scalar flux boundary condition
 

<font face = "arial">Does anybody know how to specify the following boundary condition ?


dq
flux = -D---- = q^0.5
dx



where q is a user-defined scalar. Any idea which user-subroutine is to be used and how ?

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Re: scalar flux boundary condition
 

Define the wall region where you want to specify the species flux as constant flux region and use user code bcdefw to change the flux according to solution.

Re: scalar flux boundary condition
 

<font face = "arial">Hello John,

nice suggn. Thanx. The subroutine BCDEFW requires me to RETURN the value of SCALAR(IS). Are you suggesting that if I have the previous boundary condition, I specify a constant flux say A close to te value of q^0.5 ? i.e.
dq
flux = -D---- = q^0.5 = approx A where A is a constant
dx


So if I specify A as the constant flux, I would then correct it to the required flux using a finite difference expression, involving the values at the centre of the adjacent cell and value at wall ??? i.e.Since,
SCALC(IS) - SCALAR(IS)
flux = -D ---------------------
deltax


does that mean,

SCALAR(IS) = SCALC(IS)+flux*deltax/D ? Are you suggesting I iterate on this value locally ?

Regards
Murali

http://groups.yahoo.com/group/fuel_cells/
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Re: scalar flux boundary condition
 

Since you already know A, just put A in whichever scalar, say:

IF(IREG.EQ.1) THEN scalar(1)=a endif

SEE nom.inc file in ufile directory because for BCDEFW, scalar is either mass fraction or its flux depending on what boundary condition you specified in prostar.

Re: scalar flux boundary condition
 

John,

wonderful. thanx a lot.

Regards Murali