[okkervb]

Hey,

I am trying to simulate the extraction of a specie from one liquid-phase to an other liquid phase in a parallel flow setup. I've come quite far in setting-up the model, but now have to tune it to fit my specific problem. As far as I understand I have to define a UDF for the transfer from one phase to the other, but I'm not sure what Macro should be used for this. Is there anyone who could give me some insight into this.

Further more I do not know how I can incorporate the partition coefficient of the dissolved specie into the model, should this be part of the UDF defining the specie transfer between the two phases

My model has multiphase turned on in a VOF model, with laminar viscous model and species transport on. The energy model is turned off.

Kind regards,
Okker

[vinerm]

It depends on the physical mechanism responsible for mass transfer. Are both liquids immiscible? If not, you do not need multiphase. If both are immiscible, then you need to look at the physical phenomenon that causes the mass transfer. If it is due to partial pressures, then you can use inbuilt models, such as, Raoult's law or equilibrium. However, if there is some other mechanism, then you can use DEFINE_MASS_TRANSFER or DEFINE_LINEARIZED_MASS_TRANSFER. If the mass transfer is because of reactions, then you can either directly use reactions or same functions as mentioned earlier.

[okkervb]

Thank you for your reaction,

In my case both fluids are immiscible, and the mass transfer happens because of a concentration difference of the dissolved specie between the two phases, taking the partitioning coefficient into account. So only because of diffusion.

The idea is to model the extraction of metal-ions from an aqueous phase to a organic phase. For the mass-transfer mechanism options within fluent I could only see the option to give a constant rate or evaporation/condensation and cavitation.

Regards,
Okker

[vinerm]

The options you are seeing are for the phase change. If both of the phases represent mixtures of components, then you can use Multiphase Species Mass Transfer. That would be suitable for your application.