Discussion Forum

Hi

you ave probably a few issues, on I see, is the "orange" color of the "air" material proparties. When you choose library materials you need to carefully check all variables used, are these constants or functions, linear or not ? Specially in your case you need to be sure "air" is using the correct "T" and "pA". As you mix in several physics you have potentil duplicated names in there, to avoid this COMSOL adds the physics "(identifier)" name before the variable. you have a "ht.pA" and might have "spf.pA" (?) but "pA" alone is not defined (try in the Results section to integrate "pA", you will get an error, but not for ht.pA). There fore you must already start to edit your matrial data variable name pA to ht.pA.

For T it's slightly different because its a dependent variable of HT and exist globally as is without the "ht." prefix

Then another point check carefully that your pA and T values are within the valid range of the material data, you get easily outside what is defined by default !! (probably not the case here but is a frequent source or errors difficult to detect on only the results ;)

Finally you have several study cases, there I need some more time to understand what you are doing, as I do not find all variables therein ?
I do not fully catch your model and boundary 9, nor the outlet pressure is it absolute "0" or relative to pA ... check the equations behind but you must really understand all items of your model else, you will not get the results as expected, and these are not always so "easy" to validate/verify by hand calculations

Probably you should restart these from scratch and continue stepwise first one physics.

Main comment start from top of node tree and check carefully the coherence of your model top down before runing a study

--
Good luck
Ivar

Hi Ivar

Thanks so much for your help!

for all those study cases, please ignore them, those were me testing with different solver settings.

as for the pA versus ht.pA issue, yeah I think you are right that may give potenial problems, however I tried to change it into ht.pA but it still cannot solve:(

this may be asking too much, but if you get to see this, could you help changing my settings somehow and make this model run-able? I've started from scratch several times already, including combining the two physics into "conjugate heat transfer" but none of them can give satisfying result:(

and lastly, thanks again for all your help!

best regards
Eric

Hi

check too your initial conditions, do you not think you have p=1[atm] at start ? and is it not your physics that is controlling the pressure in the spf ?

--
Good luck
Ivar

Hi Ivar

Yeah, in fact that's the puzzling part, from the example model file here
www.comsol.nl/showroom/gallery/1448/
they actually set the initial pressure in the fluid to 0 and 1atm in fluid properties, but same settings won't work on mine model... I've also tried changing those to 1atm and P+P.ref respectively, that didn't work either..:(

thanks and best regards
Eric

hello, Luo Shi and Ivar Kjelberg

i'm , PHD in electronic and i'm working a cell solar organic and i did the part optic ( calculating the rate of generation ) but the part electric is difficile. could you give me a model a cell solar organic and I working also by comsol , could you help me for this part( electric ) plz, my email is : fottball2012@gmail.com

thanks you