Viscoelastic Fluid Flows using OpenFOAM The solver viscoelasticFluidFoam
 

Hello Foamers,

My name is Jovani and I want announce that will soon be available a solver for treatment of viscoelastic fluid in OpenFOAM. I was working in the development of a viscoelasticFluidFoam solver (with the great orientation of the Dr. Hrvoje Jasak, thank you very much Hrvoje!!) to simulate viscoelastic flows.

The follow models are implemented: Maxwell, Oldroyd-B, Giesekus, PTT linear and exponential,
FENE-P, FENE-CR and DCPP. There are others models already implemented but not tested (Pom-Pom, SXPP, DXPP, WM ...).

The metodology used to obtain solutions in high We numbers was the DEVSS. The test geometry was mainly the 4:1 planar contraction. The solver are able to simulate multimode cases with n modes.

For the interested: A presentation that will soon be available on line to give more informations.

Jovani

Brilliant work, Jovani! Do
 

Brilliant work, Jovani!

Do you think I could take a look at the sources? This is something we were looking to implement, but it looks like you've saved us the trouble!

Hello Menon, Yes, the solve
 

Hello Menon,

Yes, the solver will be available in the -dev version of OpenFOAM, but you need wait untill the solver is put into the source. Don't be worried, this will be done soon.

Jovani

Hi Jovani, Great work! This
 

Hi Jovani,

Great work! This will speed up research in viscoelastic simulations a lot. 8-)
Really great!
Greetings
Kerstin

A piece of propaganda: Jovani
 

A piece of propaganda: Jovani did this work under a Masters project at Universidade Federal Rio Grande do Sul, Brazil and we are trying to convince him to stay on and do a PhD along similar lines.

Can I ask the audience to kindly help me in this.

Hrv

Hi Jovani, great job! And t
 

Hi Jovani,

great job! And the fact that it was made under a master's project is simply terrific! Great.

And... You should just listen to Hrvoje! Go on with CFD and do a PhD. So we can wait for more good to come in the field of viscoelastic flow simulations! http://www.cfd-online.com/OpenFOAM_D...part/happy.gif

best
Holger

Thanks everyone!! Thanks Hr
 

Thanks everyone!!

Thanks Hrvoje for the propaganda!

Marschall, I'm thinking to a PhD. There are a lot of studies to be done in this area.
As there isn't much in this area into commercial softwares, I think that if we do any efforts, with the help of Hrvoje of course, we can create something top of line.

Jovani

Hello Jovani, Thank you for
 

Hello Jovani,

Thank you for your good work. When will the next solver be released?

Ning

Hi Jovani, that all looks v
 

Hi Jovani,

that all looks very promising.

However, could you give some details about the stability of your solver:

- up to which We (or De)-Number stable solutions can be obtained in your 4to1 planar geometry?

- any tests on realistic 3-D geometries and if, what is the performance in terms of CPU-time?

cheers Max

Hello All, Ning, the solver
 

Hello All,

Ning, the solver will released in this month or the maximum in April. I believe I will not have time to test some models (white-Metzner and derivations, PP, XPP and Feta-PTT) but their will be into the solver too. Is necessary validate these models.


Max,

About the De numbers: I make any test to explore this question, but only for some models (PTT and Giesekus). But to give to you a number I simulate a case that I simulate was a LDPE flow with De=250 using Giesekus 8-mode model, this was't the limit for this case, I simply don't tried higher values. A complete study to this maximum Deborah values need to be done. Other, the DEVSS methodology sugest an arbitrary value for the the term added to moment equation, generally is used the value of etaP (value that is used in the solver), but we know that the better value for this term is related with each model and your parameters, this need more study too and I think with it's possible obtain any improvements. The interpolation shemes used also afect it.

About 3-D simulations: I do a test with a realistic case that was the flow into a capillary with a contraction. The mesh was about 150000 volumes, considering 2 simetry planes. As is make the transient simulation the Courant number control the time step, but the simulation time is acceptable for me. I used multigrid and parallelization tecniques for it.

file:///home/jovani/Desktop/PresentationSolver/pictures/magtautri2.png

file:///home/jovani/Desktop/PresentationSolver/pictures/meshtri.png


Jovani

Hello All, Ning, the solver
 

Hello All,

Ning, the solver will released in this month or the maximum in April. I believe I will not have time to test some models (white-Metzner and derivations, PP, XPP and Feta-PTT) but their will be into the solver too. Is necessary validate these models.


Max,

About the De numbers: I make any test to explore this question, but only for some models (PTT and Giesekus). But to give to you a number I simulate a case that I simulate was a LDPE flow with De=250 using Giesekus 8-mode model, this was't the limit for this case, I simply don't tried higher values. A complete study to this maximum Deborah values need to be done. Other, the DEVSS methodology sugest an arbitrary value for the the term added to moment equation, generally is used the value of etaP (value that is used in the solver), but we know that the better value for this term is related with each model and your parameters, this need more study too and I think with it's possible obtain any improvements. The interpolation shemes used also afect it.

About 3-D simulations: I do a test with a realistic case that was the flow into a capillary with a contraction. The mesh was about 150000 volumes, considering 2 simetry planes. As is make the transient simulation the Courant number control the time step, but the simulation time is acceptable for me. I used multigrid and parallelization tecniques for it.

file:///home/jovani/Desktop/PresentationSolver/pictures/magtautri2.png

file:///home/jovani/Desktop/PresentationSolver/pictures/meshtri.png


Jovani

Ops, Sorry!!! An error occu
 

Ops, Sorry!!!

An error occurred, I sent twice the same message and the pictures do not is showed. I believe the pictures appears now.

U magnitude:


http://img24.imageshack.us/img24/174/magutri2.png][IMG]http://img24.imageshack.us/img24/174/magutri2.th.png[/IMG][/URL]


Stress magnitude:

http://img6.imageshack.us/img6/6859/magtautri2.png][IMG]http://img6.imageshack.us/img6/6859/magtautri2.th.png[/IMG][/URL]

Mesh:

http://img22.imageshack.us/img22/9122/meshtri.png][IMG]http://img22.imageshack.us/img22/9122/meshtri.th.png[/IMG][/URL]

Jovani

Hello Jovani

I am interested in knowing if the solver is released yet.

I also would like to know, before switching to OpenFOAM, if it possible to model two phase flows, one of the phase having specific viscoelastic properties.

Thank you

Mike

Hi Michael,
In principle nothing is impossible in OpenFOAM. ;-)
I guess handling the viscoelastic stresses correctly in the region, where you don't have a sharp interface is the most tricky part...I mean to make it really physical.
But how do you intend to do it, if you don't switch to OpenFOAM? Everything I can imagine to do as alternative (commercial code or own code) will be much more difficult than in OpenFOAM...
Greetings
Kerstin

Hello Mike,

Kerstin is rigth about OpenFOAM :)

The solver was not release yet! I am finishing the tests Hrvoje ask me to do and I need talk with him about it in this days.
About free surface viscoelastic flow: Yes is possible in OpenFOAM, I am simulate rod-climming and die swell, but this work are just beginning, few tests for the methodology was done untill now!!

I advert you when the solver is released.

Best,
Jovani

viscoplastic constitutive model
 

Hi,
Jovani,

I am planing to use OpenFOAM to simulate aluminum extrusion which is viscoplastic constitutive model. Will you give the viscoplastic constitutive model in the future? I think maybe for you it is a very easy work to do. But I just don't know how to do it and where I can get started to do it by myself. Could you please give me some advice?
Attatchment is the constitutive model. Thank you.

Wendy.

Hi Wendy,

What do you mean mathematically with D^d in the .doc?
D is a tensor and what is meant with the power of d???

At the moment I don't see any viscoelastic part in your equation. Viscoelastic properties are related to the left hand side (time derivative) of a constitutive equation. You should have a look on the theory of linear viscoelasticity, where material behaviour and equations are explained with spring's and dash-pots...(keyword: Maxwell fluids... ) you only have an explicit equation for stress tensor as a function of deformation gradient tensor with non constant viscosity...

but please explain the D^d further, bacause your material law looks interesting...
Kerstin

Hi, thank you.

It is a viscoplastic model , not viscoelastic.
D is rate of deformation tensor, the superscript d represents deviator.
the equation for D is as attathment.

Thank you very much.

Wendy

Hi, I have another constitutive model , maybe it is easier to realize. please see the attathment.
Thank you .
Have a nice day.

Wendy

No pressure... but Jovani has got his examination on Monday - just registering support in public :)

Hrv