[marsa27]

Hi,
I want to simulate the thermal radiation emitted by a UV lamp. I would interested to use a spctral model to select only the wavelenght interested. What is the model to use? Is correct to use a P1 model and to use the multiband to create the corresponding band?
Thank you

[ghorrocks]

The P1 model is used for optically thick materials, that is where the radiation does not penetrate far so optical path calculations are not required. Are you sure this model is what you want?

The CFX documentation describes the available options for multiband radiation modelling.

[Opaque]

Not sure how can the model be solved for a single spectral wavelength, unless the software manages the other ones behind the scenes.

You should at least discretize the spectrum into 3 bands:
1 - from lowest meaningful wavelength -> UV band lower limit
2 - UV band lower limit -> UV band upper limit
3 - UV band upper limit -> maximum meaningful wavelength

The total emission must include all the meaningful wavelengths; therefore, the spectrum must be properly discretized either by the user or the software. ANSYS CFX does nothing behind the scene.

If your spectral discretization is not complete for the temperature range in the problem, the software will trigger a warning about incomplete coverage of the energy spectrum. Try and see.