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## libmesh-users

 [Libmesh-users] Variable-area Euler equations From: John Peterson - 2013-06-07 16:25:25 ```So this is off-topic, but I know that we have a number of CFD experts floating around on the lists... Has anyone worked with the 1D variable-area Euler equations before? I'd like to develop an SUPG formulation based on the typical quasi-linear form, in particular for general (non-ideal gas) equations of state. As far as I can tell, the variable-area aspect doesn't change the flux Jacobian matrix... it is the same as for the constant-area equations. But I must be making a very basic (and stupid!) math mistake somewhere: when I multiply (what I believe to be) the flux Jacobian matrix by the derivative of the conserved variables, I don't recover dF/dx except in the case of an ideal gas. The attached slides go into additional detail... I'd be grateful if someone could take a look and point me in the right direction -- this has been driving me crazy for a couple days now. Note that one small, but possibly significant, difference between the ideal gas EOS and a general EOS is that the flux vector F is not necessarily a "homogeneous function of degree 1" in the general case... I don't think this has any direct bearing on the quasi-linear form, but I found it initially surprising. -- John ```
 Re: [Libmesh-users] Variable-area Euler equations From: John Peterson - 2013-06-07 16:46:32 ```And... I thought I had upped the attachment limit size on the mailing list, but was just informed that it was stripped. If you are interested you can grab the slides here: https://github.com/libMesh/Documents/blob/master/presentations/applications/va_euler/va_euler.pdf -- John ```
 Re: [Libmesh-users] Variable-area Euler equations From: John Peterson - 2013-06-07 19:20:34 ```On Fri, Jun 7, 2013 at 10:46 AM, John Peterson wrote: > And... I thought I had upped the attachment limit size on the mailing > list, but was just informed that it was stripped. If you are interested > you can grab the slides here: > > > https://github.com/libMesh/Documents/blob/master/presentations/applications/va_euler/va_euler.pdf > I think I got this worked out... finally. Link above has been updated if you are interested. -- John ```