Observations of highly localized oscillons with multiple crests and troughs.

Two types of stable, highly localized Faraday resonant standing waves with multiple crests and troughs are observed in an ethanol-water solution partly filled in a Hele-Shaw cell vertically oscillated with a single frequency. Systematical experiments are performed to investigate the properties of these oscillons. It is found that the wave height of these oscillons is independent of fluid depth from 1 to 5 cm. In particular, some experiments are performed to indicate the high localization of the oscillons, which suggests that these oscillons may be regarded as a combination of the two elementary oscillons discovered by Rajchenbach et al. [Phys. Rev. Lett. 107, 024502 (2011)], for instance, (2,3)=(1,1)+(1,2), where (m,n) denotes an oscillon with m crests and n troughs. So, our experiments also reveal an elegant "arithmetic" of these oscillons. These experimental phenomena are helpful to deepen and enrich our understanding about Faraday waves.