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-   -   Heat and Moisture solver - Neumann time varing BC (http://www.cfd-online.com/Forums/openfoam-programming-development/121848-heat-moisture-solver-neumann-time-varing-bc.html)

Ricardo August 6, 2013 10:44

Heat and Moisture solver - Neumann time varying BC
 
I would like to write solver for Heat and Moisture transfer in material, but I have problem with boundary conditions. I am using groovyBC to calculate heat and vapour flux on boundaries, but for moisture field it causes stability problems in results.

I can not find problem, but I am thinking about orders of number, heat gradient is in 1e01 but vapour gradient is in 1e-10

Heat transfer flux is obtained from q=alpha*temperature_difference (alpha values from 5 to 30) temperature difference less then 10 Kelvins.

Vapour flux is obtained from q=beta*partial_pressure_difference (beta about 1e-10, partial pressure difference less than 800Pa)

It works for steady state for Dirichlet and Neuman boundary condition.
Where could be a problem?:confused:

Thanks
Richard

Ricardo August 6, 2013 14:13

Please delete this topic, problem was not in solver...
I used wrong aproximation of sorption curve (dw) in fvm::ddt(dw,F)... and it caused oscilation of solution :)

Thanks
Richard


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