[adambarfi]

Originally Posted by arash.heidarian

Hi Mr Mahmoudi
which version of openfoam you have used for this test case?
and is your solver same as the solver which i have been attached in my last post?

Dear Arash,

1- I used OF-222 for compiling that solver.

2- Nope, I modified the solver that Bruno presented it.

Regards,
Mostafa

[arash.heidarian]

Thanks Mr mahmoudi:
but my solver was uploded by Mr burono too.
I cant compile it on of_222.
Is it posible for you to attach the solver?
thanks a lot.

[arash.heidarian]

Hi
Does any one know where can I fine viscoelastic properties?.(I mean the etap_etas_lapanda)

[Supersale]

Originally Posted by arash.heidarian

Hi
Does any one know where can I fine viscoelastic properties?.(I mean the etap_etas_lapanda)

What do you mean? in the case files or values for these parameters?
For the case files, they are located in constant/transporProperties
As for the physical values, they are ridiculously hard to obtain i found. One source was Jovani's paper: http://www.sciencedirect.com/science...70794610280069
here he uses the Giesekus model, which is not included in the solver of Mr Bruno, but it is very easily added. you have to copy it form the transport modesl of FOAMextend (there is a folder for the Giesekus model) and add it to viscoelasticTwoPhaseMixture.C . Take a look at the file and you will see how to do it. you will have to slightly change a few parameters (i think alpha and one more were in question, just check it out) and recompile it.
as for values for other parameters, you can find some sort or resources on the net (but nothing much), google some of these parameters:
eta_S - solvent viscosity (try 0.002　for the liquid, 0 for air)
eta_P - polymeric viscosity (try 1.2　for the liquid, 1e-7 for air)
lambda - relaxation time (try 0.3　for the liquid, 0 for air)
alpha - mobility factor (try 0.15　for the liquid, 0 for air)
L2 - extensibility
epsilon - extensibility parameter

[arash.heidarian]

Thanks a lot Mr Goran
It was really helpfull.

[Supersale]

OK i have a problem, stability related.

i managed to recreate Favero's results (as much as possible given i don't have some of the parameters) and it works like a charm.

Now i am trying to simulate ink-jet flow using a harmonically changing pressure function, and the problem occurs after a few steps of runtime when the stress close to the nozzle exit increases drastically and simulation crashes. the ink is just weakly viscoelastic so there shouldn't be much stress at all and this happen in the air region where the flow is set to be newtonian.

i have tried to change the schemes to be as stable as possible, but then i have another problem, the stress changes until some point and even though the flow continues, the stress field stays the same after that point, which of course is nonsense.

So any advice here? would be grateful

[jnorth]

A common problem in viscoelastic fluids is the stress singularity that arises due to irregularities on the geometry, e.g. if you have corners, then you will have increased stresses and presssure there. Thus, check your pressure field on the nozzle corners. If you are able to do it, just apply slip condition on these walls, which I believe will smooth out the singularity that arises.

[rugge]

Originally Posted by Supersale

OK i have a problem, stability related.

i managed to recreate Favero's results (as much as possible given i don't have some of the parameters) and it works like a charm.
....

Dear Sasa, is it possible to get a worked out example? It would be of great help.

Thank you

[Supersale]

Originally Posted by rugge

Dear Sasa, is it possible to get a worked out example? It would be of great help.

Thank you

rugge, I am sorry but at currently i do not have a working example i can send to you as i did this research at my old company and do no longer have access to these files. i plan to recreate the experiment though and will send the file up here once i do

[maxviet]

Hello viscoelasticFoamers,

I am currently working on OF 3.0+. I downloaded the solver viscoelasticInterFoam and modified some of the includes in order to make it compiled properly on the new OF version. I also downloaded the "case0" posted on this discussion.

My problem is :

The case runs properly, when I watch the result, the pressure, velocity and tau seem correct.

BUT : alpha.water doesn't move at all. The scalar field is innitialized via setFialeds and is at its expected location at t=0 (square located at the top of the geometry supposed to "fall" ), but this position doesn't change (despite changes in pressure and velocity)

It seems like alpha1_ is calculated correctly in the solver but is not stored in alpha.water for the result visualization.

Does anyone have a clue ?

Thanks,

Maxime

[JIM SU]

Dear maxviet,

You have to create a alphawater file in the 0 folder at t=0 separately, also you must define the required parameters in the fvsolution file of your case.
For example; CAlpha is one of them that you have to introduce in the fvsolution at the top of the body solver.

Regards,
JIM SU

[pippo2013]

Hi everybody,

I am studying a two-phase mixture in case of a dynamic mesh. Hence the equivalent of interDyMFoam but for viscoelastic flows.
Has someone already implemented it or could you give me some hints?

Any help is highly appriciated!
Thanks!!