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-   -   air flow simulation in double skin facade with openfoam (https://www.cfd-online.com/Forums/openfoam/83215-air-flow-simulation-double-skin-facade-openfoam.html)

 gygfei December 20, 2010 04:59

air flow simulation in double skin facade with openfoam

hello all:

i am trying to simulate air flow in the double skin facade,which is kind of popular facade style now ,it is made of 2 layers of glazing with cavity inbetween,air inlet and outlet at the bottom and top seperately. this kind of structure could make air in the cavity heat by solar radiation and remove heat out of this box by buoyancy.
now i build a box model with bottom inlet and top outlet,using buoyantSimpleRadiationFoam.it works but the results are a little bit weird,i am expecting an air induction in the inlet and air flow-out in the outlet,but results shows a air-circulation from top to bottom and bottom to topin the cavity,no suction in the inlet.
i still have some problems to set the boundary conditons:
1.i need to set a heatflux on external glazing to simulate solar radiation, but the wallheatflux utility seems doesn't work here,error accurs .
2.how could i set other boundary like pd and p in such natural convection case? now for p,it is zeroGradient for both inlet and outlet,for pd,it is fixedFluxbuoyantPressure.

final results like this,there seems a convergency problem on pd.

Time=545
ux,initial residual=xxxe-5,final residual=xxxe-6,no inerations 2;
uy,initial residual=xxxe-5,final residual=xxxe-6,no inerations 2;
uz,initial residual=xxxe-5,final residual=xxxe-6,no inerations 1;
h,initial residual=xxxe-5,final residual=xxxe-6,no inerations 0;
G,initial residual=xxxe-6,final residual=xxxe-6,no inerations 0;
pd,initial residual=xxxe-5,final residual=xxxe-7,no inerations 113;
epsilon,initial residual=xxxe-5,final residual=xxxe-6,no inerations 2;
....

i don't know how to push it forward now, any help would be appreciated.

 gygfei December 20, 2010 05:50

i define one of boudary conditions by wallHeatFlux like this:

extGlaz
{
type wallHeatFlux;
heatFlux uniform 312.0;
}
....

but when i run it,error note as followed:

can't find "value"entry on patch extGlaz of field T in file".....",which is required to set the values of the generic patch field.(actual tyep wallHeatFlux"
please add the "value' entry to the write function of user-defined boudary-condition or link the boudary-condition into libfomaUtil.so

can anyone tell me,what is the problem?

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