Problem with parabolic - "Need a better guess y0 for consistent initial conditions."

I experience the problem with function "parabolic": T=parabolic(T_old,[0 dt],bl,p,e,t,'x',0,q.*x,'x'); when trying to solve nonlinear heat equation problem in command line. When T_old~=0 and dt<0.0005 the error occured and this message appeears: "Error using daeic3 (line 231) Need a better guess y0 for consistent initial conditions.

Error in ode15s (line 314) [y,yp,f0,dfdy,nFE,nPD,Jfac,dMfac] = daeic3(odeFcn,odeArgs,tspan,htry,Mtype,Mt,Mfun,...

Error in parabolic (line 232) [t,uu]=ode15s('pdeprbf',ttlist,uu0,options); %#function pdeprbf

Error in teploprovodnost (line 19) T=parabolic(T(:,2),[0 dt],bl,p,e,t,'x',0,q.*x,'x');"

What is this may be connected with? I can't find this type of errors anywhere.

Answer 1

[Bill Greene]

Rusian,

Unfortunately, the current version of PDE Toolbox does not support nonlinear transient equations. The function parabolic can not solve heat transfer equations where the coefficients or boundary conditions are functions of temperature.

Regards,

Bill Greene

[Ruslan]

I don't use the temperature in coefficients and boundary conditions.

Furthermore I succeeded in solving this equation with another mesh, greater than one I tried to use. So the problem is connected with the mesh.