How is the sys of linear eqns solved using PETSc in this application?

[Ben Tay]

Hi,

I'm formulating a NS solver which computes the flow past an airfoil. The
airfoil has a c-grid and it overlaps with the background cartesian grid. In
other words, it is a chimera or overset grid application.

The boundary cells of the c-grid are connected to the cartesian grid thru
interpolation stencil. One way to solve the problem is to solved implicitly
ie for each cell
phi(c-grid)=a1*phi(cart,1)+a2*phi(cart,2)+a3*phi(cart,3)+a4*phi(cart,4) and
vice versa for the phi(cart). This is entered into the sys of linear eqns
comprising of c-grid and cartesian and solved all at once.

Another way is to solve the cartesian grid eqns fully 1st, compute
phi(c-grid) using the known phi(cart,*) and solve the c-grid fully ie
explicit solving.

Is it possible to do this in PETSc:

1. Do 1 iteration of cartesian grid eqns
2. compute phi(c-grid) using the newly iterated phi(cart,*) values
3. Do 1 iteration of c-grid eqns
4. compute phi(cart) using the newly iterated phi(c-grid,*) values
5. go back to 1.

Or is this mtd the same as solving the whole sys implicitly (ie 1st case)?

Thanks
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