[Getdp] result all zero

Lin Ji jil at rpi.edu
Fri Oct 26 19:31:03 CEST 2001


Hi, Christophe,
    I am not trying to solve the original wave equation in frequency domain.
I am solving the Helmholtz equation
        u_xx + u_yy + (\tau^2 / c^2)u = 0
directly where the subscript _xx denotes the 2nd partial derivative to x and
\tau corresponds to a specific frequency. I had the following formulation for
the above equation:

Formulation {
  { Name hhltz; Type FemEquation;
    Quantity {
      { Name u; Type Local; NameOfSpace Hgrad; }
    }
    Equation {
      Galerkin { [ tau_c*tau_c/mu[] * Dof{u} , {u} ];
                 In Omega; Integration I1; Jacobian JVol;  }

      Galerkin { [ -Dof{d u} , {d u} ];
                 In Omega; Integration I1; Jacobian JVol;  }

      Galerkin {  [ f_bc[] , {u} ];
                 In Gamma_f; Integration I1; Jacobian JSur;  }
    }
  }
}

where mu[] = c^2 and tau_c denotes the central frequency and f_bc[] is the
Neumann boundary condition. They are all defined in the Function object.

Thank you for your work and also thank Andre Nicolet for referring the
website.

Lin Ji

-- 
Dept. of Math., RPI
518-276,6904 (work)