0
$\begingroup$

The system contains three nonlinear PDE with initial and boundary conditions.

NDSolve[{D[H[t, x], t] + D[u[t, x], x] H[t, x] + D[H[t, x], x] u[t, x] == 0,
  - D[H[t, x], t] + D[v[t, x], x] (1 - H[t, x]) - D[H[t, x], x] v[t, x] == 0,
  D[u[t, x], t] + u[t, x] D[u[t, x], x] == D[v[t, x], t] + v[t, x] D[v[t, x],x] ,
  u[0, x] == 1, v[0, x] == 1, H[0, x] == 0.5, u[t, 1] == Cos[2 t], 
  v[t, 1] == Cos[t], H[t, 1] == 0.5 Cos[2 t]}, {u, v, H}, {t, 0,  10}, {x, 1, 10}]

But the error I got is shown as:

NDSolve::ntdvdae: Cannot solve to find an explicit formula for the derivatives.

NDSolve will try solving the system as differential-algebraic equations. NDSolve::ndcf: Repeated convergence test failure at t == 0.7337582610498328`; unable to continue.

So, when I try to plot one solution component u[x,t]

Plot3D[Evaluate[u[t, x]], {t, 0, 0.5}, {x, 1, 10}]

I get empty box. Any idea?

$\endgroup$
  • $\begingroup$ sol =NDSolve[...];,Plot3D[Evaluate[u[t, x]] /. sol, {t, 0, 0.5}, {x, 1, 10}] $\endgroup$ – Feyre Sep 9 '16 at 19:03
  • $\begingroup$ Nope, it does not work either.. $\endgroup$ – Meva Sep 12 '16 at 8:11
  • $\begingroup$ Nope, it does not work either.. I still got "NDSolve::ndcf: Repeated convergence test failure at t == 0.7337582610498328`; unable to continue." error.. $\endgroup$ – Meva Sep 12 '16 at 8:24
  • $\begingroup$ That wasn't meant to solve the error, just to allow you to plot to see what's going on. $\endgroup$ – Feyre Sep 12 '16 at 10:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Browse other questions tagged or ask your own question.