Setting a B.C using UserFortran in 4.3
 

Hi, Everyone.

I am trying to set a boundary condition of log velocity distribution at inlet. I use USRBCS routine for it and referd the Solver Manual(10.6.2). However error messages come and then solver stops. The messages are:

Solver | runsolve4: Compiling user Fortran...

Solver | f90: Warning: ../fort/zzz000.f, line 185: This statement function has not been used. [IP]

Solver | IP(I,J,K)=IPT((K-1)*ILEN*JLEN+(J-1)*ILEN+I)

Solver | ------^

Solver | f90: Warning: ../fort/zzz001.f, line 185: This statement function has not been used. [IP]

Solver | IP(I,J,K)=IPT((K-1)*ILEN*JLEN+(J-1)*ILEN+I)

Solver | ------^

Solver | f90: Warning: ../fort/zzz002.f, line 185: This statement function has not been used. [IP]

Solver | IP(I,J,K)=IPT((K-1)*ILEN*JLEN+(J-1)*ILEN+I)

Solver | ------^

Solver | runsolve4: Creating executable, please wait...

Solver | ld:

Solver | obj/zzz000.o: usrbcs_: multiply defined

Solver | obj/zzz001.o: usrbcs_: multiply defined

Solver | obj/zzz002.o: usrbcs_: multiply defined

Solver | f77: Severe: Failed while trying to link.

Solver | runsolve4: Failed to link CFX-4.

Solver | runsolve4: Job completed

Solver | An output file was not produced

Solver |

Solver | Finished.

I don't change any parts exept UserArea5. Does anybody give me advice for resolving this problem?

Thanks.

Re: Setting a B.C using UserFortran in 4.3
 

I would be a help if you posted the important changes you have made in Userarea5.

Regards Jan

Combustion model in CFX
 

Hello to everybody, I am a new user of CFX4.4, and I am using this software for gaseous combustion simulation. I used EBU combustion model and with another run of CFX I used the options of CHEMICAL REACTIONS to specify kynetic parameters. In the last simulation I got a value of fuel conversion higher than that obtained with EBU. I was surprised as EBU was based on infinitely fast reaction and so limitations came only by mixing. I hope someone will help me. Thank you.

Re: Combustion model in CFX
 

How do you calculate the fuel conversion? Are you very sure that both solutions are converged, have you checked your input file, so the "heat of fuel" is the same in both cases. Try to restart your calculations on the old dump file with the option "Iteration on Hydrodynamic equations" set to zero. This will force the solver only to solve species and enthalpy equations, an improve the solution. It is actually a very good approach in all cases where heat transfer is involved.

Regards Jan

Re: Setting a B.C using UserFortran in 4.3
 

Hello. Thanks your reply. What I made change in USRBCS are:

1. The value IUSED=0 to 1.

2. The name of arguments,variables and formula in UserArea5.

In Solver manual (10.6.2), for instance, T and IT are used in GETVAR. I just replaced IT,T with IU,U as x-component velocity. All I did in UserArea5 were that kinds of things.

Thanks, tokai

EBU and EDC
 

I would like to know more about EDC model implemented in CFX, as I found different EDC models, such as Magnussen,Hjertager(1976), and Magnussen (1981) and Magnussen (1989). I hope someone will give me any suggestion

Re: EBU and EDC
 

what does EDC model,could you please explain in brief.

thanks for you time.

Regards joseph

Re: EBU and EDC
 

EBU is the so called eddy break up, while EDC is eddy dissipation concept. These two theory about combustion where developed by Spalding and Magnussen respectively, but I believe that the model implemented in CFX as EBU is the EDC.

Re: EBU and EDC
 

That would be strange, I dont have acces to CFX just now, but I am sure your are wrong. The difference between the EBU and EDC are not so great, under special conditions the EDC (equations) degenerates into the EBU equations.

Regards Jan

Re: EBU and EDC
 

I would be very glad if you tell me which are the conditions for which EDC degenerates in EBU.

Re: EBU and EDC
 

Hi'

I do not have the EDC papers with me (on holiday), but as far as I remember then there is a fraction for the reaction in the small structures in the EDC, and not in the EBU. If this fraction is equal to one then EDC becomes similar to EBU.

I am not sure about this, but I will check it later when I find my papers.

Jan