WUFI

Dear WUFI users

I recently run two identical simulations for a rainscreen ventilated cavity assuming a 50mm air cavity with no additional moisture capacity. The simulations have identical parameters for the build-up, moisture sources etc. except for the air changes sources. In simulation:
1) In simulation 1 I set 50 ACH/h assuming a highly-ventilated cavity
2) In simulation 2 I set 20 ACH/h assuming a slightly-ventilated cavity

The total water content results are very different and simulation 1) provides 127 errors while simulation 2) provides only 20 errors. Simulation 1) should be discarded due to the many errors.

Does someone know why this large discrepancy?

Thank you for your assistance,
Amedeo

Dear Amedeo,

more important than the convergence errors are, that the balances are more or less the same. If they are different, it would be better to check over the model. Did you activate the adaptive time step control in the numeric menu? That may help to reduce errors and enhance the convergence.

The differences in the convergence are probably related to amount of water and humidity which is forming in your cavity. If the RH reaches values close to 100 %, the the convergence becomes more difficult due to dew water.

Christian