# 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: 8 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: 8
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, 68 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: 8 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: 8 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: 8
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, 86 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?

 Tags free surface, interfoam, marangoni, thermocapillary

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