• low-order model
• non-linear observer
• filter
• POD

The capabilities of a POD-based flow estimation technique are
investigated at Re=150, Re=300 and Re=22000.
In order to increase the accuracy of the POD modes, two filtering
procedures of the high frequency dynamics
of the velocity fields used to obtain the POD basis are performed.
Both the methods are based on convolution
with a box filter: once in time and once in space. These POD bases
are used within a non-linear observer
estimation technique applied to two- and three-dimensional unsteady
flow past a square cylinder in the cases
reported above.