Faraday instability in a linear viscoelastic fluid

The onset of surface waves in a vibrated layer of a viscoelastic fluid is investigated theoretically. For vibration frequencies close to the inverse relaxation time of the non-Newtonian fluid, surface waves respond harmonically instead of being subharmonic as is usually the case in Newtonian fluids. This prediction has been made on the basis of the Maxwell model for viscoelastic fluids, but the result is robust and has been confirmed by using the empiric viscosity spectrum for a mixture of 2% polyisobutylene in primol. The parameter range is determined, where harmonic surface waves are favored.