Observation of dispersive shock waves, solitons, and their interactions in viscous fluid conduits

Dispersive shock waves (DSWs) and solitons are fundamental structures in dispersive hydrodynamics, but studies have been severely constrained. Here we report on a novel testbed called the conduit system where one fluid is moved through another via a fluid pipe with virtually no mass diffusion. The interfacial dynamics of this pipe are conservative and are modeled by a scalar, nonlinear, dispersive wave equation, similar to those describing a superfluid. Resultantly, the interfacial waves are effectively dissipationless, which enables high fidelity observations of coherent phenomena such as large amplitude DSWs [1]. Experiments involving solitons, wavebreaking leading to DSWs, and their interactions will be presented. ~The results include the refraction and absorption of a soliton by a DSW and the refraction of a DSW by a second DSW, resulting in two-phase behavior. ~Excellent agreement between nonlinear wave averaging, numerics, and laboratory experiments will be presented. The nonlinear wave dynamics observed in this model system have implications for a broad range of other conservative dispersive hydrodynamic systems. Reference: [1] Maiden et al., PRL 116, 174501 (2016).