As a liquid bath is perturbed, at a particular acceleration a standing wave, called Faraday waves, will appear on the whole surface of the bath. Regular square patterns are observed for single-frequency forcing and the wavelength depends on the liquid properties and exciting frequency. The regular pattern becomes more complex by adding a second frequency component into the forcing signal. A slight presence of the second frequency does not affect the instability as triggered by the first. However when both acceleration are large, the more complex quasi patterns are produced. (Liquid bath: Silicone oil 20 Cst, light with pink and white diffuse, Nikon camera with macro lens.)
Induced Faraday instability by two-frequency forcing —Naresh Sampara, University of Nottingham

As a liquid bath is perturbed, at a particular acceleration a standing wave, called Faraday waves, will appear on the whole surface of the bath. Regular square patterns are observed for single-frequency forcing and the wavelength depends on the liquid properties and exciting frequency. The regular pattern becomes more complex by adding a second frequency component into the forcing signal. A slight presence of the second frequency does not affect the instability as triggered by the first. However when both acceleration are large, the more complex quasi patterns are produced. (Liquid bath: Silicone oil 20 Cst, light with pink and white diffuse, Nikon camera with macro lens.)

https://fluids.ac.uk/files/06_Naresh_Sampara_Farday_v2_1024w.1543871153.png