Unstable snoidal waves

The present paper deals with results of orbital instability for a class of evolution equations which possess snoidal waves as solution. The periodic solutions obtained from our study tend to the classical kink wave solutions in the infinite wavelength scenario. The instability approach is based on the classical Grillakis, Shatah and Strauss’ theory and the new development obtained by Angulo and Natali, which establishes orbital instability results for a class of Korteweg–de Vries‐type equations.