drumhole

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drumhole

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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