Transport equation solver

[gforney]

Hello

I want to solve an additional transport equation for the "CO"
concentration. In FDS5, with which subroutine I have to deal with to do so.
I have own subroutine to compute the source term. Now I need to know how
and where I have to incorporate this source term to solve the transport
equation for CO.  
Thanks in advance.

Regards, Faroque

Original issue reported on code.google.com by liton96101 on 2008-04-07 08:44:14

[gforney]

It is not that simple. CO production and combustion are treated differently, 
depending on whether you have a mixture fraction formulation or whether you are 
using finite rate chemistry. In the latter case, all species are specified 
explicitly via the SPEC namelist group, and the reactions are explicitly defined via

arrhenius parameters. For the mixture fraction, much of the CO logic is hardwired at

the start of the calc and it would be very difficult to explain all of it here. If

you want to work with the source code, you will have to do alot of work just to 
understand how it all works. There is no "plug-in" feature for species transport.

Original issue reported on code.google.com by mcgratta on 2008-04-07 11:26:51

• Labels added: OpSys-All, Application-FDS

[gforney]

Thanks for you reply. 
I was thinking there would be a straight-forward method. Now I have to go thu all the
source codes. Can you please give me a idea/steps how to proceed. For me, the source
term for the transport equation is known (let's say). Therefore I don't need any
combustions to be considered. 
Thanks.

Original issue reported on code.google.com by liton96101 on 2008-04-08 11:08:19

[gforney]

If you want to control the CO production yourself, specify
&SPEC ID='CARBON MONOXIDE' /
&SURF ID='FIRE',HRRPUA=...,MASS_FLUX(1)=...,RAMP_MF(1)='...' /
&REAC C=...,H=...,...,CO_YIELD=0. /
&MISC ..., CO_PRODUCTION=.FALSE. /
This tells FDS to use the default mixture fraction model, but assume that the 
combustion produces no CO, and that you do not want any CO production model turned

on. Then you specify your own CO production rate via MASS_FLUX and the corresponding

ramp. 

Original issue reported on code.google.com by mcgratta on 2008-04-08 12:24:15

[gforney]

Could you please specify the variable name in the MASS_FLUX sub-routine that contains
the value of CO production rate. This must be a 1D vector of length equal to the
number of cells available. 

Thanks in advance.

--
Faroque

Original issue reported on code.google.com by liton96101 on 2008-04-29 11:18:21

[gforney]

It's not in that routine, and it is not a 1D vector.  Have you tried grepping the 
code for CO_PRODUCTION?  Try looking in fire.f90 where the combustion routine is.

Original issue reported on code.google.com by drjfloyd on 2008-04-29 12:55:53

[gforney]

Hello

I found the following line in fire.f90 file
around line no 635

IF(CO_PRODUCTION) THEN
Z_2=YY(I,J,K,I_PROG_CO)
...
...

is this variable YY(I,J,K,I_PROG_CO) contains the CO production by COmbustion model.

Thanks in advance.

Faroque

Original issue reported on code.google.com by liton96101 on 2008-06-22 15:52:32

[gforney]

Hello

I found the following line in fire.f90 file
around line no 635

IF(CO_PRODUCTION) THEN
Z_2=YY(I,J,K,I_PROG_CO)
...
...

is this variable YY(I,J,K,I_PROG_CO) contains the CO production by COmbustion model.

Thanks in advance.

Faroque

Original issue reported on code.google.com by liton96101 on 2008-06-22 15:53:38

[gforney]

Yes -  this is Z2, the second of three mixture fraction variables that are described

in the Tech Guide.

Original issue reported on code.google.com by mcgratta on 2008-06-22 16:04:09

[gforney]

Thanks for the reply.
Now, If I re-arrange the above code as follows:

IF(CO_PRODUCTION) THEN
YY(I,J,K,I_PROG_CO) = XX(I,J,K)

Z_2=YY(I,J,K,I_PROG_CO)
...
...

where, XX is a variable which contains the CO production (say computed by me). Do you
think this assignment would be logical or consistence. 

Regards, 
Faroque 

Original issue reported on code.google.com by liton96101 on 2008-06-23 08:41:36

[gforney]

Z_1,Z_2, and Z_3 are all coupled.  You cannot arbitrarily change one without first 
accounting for the effects of that change in the values of the other variables.

Original issue reported on code.google.com by drjfloyd on 2008-06-23 12:30:18

[gforney]

You need to understand EXACTLY what Z_2 is. It is NOT the mass fraction of CO, but 
rather the mass fraction of CO plus other combustion products that are generated 
along with it. If you do not fully understand this model, then I think your results

will not make sense. Do not assume that you can just change one line of code and 
make the new model consistent with the old.

Original issue reported on code.google.com by mcgratta on 2008-06-23 12:32:25