Formulation of a tricky PDE for pdenonlin or pdetool

Hello everyone,

i am trying to implement a mathematical method in my work. Since my profession is biotechnology and not mathematics i am struggling. I will hopefully solve this problem in a future seminar but until then i would like to find out if i have to care about discretization using the method provided (work from S.Berres et al. 2005 Chem. Eng. J.) or if it is possible to use e.g. pdenonlin in a simple way. The equation describes the change of concentration inside a tube during centrifugation (c..concentration, t...time, r...one dimensional spacial variable (radius), w..angular velocity, f..flux function, A...primitive of diffusion coefficients, g..constant,u..constant) where c=c(r)

dc/dt=d^2(A(c))/dr^2+d(w^2*r/g*f(c))/dr

A and f are 0 for special intervals of c and in the other cases f=constant0*(1-c)^(constant2) and A=constant1*int((1-c)^(constant2)*(c/constant3)^(constant4-1)-1),c=0..c(r))

so i do not have a simple expression like in the tutorials e.q d^2T/dx^2 but instead a function like d^2A(c)dr^2.

Can anybody give me a hint how to deal with that ? Is it possible to do this the easy way ?

So my goal would be to formulate the given PDE in a way, that pdenonlin can handle it.

Thank you in advance

M.