[Nek5000-users] Question about method & error

Thu Apr 8 15:40:29 CDT 2010

Hi Frank,

Any idea of BCs for the gas phase?

What about the Reynolds number?

Cheers,

Paul

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

> On Thu, 2010-04-08 at 06:54 -0500, nek5000-users at lists.mcs.anl.gov
wrote:
> 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.

Hi Paul,

I had to step out for a bit, back for the rest of the night though.
That would be very kind of you.  The dimensions are: 
http://tetra.fluid.tuwien.ac.at/fmuldoo/public_html/temp/schematic-3d-liquid-bridge-3.png

Cheers,
Frank

> 
> 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
> > >
> > > _______________________________________________
> > > Nek5000-users mailing list
> > > 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
> 
> _______________________________________________
> Nek5000-users mailing list
> 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

_______________________________________________
Nek5000-users mailing list
Nek5000-users at lists.mcs.anl.gov
https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users