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finites differences

#4577  Permalink Top

finites differences

May-20-14 14:25:09

Hello

I'm trying to simulate a simple finites differences scheme applied to the shallow water equation in 1 dimension(x) , where the discretization is only applied to the spatial coordinate x then I let modelica solving the whole system by using it's solvers.
the problem is that the program is runing indefinitly and it doesn't even  show an error message, which bring me to close OMEdit and restart it again.

So can someone please tell me what could be the cause of this kind of problem.


here is the code :

Code:

 

model SVDF



  /********Différences finies****************/

  import Modelica.SIunits;

  //nombre de pas(section)

  parameter Integer n = 32;

  //Longueur du canal

  parameter SIunits.Length L = 32000;



  constant Real g = 9.81;

  

  //vitesse

  SIunits.Velocity V[n + 1](start = fill(0, n + 1));

  //aire d'une section

  SIunits.Area S[n + 1](start = fill(20, n + 1));



protected

  //longueur d'une section

  parameter SIunits.Length dx = 32000 / n;

equation

  for i in 1:n loop

  V[i + 1] * S[i + 1] - V[i] * S[i] + dx * der(S[i]) = 0;

  dx * der(V[i] * S[i]) + V[i + 1] ^ 2 * S[i + 1] - V[i] ^ 2 * S[i] + 0.05 * g * (S[i + 1] ^ 2 - S[i] ^ 2) = 0;



  end for;

//CL

  S[n + 1] = 20;

  V[1] = 0;

end SVDF;

Thank you very much for your answers.

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