The decay of grid turbulence in polymer and surfactant solutions

The decay of turbulence behind a towed grid is studied in polymer and surfa ctant solutions with the use of particle image velocimetry. Unlike in water , the turbulent energy components show marked anisotropy, and decay more sl owly. These differences are stronger for initial periods of time, but persi st through the entire period of decay. The major difference between the pol ymer and surfactant solutions is that the small scales are more strongly da mped in the former. (C) 1999 American Institute of Physics. [S1070-6631(99) 04108-2].