Summary

Boundary conditions

Now that we have taken care of the symmetry planes, we have to specify the boundary conditions at these planes. We have to tell gd1 what conditions are to be applied at the six planes x=xlow, x=xhigh, y=ylow, y=yhigh, z=zlow, z=zhigh. The possible values are: electric boundary conditions, magnetic boundary conditions, and periodic boundary conditions. For our problem, we only need electric and magnetic boundary conditions. We specify these conditions again in the section "-mesh". We edit our inputfile such that the entries for -mesh now look like:

 ###
 ### We define the borders of the computational volume,
 ### we define the default mesh-spacing,
 ### and we define the conditions at the borders:
 ###
 -mesh
     spacing= eval(InnerRadius/15)
     pxlow= eval(-1.1*OuterRadius)
     pylow= eval(-1.1*OuterRadius)
     pzlow = eval(-(GapLength/2+TaperLength+9e-2))
     pxhigh= 0
     pyhigh= 0
     pzhigh= 0

     #
     # The conditions to use at the borders of the computational volume:
     #
     cxlow= electric, cxhigh= magnetic
     cylow= electric, cyhigh= magnetic
     czlow= electric, czhigh= electric

We are not done yet: Since gd1 can compute resonant fields and time dependent fields, we have to specify what kind of field we are interested in. We want to compute resonant fields, so we specify this by entering at the end of our inputfile:

 -eigenvalues
    solutions= 15      # we want to compute with 15 basis vectors
    estimation= 10e9   # the estimated highest frequency
    doit

When we feed gd1 with this inputfile (gd1 $<$ doris03.gdf), gd1 complains about an IO-error:

 *** A component of the path prefix does not exist or the Path parameter points
 *** to an empty string.
 CreateDirectory: cmd: mkdir /tmp/--username--/--SomeDirectory--/Results
  error code: 2
 ** cannot open catalogue: iostat: 14
 ** catalogue: "/tmp/--username--/--SomeDirectory--/Results/catalogue"
 ** error msg: "No such file or directory / permission denied"
 InitializeDatabase: cannot read catalogue.. iostat: 14
 *** check "outfile" in section "-general"..
 *** errors in settings
 *** Since this not seems to be an interactive session,
 *** I decide to treat this as a fatal error.
 *** Fix the input.
 stop

We have not yet specified where the results of your computation shall be written to! We do this by editing our inputfile:

 ###
 ### We enter the section "-general"
 ### Here we define the name of the database where the
 ### results of the computation shall be written to.
 ###    (outfile= )
 ### We also define what names shall be used for scratchfiles.
 ###     (scratchbase= )
 ###
 -general
    outfile= /tmp/bruw1931/garbage/doris
    scratchbase= /tmp/bruw1931/garbage/doris-scratch