Dispersion induced by the pollution for the wave equation

In this paper we give a computational method to measure the `dispersion' which is directly related to the `pollution effect'. This pollution effect is observed by various researchers when, the Helmholtz equation, is solved for high wave numbers. The main effect of the `pollution' is that the wave number of the solution obtained via a finite element method is different from the wave number of the exact solution and this is what is called `dispersion'. Using Fourier analysis, we present a numerical method to measure the dispersion corresponding to a finite element method.