Hello, I am using the Coefficient form of PDE and I need to set a boundary at a concentration value of 1[mg/cm^3].
When the simulation runs, This concentration will spread uniformly throughout the geometry.
I do not want the inlet boundary set at a constant concentration 1[mg/cm^3] it should reduce over time as the diffusion causes the concentration to be distributed evenly across the entire geometry.
I want to know how can I set the value to my boundary without using Dirichlet boundary conditions. Dirichlet boundary conditions will keep the value of concentration at the boundary constant. I do not want it constant. I want it reducing as it loses the mass due to diffusion towards region of lower concentration.