[Trilinos-Users] problem computing eigenvalues with Sundance

Andrea Penza pepe.aero at alice.it
Thu Feb 2 13:39:10 MST 2012

Dear all,

I have been trying for days to solve the eigenvalue problem related to
Navier-Stokes equations in primitive variables using Sundance. Here is
the formulation that brings me troubles.

// --------------------------------------------------------
  bool lumpedMass = false;

  BasisFamily L1 = new Lagrange(1);
  BasisFamily L2 = new Lagrange(2);

  Expr ux = new UnknownFunction(L2, "ux");
  Expr vx = new TestFunction(L2, "vx");
  Expr uy = new UnknownFunction(L2, "uy");
  Expr vy = new TestFunction(L2, "vy");

  Expr p = new UnknownFunction(L1, "p");
  Expr q = new TestFunction(L1, "q");

  Expr u = List(ux, uy);
  Expr v = List(vx, vy);  
  // U is the solution of main flow, previously computed:
  Expr U = List(u0[0], u0[1]);
  // Define the new weak form for the operator A:
  Expr eqn3 = Integral(interior, (1/reynolds)*((grad*vx)*(grad*ux) +
(grad*vy)*(grad*uy)) + vx*(U*grad)*ux + vy*(U*grad)*uy +
vx*(u*grad)*u0[0] + vy*(u*grad)*u0[1] - p*(dx*vx+dy*vy), quad2 );
  Expr eqn4 = Integral( interior, (dx*ux + dy*uy) * q, quad2 );
  Expr eqnEig = eqn3 + eqn4;
  // Define the weak form to build the operator M:
  Expr massExpr = Integral( interior, vx*ux + vy*uy + 0.0*q*p, quad2);
  LinearEigenproblem probEig(mesh, eqnEig, massExpr, List(vx, vy, q),
List(ux, uy, p), vecType, lumpedMass);
// -------------------------------------------------------------

The compilation of the whole code ends fine.
Trying to run the executable the system reports this error:

	Sundance detected exception: 

	Throw number = 1

	Throw test that evaluated to true: e==0

	Non-evaluatable expr Sum of Integrals[
	rqc=Integration Region
	[6]            cell filter=MaximalCellFilter
	[6]            quadrature rule=GaussianQuadrature[order=2]
	[6]            watchpoint=[]

 	given to SymbPreprocessor::setupExpr()
	test FAILED

Has anyone the idea of what could be the problem?
Thanks in advance for your support.
Kind regards,


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