Hi, I'm currently working on a system of PDEs using the Coefficient Form PDE module in 2D for my reactor design coursework. My system requires the coupling of multiple dependant variables with different units, which I did by specifying multiple coeffcient form PDEs under the component. Based on my formulation, I do not wish to impose any boundary conditions on some of the dependant variables (I'm rather new to FEM and I'm not sure if this is allowed), However, I realised that COMSOL imposes a default boundary condition on boundaries for all dependant variables under each coefficient form PDE node.
Based on this problem, I would like to ask if there is a way to not impose a boundary condition for certain dependant variables, if it is allowed. I an currently thinking along the lines on setting the constraint to zero buy I'm not sure of its the right thing to do. Any help would be much appreciated, thank you.