[Nek5000-users] Primer for reacting flows

[nek5000-users at lists.mcs.anl.gov]

Hi Mike,

The base version of Nek is not ready to simulate chemically reacting
flows. What are the fits and gaps?

Fits:
- Low Mach number formulation to deal with density varying flows
- Accurate splitting formulation to segregate the hydrodynamic
sub-system (momentum+continuity eqn) and the thermochemical sub-system
(energy and species eqn)
- Interface to CVODE (a high order integrator to solve the stiff
thermochemical sub system efficiently)

Gaps:
- Routine to compute the RHS (needed input for CVODE)
- The routine to compute the thermal divergence does not include the
species eqns
- Routines to compute the thermophysical and kinetic properties

I developed a plug-in to do reactive DNS using Nek  when I was a PhD
student at ETH Zurich. It performed really well and we did some pretty
impressive simulations at the time
(http://nek5000.mcs.anl.gov/index.php/Visualization_Gallery). I am
afraid the plug-in is not available for the public :(

Cheers,
Stefan

On 7/28/11, nek5000-users at lists.mcs.anl.gov
<nek5000-users at lists.mcs.anl.gov> wrote:
> Hi Mike,
>
> Here are the .rea and .usr files of a case I did with 2 reacting scalars.
> The files are modified versions of the rayleigh case from repo that
> simulates the Boussinesq equations, but I turned off the buoyancy term and
> added a second scalar with reaction.
>
> In the userq routine in the .usr file, the qvol term specifies scalar
> production due to reaction.  The first scalar is called temp.  The next ones
> are ps(1), ps(2), etc.  The conditional statement (ifield.eq.2) specifies
> production of temp, the (ifield.eq.3) statement specifies production of
> ps(1).
>
> The README of the shear4 example from repo, which has 4 passive scalars,
> describes how you can change the parameters relating to the multiple
> scalars.
>
> hth,
>
> David
>
>
> On Thu, Jul 28, 2011 at 2:57 PM, <nek5000-users at lists.mcs.anl.gov> wrote:
>
>> All,
>>
>> I'm interested in using Nek for simulation of reacting flows.  Can anyone
>> send me, or point me towards, a simple example that could get me going?  I
>> guess I'm most interested to see the details of storage/operation with
>> passive scalars.
>>
>> Thanks.
>> --Mike
>>
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>