The slave term of internal constraint equation xxxx created by contact pair could not be identified
I am using in Mechanical the steady-state thermal analysis to solve the thermal radiation transport in a system. The only boundary conditions I am using is the temperature and emissivity of an inlet and the emissivity of the walls. For my purposes, only the incident radiation is important, but heat condution not. I can suppress some thermal contacts -but not all of them, because I fear underconstraining my system.
After hours of simulation, I am obtain the following message:
The slave term of internal constraint equation xxxx created by contact pair could not be identified. It is likely that either a displacement boundary condition has been applied directly onto a constraint equation or two or more constrait equations share too many degrees of freedom
I know that it is possible to suppress this constrait equation using APDL commands, but I only obtain in the solution one constraint equation number per try, so I really don't know how many of this equations have problems, and it may take decades to fix them all.
Of course I have checked my connections, but none of them seem too troublesome. Anyone has some suggestions?