[Nek5000-users] surface tension (Marangoni effect) driven flows

Fri Apr 2 10:52:51 CDT 2010

On Fri, 2010-04-02 at 14:30 +0200, nek5000-users at lists.mcs.anl.gov
wrote:
> Yes, I think we can handle that using our new NEK-NEK capabilities!

Hi Stefan,

That is very nice to hear!  Question; what does NEK-NEK stand for?

Cheers,
Frank

> The motivation for developing the NEK-NEK feature was slightly different though. The plan was to enable simulations with complex geometries and/or to have local high resolution zones without suffering from topological constraints.
> 
> No, I don't think we have a customer dealing with surface tension driven flows. But I could be wrong.
> @Paul: you may want to comment on that?
>  
> -Stefan
> 
> On Apr 2, 2010, at 2:17 PM, nek5000-users at lists.mcs.anl.gov wrote:
> 
> > On Fri, 2010-04-02 at 14:02 +0200, nek5000-users at lists.mcs.anl.gov
> > wrote:
> >> Ok I see. It's hard to say if NEK can handle a problem like this.
> >> Do you know what's needed on a solver level to tackle such a problem?
> > 
> > Hi Stefan,
> > 
> > My idea of the coupling would be to (at each time step):
> > 
> > 1)  solve the liquid using some guess for the velocity and temperature
> > at the interface
> > 
> > 2)  define the tangential stress at and heat flux across the interface
> > from using the values of the velocity and temperature in the liquid
> > 
> > 3)  using the tangential stress and heat flux from 2 as boundary
> > conditions, solve for the gas (including at the interface).
> > 
> > 4) using the velocity and temperature at the interface found in 3, goto
> > 1 and repeat till convergence.
> > 
> > 
> >> 
> >> I think you want to run two NEK instances which are coupled through an interface boundary condition, right?
> > 
> > Yes, that would be the goal. Each instance would have different fluid
> > properties, and be connected to the other through the mentioned BCs at
> > the interface.
> > 
> > Are you aware of any uses of Nek5000 to solve surface tension (Marangoni
> > effect) driven flows?
> > 
> > Cheers,
> > Frank
> > 
> >> 
> >> Stefan
> >> 
> >> 
> >> On Apr 2, 2010, at 1:49 PM, nek5000-users at lists.mcs.anl.gov wrote:
> >> 
> >>> On Fri, 2010-04-02 at 13:30 +0200, nek5000-users at lists.mcs.anl.gov
> >>> wrote:
> >>>> Hi Frank,
> >>>> 
> >>>> I guess you have to deal with a sharp interface in your two-phase flow problem.
> >>>> The question is how do you resolve this interface having in mind (a) accuracy and (b) boundness (stability).
> >>>> 
> >>>> High-order methods are typically less robust to under-resolution and you need to play some tricks to get a bounded solution (e.g. using flux-limiters).
> >>>> 
> >>>> How do you plan to tackle this problem?
> >>> 
> >>> Hello Stefan,
> >>> 
> >>> The interface does not need to be resolved, it is known.  The situation
> >>> is the following.  There is a liquid drop surrounded by gas.  The
> >>> surface tension of the liquid is high enough that the shape of the
> >>> liquid (i.e., the interface) is not affected by the flow in the liquid
> >>> or in the gas.  Therefore the shape of the interface is determined
> >>> entirely by the contact angle and gravity.  However, the gas "sees" the
> >>> liquid and vice versa, thanks to the continuity of velocity,
> >>> temperature, tangential stress and heat flux across the interface.  It
> >>> is worth noting that, taking an incompressible gas and liquid, the
> >>> pressure level of the gas is not coupled to that of the liquid.  So the
> >>> problem can be thought of as two separate simulations which have a
> >>> boundary across which they share the above boundary conditions.  So not
> >>> a true two-phase flow.
> >>> 
> >>> Cheers,
> >>> Frank
> >>> 
> >>>> 
> >>>> 
> >>>> -Stefan
> >>>> 
> >>>> 
> >>>> On Apr 2, 2010, at 1:14 PM, nek5000-users at lists.mcs.anl.gov wrote:
> >>>> 
> >>>>> Hello all,
> >>>>> 
> >>>>> I am interested in the opinion of users and developers as to whether it
> >>>>> is practical to use Nek5000 for a "two-phase" flow problem.  I write
> >>>>> "two-phase" since the interface between the two fluids is fixed, with
> >>>>> only the shear stress and tangential velocity matched there (normal
> >>>>> velocity being zero) and temperature and normal heat flux.  In addition,
> >>>>> on the liquid side of the interface there is a shear stress proportional
> >>>>> to the temperature gradient along the interface (Marangoni effect).  
> >>>>> 
> >>>>> Also, am I correct in understanding that all components of velocity are
> >>>>> stored at the same location (the Gauss–Lobatto–Legendre points), while
> >>>>> the pressure is located at the Gauss–Legendre points?  This being in
> >>>>> contrast to a MAC type staggered grid, where each velocity component
> >>>>> resides at different spatial locations.
> >>>>> 
> >>>>> Cheers,
> >>>>> Frank
> >>>>> 
> >>>>> -- 
> >>>>> 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
> 
> _______________________________________________
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-- 
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