[titio]

Hi foamers,

I am trying to use the viscoelasticFluidFoam to model the flow of complex fluids in microfluidic systems. To test the code, and to get an idea of its behaviour and performance, I am running the case of the flow between infinite plates, where several analytical solutions for different constitutive equation models are available.

So far, I got the following results of my comparisons.

- For low values of the Deborah number (De), simulated results agree well with the theory.
- When I increase the value of the De number, it starts to deviate, increasing the deviations with De.
- When I run the solver with a null value for the solvent viscosity, I only can get convergence for very small values of De.
-Depending on the value of the density, the solver converges or diverges.

I used the linear version of the PTT model in my simulations, based on the example given in the tutorial, changing of course the mesh.

After talking with some people with knowledge in the area, they refered that there may be a problem in the wall boundary conditions. In particular, for viscoelastic fluids it is not correct to impose zero gradient boundary conditions for the extra tension. I am reading the literature now concerning this question and it looks like one needs to implement specific boundary conditions in the walls for these fluids.

Does anyone has any idea what kind of boundary conditions I should use, and how to do it.

Thanks in advance for any assistance,

Regards,

Titio