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{ DRUMHOLE.PDE
*******************************************************************
This example is a modification of DRUMHEAD.PDE, in which
the vibrating membrane has a circular hole.
*******************************************************************
}
title "Vibrational modes of a drumhead with a hole"
select
modes=8 { Define the number of vibrational modes desired.
The appearance of this selector tells FlexPDE
to perform an eigenvalue calculation }
Definitions
enohole = ARRAY(5.783186, 14.68197, 14.68197, 26.37459, 26.37459, 30.471262, 40.70644, 40.70644)
variables
u
equations { the eigenvalue equation }
U: div(grad(u)) + lambda*u = 0
boundaries
Region 1
start(0,-1)
value(u) = 0
arc(center=0,0) angle 360
start(0,-0.4)
natural(u)=0
arc(center=0,-0.2) angle=360
monitors { repeated for all modes }
contour(u)
plots { repeated for all modes }
contour(u)
surface(u)
transfer(lambda,u) file="ur"
summary
report(lambda) report(enohole[mode]) as " No Hole"
end