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<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>To GetDP Users/ FDTD Exper<st1:PersonName w:st="on">ts</st1:PersonName>!:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I am setting up a vector electr<st1:PersonName w:st="on">om</st1:PersonName>agnetic
wave problem with travelling wave boundary conditions on the surfaces of a
cube. <o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The E-field on the boundary is solution of the full vector
Maxwell’s equations for a wave travelling in a general direction (i.e.
not <st1:PersonName w:st="on">norm</st1:PersonName>al to any cube surface)<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>The cube side is a few wavelengths.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>I’m trying a FunctionSpace for Form1, with
BF_Edge basis functions, and a Galerkin resolution. The problems I run into
include:<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>(a) Using a constraint with a TimeFunction that
depends on the corrdinates as well as $Time, does not c<st1:PersonName w:st="on">om</st1:PersonName>pile.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>(b) HarmonicToTime presumes the phase of the field on
the boundary is everywhere the same, so that it works for a standing wave i.e.
for two travelling waves, but not for a single travelling wave. This forces me
to use a Newmark scheme, I think.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>(c) Adding time-dependent terms in NxH and following
the MWE.pro examples reproduces the HarmonicToTime result, (if I did it right).<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>(d) getDP seems to generate the resonant modes of the
cube quite easily with several different boundary conditions. However, a full c<st1:PersonName
w:st="on">om</st1:PersonName>plement of 3D PML layers with R~0.001 does not
remove this resonant behavior. In fact they apparently has no effect.<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>Any suggestions? Or examples? Say <st1:PersonName w:st="on">fr</st1:PersonName><st1:PersonName
w:st="on">om</st1:PersonName> a general 3D waveguide problem?<o:p></o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'><o:p> </o:p></span></font></p>
<p class=MsoNormal><font size=2 face=Arial><span style='font-size:10.0pt;
font-family:Arial'>DavidE</span></font><o:p></o:p></p>
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