<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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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.

<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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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.

John,

wonderful. thanx a lot.

Regards Murali