## nuts...

General discussions about how to formulate a script for FlexPDE.

### nuts...

title 'Wave Guide in Polar Coordinates'

select
autostage=on
stages=4
modes =5
ngrid=5
nodelimit=3000
errlim=staged(0.1, .01, 0.001, 0.0001)
rematrix=on
alias(x) = "X(cm)"
alias(y) = "Y(cm)"

Variables
Hz U
definitions
dr(Hz) = (x/r)*dx(Hz) + (y/r)*dy(Hz) { functional definition of polar derivatives... }
dphi(Hz) = (-y)*dx(Hz) + x*dy(Hz) {... in cartesian coordinates }
wt=(stage)*pi/60
i=sqrt(-1)
Hz01 = 0.50*sin(wt)
Hz02 = 0.50*sin(wt)
source=Hz01+Hz02
scale=staged(1,2,3,4)
a=1/scale

{Source 1 oscillating}
{Source 2 oscillating with small delay}

initial values
Hz=source U=1/(cosh(x-a))^2
equations
Hz: r*dr(r*dr(Hz)) + dphi(dphi(Hz)) + r*r*lambda*Hz +r*r*source =0 {Eigenvalue Problem}
U:div(a*grad(u)) -scale*dy(u) +4 = 0 {burgers equation}
boundaries

Region 1 'outer'
start(-29.5,29.5) value(u)= 1/(cosh(x-a))^2
arc(center=0,0) angle = 360 !nobc(Hz)

Region 2 start(-3.0,0) point natural(Hz) = Hz01+Hz02 value(u) = 1/(cosh(x-a))^2
arc(center = -3.0,0.850) angle =360

Region 3 start(3.0,0) point natural(Hz) = Hz02+Hz01 value(u) = 1/(cosh(x-a))^2
arc(center = 3.0,0.850) angle =360

Region 4 'inner'
start (-12.5,10.0) value(u)= 1/(cosh(x-a))^2 line to (-10.5,10.0) arc(center=0,10) angle= -180 nobc(Hz)
start (12.5,10.0) value(Hz)= Hz02+Hz01 arc(center=0,10) angle= 180 line to close

start (-12.6,8.0) value(Hz) =Hz01+Hz02 line to(-12.6, 24.0) value(Hz)=0 line to(-15.5,24.0) value(Hz)=0 line to(-15.5,8.0) close
start (12.6,8.0) value(Hz) =Hz01+Hz02 line to(12.6, 24.0) value(Hz)=0 line to(15.5,24.0) value(Hz)=0 line to(15.5,8.0) close

Region 5
start(-6.0,4.0) line to(-4.0,4.0) value(Hz) =Hz01+Hz02 line to (3.0,8.0) value(Hz) =Hz01+Hz02 line to (1.0,8.0) close

PLOTS
elevation(Hz) from (-10,10) to (10,10) from (-9,11) to (9,11)
elevation(Hz) from(-10,10) to (10,10) from (-8,12) to (8,12)
elevation(Hz) from( -10,10) to (10,10) ON "outer"
vector(dr(Hz), dphi(Hz))
contour(Hz)
contour(u)
contour(dr(Hz), dphi(Hz))
surface(u)

MONITORS
contour(source) as "Solution"
vector(dr(Hz), dphi(Hz))
end

Why? it was working some moments ago, now it is not. can you fix this oversight?
compxci

Posts: 16
Joined: Tue Oct 25, 2011 7:18 pm

### Re: nuts...

What do you mean by "does not work"?
You will have to give us more information about what the failure you are seeing before we can comment.
This appears to work fine on my machine (professional license on a Windows XP system).
If you are working with a student version, you could simply be reaching the student node limit.
moderator

Posts: 362
Joined: Tue Jan 11, 2011 1:45 pm