Need help on Modeling Adsorption

Hi all,
I hope you are doing well. I tried to use FEATool to model the adsorption as in the link below. As in the video, the guy used Matlab as well. Let me briefly explain the issue. For the concentration equation, I can use the Convection Model in the FEATool; however, I need "q" to link to "c". I added the custom equation in FEATool; however, the equation will require the boundary conditions. As you can see in the video, q does not have a boundary condition at all. I tried to put the q values at boundaries = q* - (ap/3/kf)*q'. However, the system couldn't be solved. I hope you can help. Thank you.


https://www.youtube.com/watch?v=aPYMeChRUE0&ab_channel=RahmatSunarya

Hi, anyone can help? Thank you

You seem to want to add an ODE as a coupled boundary condition, this is not supported by the current built-in functionality. Possibly you could maybe to this as a custom/user-defined function where in the Matlab function you would manually solve the ODE for q

https://featool.com/doc/physics#phys_coef_user