Is it possible to apply pdepe for a system of two diffusion equations - if d(u2)/dx = 0

The question is the following. I need to solve a system of two one-dimensional diffusion equations, in which the conductivity for one of the variables is zero (but the conductivity between u(1) and u(2) is nonzero (two-phase medium where the flow goes in one phase and the other acts only as a capacitance). d (u1) / dt = d / dx (F (d (u1) / dx) -f (u1, u2) + S (x, t) d (u2) / dt = f (u1, u2) where f (u1, u2) is the mass transfer between two media. When using pdepe head-on, the answer is: Error using pdepe (line 293) Spatial discretization has failed. Discretization supports only parabolic and elliptic equations, with flux term. Can this somehow be circumvented or do I need to compose my own difference scheme? Thank you

[Torsten]

You'll have to discretize your first equation in space on your own and use ODE15S to solve the resulting system of ordinary differential equations.

Best wishes

Torsten.

[Fyodor Tatarinov]

Do you mention to make the system of equations like dy(i)/dt=f(y(i-1),y(i),y(i+1),t)?

[Fyodor Tatarinov]

Is it possible to set the conductivity for u2 very small instead of manual discretization?