Is there an alternative method for TDMA (Thomas algorithm)
I'm using TDMA to solve for the SIMPLE algorithm. For small grid, the TDMA converged quite fast but for large grid the convergence rate is killing me. Is there an alternative to TDMA that is simple to code and give faster convergence apart from Gauss elimination (consume alot of memory)?

Try an iterative solver  check lapack library for example, you can find some hints about what solver you can use for a linear system in the book of Peric.
BTW TDMA is just a specialized Gauss elimination for tridiagonal system. Do 
Thanks alot..really appreciate your response..

I am slightly puzzled by the use of the term "convergence"... The Thomas algorithm is a direct solver (i.e not iterative), as pointed out.
I think that the Thomas algorithm is part of an algorithm that itself takes a while to converge (ADI, underrelaxation, treatment of nonorthogonal terms, other). You may want to have a check of the algorithm as well. Hope this help. Julien 
Krylov with Schurcomplement preconditioning
Classical SIMPLE is really not a very robust algorithm, a much better approach is to discretize implicitly in time and solve the linear systems with a Krylov method (like GMRES) preconditioned with a Schurcomplement scheme. For example,
Code:
@article{elman2008tcp, 
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