[Getdp] Time-dependent constraints

[Rasilo Paavo]

Hi,

I have a question on time-dependent constraints...
I'm dealing with a 3-D magnetic vector potential formulation for eddy-current simulations.

As a source, I'm trying to set the vector potential on one boundary surface (SourcePhi) to be a gradient of a known scalar function phi[].
Function phi[] is defined as a list of values in the nodes of the surface.
The following works well in a static case:

******************************************************************
Function {
  listphi = ListFromFile["phi.txt"];
  phi[] = ValueFromIndex[]{listphi{}};
}

Constraint {
  { Name SourcePhi ; Case { { Region SourcePhi ; Value phi[] ; } } }
}

FunctionSpace {
  { Name Hcurl_a ; Type Form1 ;
    BasisFunction {
      { Name se1 ; NameOfCoef ae1 ; Function BF_Edge         ; Support Core ; Entity                EdgesOf[ All , Not SourcePhi ] ; }
      { Name se2 ; NameOfCoef ae2 ; Function BF_GroupOfEdges ; Support Core ; Entity GroupsOfEdgesOnNodesOf[ SourcePhi           ] ; }
    }
    Constraint {
      { NameOfCoef ae2 ; EntityType NodesOf ; NameOfConstraint SourcePhi ; }
    }
  }
}
******************************************************************


Next, I'd like to make a transient simulation with phi[] defined similarly for each time step separately.
However, the following does not seem to work:

******************************************************************
Function {
  // Lists for each time step
  listphi_0 = ListFromFile["phi0.txt"];  phi_0[] = ValueFromIndex[]{listphi_0{}};
  listphi_1 = ListFromFile["phi1.txt"];  phi_1[] = ValueFromIndex[]{listphi_1{}};
  listphi_2 = ListFromFile["phi2.txt"];  phi_2[] = ValueFromIndex[]{listphi_2{}};
  // etc..

  // Source function
  phi[] = ($TimeStep==0) ? phi_0[] :
          ($TimeStep==1) ? phi_1[] : 
          ($TimeStep==2) ? phi_2[] :
  // etc..
}

Constraint {
  { Name SourcePhi ; Case { { Region SourcePhi ; Value 1. ; TimeFunction phi[] ; } } }
}
******************************************************************

>From that, I get an error message "Unknown Entity Index (0) in ValueFromIndex Table".

Is it so that the function used as the TimeFunction cannot be coordinate-dependent?
Even X[] and Y[] inside the function do not seem to work.

Is there any other way to impose such a boundary condition on each time step separately?

With best regards,
Paavo Rasilo

--
Aalto University School of Electrical Engineering
Espoo, Finland