[petsc-users] floating region help

[Gong Ding]

Hi,
I am testing the floating region problem.
The model problem can be described as a 1D poisson equation.
The potential of left end is fixed as 1V, the right end is fixed as 2V.
In the left/right part, the conductance is low, i.e. 1
In the middle part, the conductance is much higher, i.e. 1e6
*-1-*-1-*-1-*-1-*-1-*-1e6-*-1e6-*-1e6-*-1-*-1-*-1-*-1-*
As a result, the potential in the middle region is weakly controled by the left and right endpoint.
Since the conductance of left part and right part is low, the middle region is floating.
Is it possible to use null space method here?
I guess the null space is the vector that the location of corresponding point in the floating region is 1.0, otherwise 0.0.
And here we solve Ax=b with null vector n.
The solution xn has no component parallel to n.
Assuming the real solution should be xn+a*n,
Then A(xn+a*n)=b, and a can be solved from a*n = b-Axn.
 
Am I right? Or there are some better method to process the floating region?
 
Gong Ding
 
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