Default boundary conditions

[Cocytus-kyon]

Hi,

I couldn't find the content about the default transport boundary conditions in the manual.

For example, in section 2.9 of "FEHM_VERIFICATION", Test of Barometric Pumping Mechanisms，the model did not set the transport boundary of the surface. Is it set to zero solute-flux boundary by default?

What is the default processing method for FEHM if I do not set any boundary conditions for transport.

Looking forward to your reply.
Thank you!