[marwane cherkaoui]

Hello everyone,

I’m working with ANSYS Fluent 19.2 to study the microclimate inside an agricultural greenhouse.
My computational domain includes the outdoor environment, the greenhouse, and vegetation blocks.
I have implemented a UDF to model plant transpiration, and I believe it works properly.

However, I’m facing an issue: in the outdoor domain, the relative humidity reaches up to 700 %, which is physically unrealistic. Inside the greenhouse, the values are normal.

I’m using the Species Transport model for water vapor and the DO (Discrete Ordinates) model for radiation, with the Solar Calculator enabled.
In the DO model, I defined two spectral bands:

Band 0: from 0.4 to 2.4 µm (solar spectrum)

Band 1: from 2.4 to 100 µm (thermal infrared)

For the outdoor boundary conditions, I set the temperature to 298 K and the absolute humidity to 0.0119 kg/kg of dry air, which should correspond to a relative humidity of about 58 %.
However, Fluent gives an outdoor relative humidity of around 700 %, which is completely inconsistent.

If anyone has faced a similar issue or has suggestions (possible error in the DO setup, unit mismatch, or Species Transport configuration), I would really appreciate your help.

Best regards,