Biginner in FDS

[gforney]

Hi am runing the basic exemple called pressure_boundary and according to 
the user guide the energy budget is found in a file called 
pressure_boundary_hrr.csv but unfortunately i can't get 
HRR= CONV_LOSS+COND_LOSS. please let me know how to get the energy balance 
right.

furthermore how  can i see the residuals in order to make sure that the 
simulation has reached an appropriate convergeance criteria?

Regards

Original issue reported on code.google.com by bigzakk on 2010-05-04 13:48:05

[gforney]

Submit a very simple case that demonstrates the problem. 

FDS is not like conventional RANS CFD models. Read the Tech Guide for more 
description of the basic algorithm.

Original issue reported on code.google.com by mcgratta on 2010-05-04 14:10:49

[gforney]

Hi thanks for your reply. actually the case am talking about is the exemple 
case:pressure_boundary in page 86 of the user guide. I dont think its a problem I 
just have issues understanding whats going on. Thanks

Original issue reported on code.google.com by bigzakk on 2010-05-05 07:42:45

---

• _Attachment: pressure_boundary.fds_

[gforney]

What do you feel is not working correctly?  
HRR = heat release of fire
CONV_LOSS = energy flow due to mass flow at the boundaries
COND_LOSS = energy loss to SOLID walls (not open boundaries)

There isn't a specific accounting of radiation loss through an open boundary (it is
part of RAD_LOSS but that also includes solid walls).  

Which leads to a question, should QRAD at open boundaries be tallied in one of these
(or a new) quantities?

Original issue reported on code.google.com by drjfloyd on 2010-05-05 14:16:32

[gforney]

your reply has been really helpfull... just as a general question how does FDS set 
the convergeance criteria in the momentum equation and other equations as well ?
what is the easiest way to calculate boundary fluxes ( net heat at 
boundaries ) ? ..thanks

Original issue reported on code.google.com by bigzakk on 2010-05-06 17:18:38

[gforney]

FDS is not like a RANS model where one iterates to a solution at each time step to 
within a given tolerance. It is an explicit time-marching scheme, second-order 
accurate in space and time. Read more in the FDS Tech Guide.

Original issue reported on code.google.com by mcgratta on 2010-05-06 17:28:47

[gforney]

thanks a lot.... you guys have been really great

Original issue reported on code.google.com by bigzakk on 2010-05-07 09:03:06