Comment on "Directed motion of spheres by unbiased driving forces in viscous fluids beyond the Stokes' law regime"

Pedro J. Martínez, Ricardo Chacón

In a recent paper by Casado-Pascual [Phys. Rev. E \textbf{97}, 032219 (2018)], directed motion of a sphere immersed in a viscous fluid and subjected to zero-average biharmonic forc…