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-   -   why laplacian() failed (http://www.cfd-online.com/Forums/openfoam-solving/72147-why-laplacian-failed.html)

OFCrash January 27, 2010 06:24

why laplacian() failed
 
Hi guys im a newbie, i got a problem wired well..

i have 2 equations:
dT/dt=1/a*(div(b*grad(T)+div(c*grad(wl))) (1)
dwl/dt=1/d*(div(e*grad(T)+div(f*grad(wl))) (2)

a--f are functions of T and wl

so i give my solver here
fvm::ddt(T) (1)
==
1/a*fvm::laplacian(b,T)+1/a*fvc::lapalacian(c,wl)

fvm::ddt(wl) (2)
==
1/d*fvc::laplacian(e,T)+1/d*fvm::lapalacian(f,wl)

my ideas here is to separate the T and wl, so in (1)
"wl" is considered as known(fvc::) and in (2) "T" is
considered as known(calculated from 1).

problem: the solver is compiled without errors and
it works but the results staye as initial conditions,
the "T" ad "wl" i got didnt change, they are around
the initial conditions and no convergence at all even
run longtime. it seems laplacian failed when reading
bundary conditions.

note: scheme of laplacian is linear corrected
scheme of ddt(T) backward
mesh:1D
initial condition: uniform
bundary condition:timeVaryingUniformFixedValue

thanks for all of your advices welcom~~

OFCrash February 1, 2010 08:32

i tried another solver here
fvm::ddt(T) (1)
==
b/a*fvm::laplacian(T)+c/a*fvc::lapalacian(wl)

fvm::ddt(wl) (2)
==
e/d*fvc::laplacian(T)+f/d*fvm::lapalacian(wl)


this time the T and wl are resolved but the results of
T and wl are not good well, coz we couldnt get the
coeff "bcef" out of laplacian() if the "bcef" depend on
the T and wl.

so any1 have some ideas ?


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