If this node is selected from the Pairs menu, choose the pair on which to apply this condition. A pair has to be created first. See
Identity and Contact Pairs in the
COMSOL Multiphysics Reference Manual for more details.
The equation for this condition is 
, where
is the prescribed relative humidity on the boundary. For
User defined, enter a value or expression for the
Relative humidity 
. The default value is 0.5. Else, select an
Ambient relative humidity defined in an
Ambient Thermal Properties node under
Definitions.
To display this section, click the Show button (
) and select
Advanced Physics Options. Select the
Use weak constraints check box to replace the standard constraints with a weak implementation.