🚀 go-pugleaf

In article <1993Jan21.131854@roper.mc.ti.com> W. Donald Rolph:
> I agree completely with Han.

Well, at least we come close.

> the problem is indeed tractable, ...

Theoretical yes, practical no. Even if it is possible, theoretically, to
couple the solid with the fluid equations, then it is still not possible,
in practice, to solve a true "demanding" Fluid-Structure application, due
to the amount of work involved. While carrying out the unification process,
attention must be given to: how to interface FV and FE practices, as they
are actually implemented today. (Mind that it is already difficult to build
a proper interface for different FEA packages!)

> Han you have brought up upwind differencing for the convective term before.
> I reference Zienkiewicz 1977 starting on page 633 where he discusses
> applying upwind differencing for the convective term using fea procedures.
> If these equations are consistent with your fv upwind differencing, ...

And, as we both agree upon, such interfacing problems do not seem to exist
for the diffusive part of the equations.

As far as I can see, FE shape function upwinding is _not_ consistent with
FV upwinding. So here remains work to be done. However, I think a far better
place to start is the "streamline upwind differencing" technique, currently
employed by FLOTRAN. The latter product is especially interesting, because
accompanying documents explicitly refer to FV techniques of Patankar et al.
But most of all, it is unified _commercially_ with a well known FEA vendor:
ANSYS. So there should be hope for practical Fluid-Structure calculations
in the near future. Unless they don't get the message ...

> If the above paragraph sustains critical review, then my position is an even
> more optimistic one than yours, that is to say yes we need a merging of the
> two techniques - I agree completely, but further that the math to merge the
> two techniques already exists.

I am a bit less optimistic concerning the "math that already exists":
IMHO a few pieces of the puzzle are still missing.

> ONE universal numerical method can be achieved today!

Sustained, anyway.
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