Chapter 3
Running the solver
Now that we have the mesh file compatible with Nektar++ which will support periodic
boundary conditions, Helm_mesh.xml, and we have completed the condition file,
Helm_conditions.xml, we can run the solver by using the following command:
Task: 3.1
Run the ADRSolver in the directory $NEKTUTORIAL using the command:
$NEK/ADRSolver Helm_mesh.xml Helm_conditions.xml
Note that we have written the mesh in a separate file from the conditions. This is generally
more efficient because it allows reopening just the condition file which is much smaller in size
than the mesh file (especially for large problems). However, we could also have written
both the mesh and the conditions in unique file and used the same command as
above for running the solver (in this case with just one file instead of two as line
argument).
As soon as the file finishes running, we should see the following screen output:
=======================================================================
EquationType: Helmholtz
Session Name: Helm_mesh
Spatial Dim.: 2
Max SEM Exp. Order: 5
Expansion Dim.: 2
Projection Type: Continuous Galerkin
Lambda: 2.5
Forcing func [0]: -(Lambda + 2*PI*PI)*cos(PI*x)*cos(PI*y)
=======================================================================
Writing: "Helm_mesh.fld"
Writing: "Helm_mesh.fld"
-------------------------------------------
Total Computation Time = 0s
-------------------------------------------
L 2 error (variable u) : 0.000159378
L inf error (variable u) : 0.000454467
where the L2 and L inf errors are evaluated against the <FUNCTION NAME="ExactSolution">
provided in the Helm_conditions.xml file. To have a more detailed view on the solver settings
and parameters used, it is possible to use the -v option (which stands for verbose) as follows:
Task: 3.2 Rerun the
ADRSolver with the verbose option:
$NEK/ADRSolver -v Helm_mesh.xml Helm_conditions.xml
The simulation has now produced a final .fld binary file.