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Torsten
Posts:
1,488
Registered:
11/8/10


Re: Third order nonlinear boundary value problem
Posted:
Mar 28, 2014 9:51 AM


"Rachel " <racheldore20@hotmail.com> wrote in message <lh3pjc$g23$1@newscl01ah.mathworks.com>... > Hey Torsten, > > Thanks so much for that but I'm really confused I am trying to solve numerically for the velocity profiles of the fluid from the boundary layer equations, > > udu/dx+vdu/dy=Udu/dx+nud^2u/dy^2 > > du/dx+dv/dy=0 > > (These derivatives are partial apart from the 3rd term in the first equation). > > The boundary conditions are du/dy=0(partial) when y=0 and u=0 when y=+infinity. > > I introduced the stream function u=d(stream)/dy and v=d(stream)/dx (both partials) > > where stream function is a similarity solution, stream=x^pf(y/x^q) where eta=f(y/x^q). > > Putting the boundary layer equations in terms of the stream function and having found p=1/3 and q=2/3 the equations reduce to f'''+1/3ff''+1/3f'^2 now i thought the boundary conditions changed to f(0)=f''(0)=0 and f'(infinity)=0. > > Is there any sense in trying the code with the first set of boundary conditions or would there be a way of solving the PDE's maybe?? I'm clueless with all this. > > I solved the ODE analytically using the first set of boundary conditions. > > I don't know if this will make much sense to you but it would be great if you could let me know!! Your very good thanks. > > Rachel
Is it Blasius' equation you are trying to solve ? http://en.wikipedia.org/wiki/Blasius_boundary_layer
Best wishes Torsten.



