: High density/viscosity ratio Free Energy method

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Michael Rennick

Dear Amirmansour,

Unfortunately, the current implementation of the free energy method is not capable of handling high density or viscosity ratios.

For high viscosity ratios, a possible solution would be to introduce a variable relaxation time that depends on the concentrations. OpenLB offers an implementation of dynamics with variable relaxation times, so this could be used to solve the density and velocity fields. However, implementing this for the Free Energy method would require defining a specific coupling between the different distributions and specifying a dependence of the relaxation time on the concentration.

Regarding the density ratio, the current model assumes constant densities for all phases. Modifications to the model would be necessary to accommodate phases with different densities. Numerical stability is also a concern, and there are several approaches to address this issue, each with their own nuances. As a result, incorporating high density ratios would be considerably more complex.

Best wishes,