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convecting an inert scalar with a robust solver
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Brian  
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 More options Feb 1, 12:26 am
From: Brian <maxwellbr...@yahoo.ca>
Date: Sat, 31 Jan 2009 21:26:19 -0800 (PST)
Local: Sun, Feb 1 2009 12:26 am
Subject: convecting an inert scalar with a robust solver
Hi guys,

I am trying to model a non-reactive case of high pressure hydrogen
being released into air (a pressure ratio of 100 to 1000).  If I solve
the EulerEquations I have to use a robust solver like the Godunov
solver or the simulation will fail.  The Roe solver generates a NAN
because it cannot handle the high strength shock that is generated in
the simulation.  What I would like to do is convect an inert scalar
(I'll call it alpha) in order to track where the two gases are
throughout the release process.  The equation I would like to add to
the solver is:

d(rho*alpha)/dt + d(rho*u*alpha)/dx + d(rho*v*alpha)/dy = 0

One approach I have tried is to use the ReactiveEulerEquations set and
use Z as my tracking variable.  I made it non-reactive (or inert) by
setting the solver variables Q and K to zero.  However I can only find
the Roe solver option in the ReactiveEulerEquations.  Is there a
robust solver I can use with the ReactiveEulerEquations in order to
run a simulation that can handle strong shocks, or am I better off to
add the equation above to the EulerEquations via the add2W option?  If
so is there a way I can easily integrate alpha using the godunov
solver routine that calculates the other variables (RHO, P, U, V, E)?
Has anyone tried this, or have examples?

Thanks,

Brian


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James Quirk  
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 More options Feb 2, 12:13 am
From: James Quirk <j...@galcit.caltech.edu>
Date: Sun, 1 Feb 2009 21:13:42 -0800 (PST)
Local: Mon, Feb 2 2009 12:13 am
Subject: Re: convecting an inert scalar with a robust solver
Brian,

Try running the example:

     amrcp bcg/axs.3

it generates 108 different solvers for the ReactiveEulerEquations.

Also, take a look at:

     amrcp contrib/sk.mailit

it shows how you might construct a two material solver,
although note that the script could do with polishing
as t was written way back in 1999 and is a bit klunky.

James


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