Elastohydrodynamics of Faraday waves

The natural frequency of a fluid layer overlying on a rigid wall depends on the density of the fluid, surface tension at the free surface and the waveform that evolves at the free surface. However, the presence of a soft-gel layer underneath the fluid layer is expected to alter the natural frequency of the fluid layer. In this work, a linear stability analysis is carried out to show that the natural frequency of the fluid layer is altered by the elasticity of the compliant soft-gel layer. As a consequence of a shift in the natural frequency, linear stability calculations shown that there is also a shift in the instability regions when the fluid layer lying on the soft-gel is subjected to parametric forcing. This indicates that the soft-gel layer can either aid in the formation of Faraday waves or can also suppress the formation of these waves at the free surface of the fluid. This behaviour is also seen in the Faraday threshold calculations, where the presence of a deformable soft-gel layer either raises or lowers the threshold to induce an instability.