This submodule defines Kelvin-Helmholtz instabilities in Cartesian geometry.
This equilibrium is a specific case of the flow driven instabilities.
No magnetic fields are considered in this case (pure HD).
This equilibrium is taken from section 13.2, p. 487 (case b) in
Goedbloed, H., Keppens, R., & Poedts, S. (2019). Magnetohydrodynamics of Laboratory
and Astrophysical Plasmas. Cambridge University Press.DOI.