Exact Solutions of a Fully Nonlinear Two-Fluid Model
  A nonlinear coupled Choi-Camassa model describing one-dimensional incompressible motion of two non-mixing fluid layers in a horizontal channel has been derived in Ref.1. An equivalence transformation is presented, leading to a special dimensionless form of the system, with the number of constant physical parameters reduced from five to one. A first-order dimensionless ordinary differential equation describing traveling wave solutions is analyzed. Several multi-parameter families of exact closed-form solutions of the Choi-Camassa model are obtained, describing periodic, solitary, and kink-type bidirectional traveling waves. 
Alexei F. Cheviakov
physics.flu-dyn