On the Hamiltonian formulation of incompressible ideal fluids and   magnetohydrodynamics via Dirac's theory of constraints
  The Hamiltonian structures of the incompressible ideal fluid, including entropy advection, and magnetohydrodynamics are investigated by making use of Dirac's theory of constrained Hamiltonian systems. A Dirac bracket for these systems is constructed by assuming a primary constraint of constant density. The resulting bracket is seen to naturally project onto solenoidal velocity fields. 
Cristel Chandre (CPT), Philip J. Morrison (IFS), Emanuele Tassi (CPT)
physics.plasm-ph nlin.CD physics.flu-dyn