Fig. 1

In log–log coordinate, plot of the ratio of POD eigenvalues \(\log (\lambda _k(N)/\lambda _1(N))\) for \(N = 400, 600, 800, 1000, 1500\) grid points
In log–log coordinate, plot of the ratio of POD eigenvalues \(\log (\lambda _k(N)/\lambda _1(N))\) for \(N = 400, 600, 800, 1000, 1500\) grid points