A simple ILU preconditioning coupled to Orthomin method

Conjugate gradient type methods with preconditionings based on incompleteLU factorization (ILU) are known to be very useful for solving nonsymmetric linear systems of equations. In particular, the effectiveness of such iterative methods has been demonstrated on sparse linear systems which arise from discretizing non-self adjoint elliptic problems. In this paper, we present a simplifiedILU preconditioning coupled to a variational iterative method (Orthomin) on a model problem. It is shown that this simplified version ofILU is easy to implement and when coupled to Orthomin method, is as competitive or better than the standardILU with Orthomin method.