Structure of surface deformation waves induced in spiral pattern in the Belousov-Zhabotinsky reaction

A surface deformation wave coupled with an oscillatory hydrodynamic flow is observed in a thin solution layer of the Belousov-Zhabotinsky reaction. The observation is carried out with a Mach-Zehnder interferometric system under the excitation of chemical spiral waves in the solution. The surface deformation wave is induced spontaneously at the end of a dish. It propagates towards the center of the spiral waves, and disappears there. This fact leads to understand the oscillatory flow as a propagating convection waves having long-scale surface deformation. The Marangoni effect or surface tension driven convection with deformable surface plays an important role to establish the oscillatory flow.