Numerical effects on the prediction of flow instabilities in channels with sudden-expansions

We have considered the problem of flow through a suddenly-expanded channel and performed a computational investigation to examine numerical effects on the prediction of flow instability and bifurcation phenomena. The results revealed that the solution of the flow depends on the numerical method employed. We have employed Godunov-type methods in conjunction with first-, second- and third-order accurate interpolation schemes. It is shown that the order of accuracy of the interpolation used in the discretisation of the wave-speed dependent term and averaged part of the intercell flux affects the prediction of the instability. Computations using first-order discretisation for the calculation of the flux components results in symmetric stable flow, whereas second- and third-order discretisations lead to a symmetry-breaking bifurcation.