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{ THENEQ.PDE

 

   This example demonstrates the use of sequenced equations in a steady-state problem.

   The equations are not coupled, and are solved individually.

 

}  

title 'Sequenced Equations'  

 

select  

  errlim=1e-5  

  ngrid=50  

 

Variables  

  u,v,w  

 

definitions  

  k1 = 1  

  k2 = 2  

  k3 = 3  

  u0 = 1-x^2-y^2  

  v0 = 2-x^2-y^2  

  w0 = 3-x^2-y^2  

  sourceu = 4*k1  

  sourcev = 4*k2  

  sourcew = 4*k3  

 

equations  

  u:     div(K1*grad(u)) +sourceu = 0  

then  

  v:     div(K2*grad(v)) +sourcev = 0  

then  

  w:     div(K3*grad(w)) +sourcew = 0  

 

boundaries  

  Region 1  

    start(-1,-1)  

    value(u)=u0         value(v)=v0         value(w)=w0  

    line to (1,-1) to (1,1) to  (-1,1) to close  

 

  plots  

    surface(u)  paint as "First"

    surface(v)  paint as "Second"

    surface(w)  paint as "Third"

    elevation(u,v,w,su,sv,sw) from (-1,0) to (1,0)  

end