Oscillatory hydrodynamic flow due to concentration dependence of surface tension

Using a two species reaction-diffusion model in the excitable regime coupled to the hydrodynamic equations we discuss how a group of chemical waves drives an oscillatory convective motion in a fluid layer The experiments show an oscillatory behavior of the surface flow with the maximum velocity opposite to the direction of wave propagation. The mechanism considered is a variation of the surface tension along a free surface due to an inhomogeneous concentration distribution. Our results lead to an understanding of the observed oscillatory flow as well as of the large scale features observed.