An adaptive selective frequency damping method

The selective frequency damping (SFD) method is an alternative to classical Newton’s method to obtain unstable steady-state solutions of dynamical systems. However, this method has two main limitations: it does not converge for arbitrary control parameters, and when it does converge, the time necessary to reach a steady-state solution may be very long. In this paper, we present an adaptive algorithm to address these two issues. We show that by evaluating the dominant eigenvalue of a “partially converged” steady flow, we can select a control coefficient and a filter width that ensure an optimum convergence of the SFD method. We apply this adaptive method to several classical test cases of computational fluid dynamics and we show that a steady-state solution can be obtained with a very limited (or without any) a priori knowledge of the flow stability properties.