Fluttering flag

A fluttering flag is a model for studying a dynamic aeroelastic instability known as flutter, in a low speed fluid flow. Flutter also generates drag on the flexible flag. So, first, one would like to know at a given Reynolds number, at what flow speed would a flag of a given mass ratio, flutter. Also, one would like to know the relation between the kinematics of the flag and the cirulatory and non-circulatory fluid forces on the flag.

Incompressible DNS simulations of a fluttering flag for a mass ratio of  1 and a non-dimensional flutter speed of 18.1 at a Reynolds number of 1000.

Unsteady incompressible vortex panel simulations of a fluttering flag for a mass ratio of  1 and a non-dimensional flutter speed of 7.

Amplitude envelope of the foil fluttering. On the left the mass ratio is 0.2 and is based on the unsteady vortex panel simulations, and on the right for a mass ratio of  0.1 and is based on DNS simulations at a Reynolds number of 1000.