Hello, Mr. Steven Johnson and all.
I faced a rather strange beaviour of my system.
I make a 3d simulation of a gaussian wave propagating through silver block with
a periodical holes and measure a transmission spectrum (ctl is included). I
observe following: I fix source and block with holes (thus the distance between
them is always constant), I also fix the distance between block and flux object
which gather spectrum data. After it I change the number of cells in
Z-direction (the direction of wave propagation), one can predict that there
will be the same results however it is not so. If I increase my cell by 1 one
result is obtained and if by two another one. They have rather similar form
but different amplitude and one is shifted in caomparison with another.
I tried to make a bandwith of the source narrower and decrease Courant value
but it did not work.
I wonder what can be wrong here.
Thanks in advance.
Andrew Komvzvoda.
---my ctl----by changing shiftZ and cell_numZ you get different spectral results
-------------
(reset-meep)
(define-param TotalTime 200)
(define-param a 100); cell step
(define-param cell_numX 10)
(define-param cell_numY 10)
(define-param cell_numZ 60)
(define-param pml_width 4)
(set! eps-averaging? false);
(set! Courant 0.33)
(set! geometry-lattice (make lattice (size cell_numX cell_numY cell_numZ)))
(define-param fcen 0.19)
(define-param df 0.4) ;
(set-param! resolution 7)
(define angle 0)
(define kx 0)
(set! k-point (vector3 kx 0 0))
(set! pml-layers (list (make pml (thickness pml_width) (direction Z))))
;; establish periodic boundaries
(set! kx (* fcen (sin (deg->rad angle))))
(change-k-point! (vector3 kx 0 0))
;-------------------------------------------------------------
;geometry
(define-param Rad 1.4
)
(define-param Height 6
)
(define-param shiftZ 0
)
(define Ag
(make dielectric
(epsilon 1)
(polarizations
(make polarizability
(omega 5.3050e-009) (gamma 0.0054)
(delta-epsilon 1.7559e+016)
)
(make polarizability
(omega 0.5668) (gamma 0.2018) (delta-epsilon
2.5607)
)
)
)
)
;eviroment area
(set! filename-prefix false
)
;default material definition
(set! default-material air
)
;geometrical objects
(set! geometry
(list
(make block
(size infinity infinity Height)
(center 0 0 shiftZ)
(material Ag)
)
(make cylinder
(height Height)
(radius Rad)
(center 0 0 shiftZ)
(material air)
)
)
)
(make source
(src (make gaussian-src
(frequency fcen) (fwidth df)))
(amp-func (lambda (p) (exp (* 0+2i pi kx (vector3-x p)))))
(component Hy)
(center 0 0 (- (/ cell_numZ 2) pml_width) )
(size cell_numX (if (= cell_numY no-size) 0 cell_numY) 0))
)
)
(define transAll ; transmitted flux
(add-flux 0.19 0.2 200
(make flux-region
(center 0 0 (+ 2 (- pml_width (/ cell_numZ 2))) )
(size cell_numX cell_numY 0 )
(direction Z)
(weight -1)
)
)
)
(run-sources+ TotalTime
(at-beginning output-epsilon)
;(at-every 2 output-efield-x)
;(stop-when-fields-decayed TotalTime Hy (vector3 0 0 (+ 2 (- pml_width
(/ cell_numZ 2)))) 1e-5)
)
(display-fluxes transAll)
(save-flux "TransAll" transAll)
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