scalar flux boundary condition

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 May 21, 2003, 21:56 scalar flux boundary condition #1 Murali Guest   Posts: n/a 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 ?

 May 22, 2003, 07:49 Re: scalar flux boundary condition #2 John Guest   Posts: n/a 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.

 May 22, 2003, 14:18 Re: scalar flux boundary condition #3 Murali Guest   Posts: n/a 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/

 May 23, 2003, 06:28 Re: scalar flux boundary condition #4 John Guest   Posts: n/a 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.

 May 23, 2003, 11:50 Re: scalar flux boundary condition #5 Murali Guest   Posts: n/a John, wonderful. thanx a lot. Regards Murali

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