Eigen-value Eigenvalues and eigenfunctions 12 Eigenvalue problem 6 Variational principles 6 Variational techniques 6 Arnold's theorem 4 Axisymmetric flow 4 Basic flow 4 Beltrami 4 Beltrami flow 4 Complex topology 4 Eigenvalue problems 4 Enstrophy 4 Euler flows 4 Flow experience 4 Flow structure 4 Force-free magnetic fields 4 Gravity waves 4 Ideal fluids 4 Infinity laplacian 4 Kelvin waves 4 Laplace transforms 4 Laplacians 4 Magnetic fields 4 Magnetohydrodynamics 4 Stability 4 Topology 4 A posteriori error estimators 2 A-posteriori error estimates 2 Adaptive procedure 2