# Thermocapillary free surface flow

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 May 7, 2009, 04:30 #2 Member   Hamed Aghajani Join Date: Mar 2009 Location: London, UK Posts: 77 Rep Power: 17 Dear Zaki, Have you had any success in solving your problem? please let me know, Best, Hamed

May 19, 2009, 07:29
#3
New Member

Zaki Saldi
Join Date: Mar 2009
Posts: 18
Rep Power: 17
Hi Hamed,

I think I have moved one very small step forward in solving the problem with the tangential force. Now I have a modified interFoam to account for this thermocapillary effect. However, after testing the code, I was not satisfied with the result in comparison with the one in literature.

Please find the source code and the test case in the attachment. The test case is thermocapillary motion of deformable drops in a vertical temperature gradient (no gravity), which follows the one reported in:

www.stanford.edu/group/ctr/Summer/SP08/3_2_Lopez.pdf

I tested the first problem in that paper (case of limit of zero marangoni number, page 161-162), and comparing my result with figure 1 (page 162).

Please kindly have a look at it and I would appreciate it if you could give comments, suggestions, help.

regards,

zaki

Attached Files
 marangoniInterFoam.tar.gz (9.5 KB, 248 views)

 May 19, 2009, 11:17 adding Temprature to les/interfoam #4 Member   Hamed Aghajani Join Date: Mar 2009 Location: London, UK Posts: 77 Rep Power: 17 Dear Zaki, Thanks for updating the thread, I want to add temperature to les/interFoam? The equation I am trying to add is; (1) rho*Cp*[ddt(gamma*T)+grad(gamma*U*T)]=laplacian(gamma*Landa_eff*T) I know that, a surfaceScalarField should be exist to update thermal conductivity in each time step (2) {Landa_eff = Landa + Cp*nuSgs()}, I have Les Turbulence Model as well. To comply the Eq.2, should I modify a new library for Landa(Thermal conductivity), to call it in TEqn as twoPhaseProperties.landa(), or something else. I also tried with Creatfield and it didn't worked. Please elaborate, Kindly, Hamed hamed.aghajani@gmail.com h.aghajani@kingston.ac.uk

 May 19, 2009, 12:01 #5 New Member   Zaki Saldi Join Date: Mar 2009 Posts: 18 Rep Power: 17 Hi Hamed, My questions & remarks: 1. Why do you need gamma in the energy equation (eq. 1) ? 2. Seems to me the terms in eq 2 are dimensionally inconsistent. I think they should be like this: suppose landa = thermal conductivity, and alpha thermal diffusivity. so alpha = landa/(rho*Cp) landa_eff = landa + landa_sgs = landa + rho*Cp*alpha_sgs = landa + rho*Cp*nu_sgs / Pr_t where Pr_t is the turbulent Prandtl number. It is of course elegant to define landa (or its cell-face value landaf) in a new library. But I think you can also do it like this: - define landa as volScalarField, also constants landa1 & landa2 for each fluid - after calculating gamma, define landa = landa1*gamma + landa2*(1-gamma), also similarly with Cp - before solving energy equation: surfaceScalarField gammaf = fvc::interpolate(gamma); surfaceScalarField landaf = fvc::interpolate(landa); surfaceScalarField landaEff ( "landaEff", landaf + fvc::interpolate(rho*Cp*turbulence->nuSgs()/Pr_t) ); kind regards, zaki

May 20, 2009, 13:23
#6
Member

Hamed Aghajani
Join Date: Mar 2009
Location: London, UK
Posts: 77
Rep Power: 17
Dear Zaki,

I saw the eq.(1) in a paper, Cryogenics 48 (2008) 238–247, and have not understood why the autors chose the energy equation in that form. But I attached part of that paper to this thread. you can find it in eq.8;

I couldn't call turbulent Prandt number and the TEqn, as you suggested,I wrote is;
surfaceScalarField landaf = fvc::interpolate (landa);
surfaceScalarField landaEff
(
"landaEff"
landaf
+ fvc::interpolate(rho*Cp*turbulence->nuSgs())
);

fvScalarMatrix TEqn
(
rho*Cp*
(fvm::ddt(T)
+ fvm::div(phi, T)
)
- fvm::laplacian(landaEff, T)
);

TEqn.solve();

It is running on a case and I haven't checked the result yet,

Kindly,
Hamed
Attached Files
 interfoam development.pdf (63.5 KB, 219 views)

 August 24, 2014, 03:24 thermocapillary #7 New Member   Join Date: Aug 2014 Posts: 1 Rep Power: 0 how can i coding thermocapillary flows in a confined microchannel with LBM method?

 December 9, 2016, 20:22 #8 Member   Kalpana Hanthanan Arachchilage Join Date: May 2015 Location: Orlando, Florida, USA Posts: 30 Rep Power: 10 Dear Dr. Zaki, I've referred to your PhD dissertation as I'm planning to implement and validate the tangential component of the surface tension force. I've tried to simulate the cavity simulation you used to validate surface tension force. However, i'm not getting the correct result. One thing i noticed is they provided data to obtain the physical properties of liquid. but, it didn't mention anything about the vapor side physical properties. Can you please let me know, what kind of physical properties you used for vapor side. Thank you, Kalpana Hanthanan Arachchilage

December 12, 2016, 04:59
#9
Member

Ricky
Join Date: Jul 2014
Location: Germany
Posts: 78
Rep Power: 11
Quote:
 Originally Posted by kal1943335 Dear Dr. Zaki, I've referred to your PhD dissertation as I'm planning to implement and validate the tangential component of the surface tension force. I've tried to simulate the cavity simulation you used to validate surface tension force. However, i'm not getting the correct result. One thing i noticed is they provided data to obtain the physical properties of liquid. but, it didn't mention anything about the vapor side physical properties. Can you please let me know, what kind of physical properties you used for vapor side. Thank you, Kalpana Hanthanan Arachchilage
Hello Kalpana,

If I am not wrong, are you trying to validate your case in two-phase environment compared to Dr. Saldi's single-phase? If yes, then there are 2 more test cases you could actually use to validate your tangential component of the surface tension force.
1) Is already mentioned here (see post -> #3)
2) you could also validate your case with his "Two-Phase Marangoni driven flows" (sec 3.5 of his thesis) --> which I am trying to do currently but the results are way off. In my case the surface height at left wall is 0.194 and at the right wall is 0.204.

Perhaps you may come up with some better solution.

Regards,
Ricky

Last edited by kera; December 12, 2016 at 08:53.

December 12, 2016, 10:20
#10
Member

Kalpana Hanthanan Arachchilage
Join Date: May 2015
Location: Orlando, Florida, USA
Posts: 30
Rep Power: 10
Quote:
 Originally Posted by kera Hello Kalpana, If I am not wrong, are you trying to validate your case in two-phase environment compared to Dr. Saldi's single-phase? If yes, then there are 2 more test cases you could actually use to validate your tangential component of the surface tension force. 1) Is already mentioned here (see post -> #3) 2) you could also validate your case with his "Two-Phase Marangoni driven flows" (sec 3.5 of his thesis) --> which I am trying to do currently but the results are way off. In my case the surface height at left wall is 0.194 and at the right wall is 0.204. Perhaps you may come up with some better solution. Regards, Ricky
Dear Ricky,
Thank you for your reply. Actually i was referring to section 3.5. As these non-dimensional numbers are only based on liquid properties, you have no idea what kind of properties you should use to the vapor side. I'm using interfoam based solver and i'm also getting similar results that you obtained. However, I assumed liquid and vapor properties to be equal. but, when i used different properties for vapor solution changes and I'm wondering what kind of property i have to use. The other thing is spurious currents.

I have tried the droplet simulation as well, but those curved surfaces increase spurious currents and over predicting the results.

there is another test case you can simulate. these are the references for that.

N.Balcazar et al/ International journal of heat and fluid flow (2016)
H.Liu et al/ Journal of computational physics 231 (2012) 4433-4453

Will let you know if there is any improvement. And please let me know what are the vapor properties you used for the above simulation.
Regards,
Kalpana

 December 12, 2016, 11:44 #11 Member   Ricky Join Date: Jul 2014 Location: Germany Posts: 78 Rep Power: 11 Hello Kalpana, Well I am using interfoam for the time being. Initially I assumed both the fluids have same properties, I had a solution which was no way to be considered and then I assumed second fluid as air, I had another solution but it's kinda miss leading as the surface height on the left and right walls goes upto 0.182 and 0.216 or something like that. Regards, Ricky Last edited by kera; December 12, 2016 at 12:54.

 Tags free surface, interfoam, marangoni, thermocapillary