The proper orthogonal decomposition (POD) method for the instationary Navier-Stokes equations is considered. Several numerical approaches to evaluating the POD eigenfunctions are presented. The POD eigenfunctions are applied as a basis for a Galerkin projection of the instationary Navier-Stokes equations. And a low-dimensional ordinary differential models for fluid flows governed by the instationary Navier-Stokes equations are constructed. The numerical examples show that the method is feasible and efficient for optimal control of fluids.
Two inequalities in the book Navier-Stokes Equations Theory and Numerical Analysis written by Roger Temam are improved via Schwarz’s inequality and Young’s inequality, and the coefficients of them are simplified from 21/4·31/2 and 21/2·33/4to 21/4 and 23/4, respectively. Therefore, to some extent the approximating error can be reduced and the accuracy of approximation can be improved.
