And just to keep the discussion going: I think Medale's algorithm was
specific to incompressible flows. The low Mach number (slightly compressible)
equations the OP asked about are a bit different, if I recall correctly.
J
John Peterson writes:
> Forwarded from Ben Kirk to libmeshusers.
>
>
> Benjamin Kirk writes:
> > John, Derek  NASA is blocking me from a direct post to the libmesh mailing
> > list. I'll trust you to forward this along...
> >
> > In short, yes. Take a look in ~benkirk/phd/code/s3.implicit/src/* in the
> > cfdlab.
> >
> > The formulation of interest is denoted rbm_medale and used Mark Medale's
> > pressure projection method for the RayleighBenardMarangoni problem.
> >
> > I seriously doubt that the code compiles right now, but the gist is as
> > follows:
> >
> >  three systems are used for flow, pressure, and temperature, respectively.
> >  the momentum system is updated using an old pressure
> >  a possion problem is solved for pressure
> >  the momentum is updated using this pressure such that div(u)=0
> >  the thermal system is then solved.
> >
> >
> > The rough idea is this:
> >
> > (U_new  U_old)/dt = (grad(P) + N(U_new))
> >
> > is replaced by
> >
> > (U_*  U_old)/dt = N(U_*)
> > (U_new  U_*)/dt = grad(P)
> >
> > Note that if you add them you kinda get the original PDE back.
> >
> > Now,
> >  solve for U_*
> >  solve div(grad(P) = div(U_new  U_*)/dt =  div(U_*)/dt
> > since we require div(U_new)=0
> >  solve (mass matrix projection) U_new = U_*  dt*grad(P)
> > Barring any algebra mistakes.
> >
> > The code probably will not compile (it is from January 2004) but you can see
> > all the elements in there.
> >
> > Ben
> >
> >
> >
> > On 8/24/07 1:09 PM, "John Peterson" <peterson@...> wrote:
> >
> > > spdomin writes:
> > >> Greetings,
> > >>
> > >> Has anyone coded an equal order, low Mach number, i.e., acoustically
> > >> incompressible, pressure projection algorithm within libMesh? If so, I would
> > >> be very interested to learn more about the details of the libMesh
> > >> implementation.
> > >>
> > >
> > > I don't believe so, but I could be mistaken. Does the equalorder
> > > interpolation
> > > require stabilization of some type? Do you have a reference for the scheme
> > > you speak of? I might be able to take a quick glance and see if there's
> > > anything which would make it impossible or difficult to do in the current
> > > library.
> > >
> > > J
