[Nek5000-users] Question about method & error

Thu Apr 8 06:54:31 CDT 2010

Yes - this is correct.

If you can give me a rough idea of dimensions (e.g., minor-major
diameters of the bridge), I could knock something out in prenek
for you.

Paul

On Thu, 8 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote:

> Hi Paul,

Thanks very much, that is great to hear.  Is it correct that the latest
version is at:?
https://svn.mcs.anl.gov/repos/nek5/

I will try to set this up now, first thing being getting the grid (built
in Gambit) into the solver.

Cheers,
Frank

On Thu, 2010-04-08 at 04:03 -0500, nek5000-users at lists.mcs.anl.gov
wrote:
> Frank,
> 
> I think that the internal fluid interface feature is now working
> in the latest svn repo.
> 
> You will need to identify the bdry between the two fluids with "msi"
> on each given face.   Then you would specify surface tension
>
>        sigma = blah blah blah
> 
> in userbc, where blah is your desired function.
> 
> Note that you must also set lx1m, etc. to lx1 in SIZE, and 
> IFMVBD, IFSTRS to T in the .rea file.
> 
> I'll try to help you set this up - but am saturated for the next
> 7 days because of mtgs.
> 
> I've tried a couple of 2D examples and they work sufficiently
> well for your purposes (I think - but haven't investigated 
> too closely).   I'll try to post some examples in the next 48 hours.
> 
> Paul
> 
> 
> 
> On Wed, 7 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote:
> 
> >
> > Yes - I think that's it.
> >
> > I'm trying to sort out an issue with the ALE right now...
> >
> > Paul
> >
> >
> > On Wed, 7 Apr 2010, nek5000-users at lists.mcs.anl.gov wrote:
> >
> >> On Wed, 2010-04-07 at 09:54 -0500, nek5000-users at lists.mcs.anl.gov
> > wrote:
> >> Hi Frank,
> >> 
> >> Actually, the only thing that would be specified at the interface
> >> is the surface tension sigma, which would generate a jump in the stress 
> >> across the interface.  The fluid and surface would dynamically
> >> accommodate to these stresses - and would come to a steady state
> >> geometry if that's the what the dynamics dictates.   The temperature
> >> would still satisfy the heat equation, and of course you could have
> >> different rho-Cp and k in each region.
> >> 
> >> The code will generate the correct jump in pressure according to the
> >> surface tension.   (We can check this with the case of a spherical
> >> drop.)
> >> 
> >> Of course, w/o Lee around we'll have to sort all this out to make
> >> certain it does what we expect... but I'm fairly confident that it
> >> will.
> >> 
> >> Paul
> >
> > Hi Paul,
> >
> > OK, I think I understand it.  Taking the surface tension coefficient as:
> > sigma = sigma0 - sigma1*T
> > The size of the jump in the pressure between the liquid and the gas
> > would be determined by the size of sigma0 and the surface curvature.
> > This would mean then that, assuming an incompressible fluid, the only
> > effect of sigma0 would be to define the mean pressure difference between
> > the gas and the liquid.  Do this view seem correct?
> >
> > Cheers,
> > Frank
> >
> >
> >> 
> >> > Paul,
> >> > > Great to hear that.  Question; an internal interface has the meaning of
> >> > an internal boundary condition at which velocity and temperature, but
> >> > not pressure, boundary conditions can be set? > > Since the normal 
> >> velocity at the interface is set to zero and the
> >> > interface completely separates the two fluids, the absolute value of the
> >> > pressure in the two fluids is independent in the model I have in mind.
> >> > To put in other words, no pressure gradients across the interface exist
> >> > in the model.  But I guess that will always be the case in the spectral
> >> > element method, as long as the interface is not inside an element.
> >> > > Cheers,
> >> > Frank
> >> _______________________________________________
> >> Nek5000-users mailing list
> >> Nek5000-users at lists.mcs.anl.gov
> >> https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
> > -- 
> > Frank Herbert Muldoon, Ph.D. Mechanical Engineering
> > Technische Universität Wien (Technical University of Vienna)
> > Inst. f. Strömungsmechanik und Wärmeübertragung (Institute of Fluid
> > Mechanics and Heat Transfer)
> > Resselgasse 3
> > 1040 Wien
> > Tel: +4315880132232
> > Fax: +4315880132299 Cell:+436765203470
> > fmuldoo (skype)
> > http://tetra.fluid.tuwien.ac.at/fmuldoo/public_html/webpage/frank-muldoon.html
> >
> > _______________________________________________
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> > Nek5000-users at lists.mcs.anl.gov
> > https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
> _______________________________________________ Nek5000-users mailing list Nek5000-users at lists.mcs.anl.gov https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users
-- 
Frank Herbert Muldoon, Ph.D. Mechanical Engineering
Technische Universität Wien (Technical University of Vienna)
Inst. f. Strömungsmechanik und Wärmeübertragung (Institute of Fluid
Mechanics and Heat Transfer)
Resselgasse 3
1040 Wien
Tel: +4315880132232
Fax: +4315880132299 
Cell:+436765203470
fmuldoo (skype)
http://tetra.fluid.tuwien.ac.at/fmuldoo/public_html/webpage/frank-muldoon.html

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