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 Murali May 21, 2003 21:56

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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 John May 22, 2003 07:49

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.

 Murali May 22, 2003 14:18

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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 John May 23, 2003 06:28

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.

 Murali May 23, 2003 11:50

Re: scalar flux boundary condition

John,

wonderful. thanx a lot.

Regards Murali

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