The equation is left unsolved, but that is not a big deal. Thanks everyone for insights, it will be helpful in future, because I will try to solve some other similar equations.
Thanks. I tried Laplace transform L[U(x,t)]=V(x,s) and got:
Vxx-s/D*V=0
sorry for my bad writing of formulas, i am new at LaTeX.
With problematic boundary condition getting form
V(0,s)=A(s)
The problem is boundary condition that is time dependant:
U(0,t)=a(t)
With constant boundary condition i get analytical solution relatively easy, but with time dependant boundary condition i always get that some of the integration constants are functions of t which is not right
Lets say...
November 2020 does have diffusion equation problem, but i do not know how to use any of information there to solve my problem. Soluton on picturem from the book is the case that mostly resembles my problem, but again i need boundary condition U(L,t)=b(t), instead i have flux that equals zero at...
Standard method of separation by variables does not match up nicely with boundary conditions. I have seen methods for solving inhomogeneous heat equation using green functions, but that again failed, because it required knowledge of U(L,t) which was not given by any condition
U=U(x,t)
Ut=DUxx; 0<=x<=L, t>0
U(x,0)=0 0<x<=L
U(0,t)=a(t); t>0 *a(t) is known function*
(dU/dx)=0 for x=L
I have looked into many ways but not one is usable for diffusion equation with this boundary conditions.