Applications of Nambu Mechanics to Systems of Hydrodynamical Type II

In this paper we further investigate some applications of Nambu mechanics in hydro- dynamical systems. Using the Euler equations for a rotating rigid body Nevir and Blender (J. Phys. A 26 (1993), L1189-L1193) had demonstrated the connection be- tween Nambu mechanics and noncanonical Hamiltonian mechanics. Nambu mechanics is extended to incompressible ideal hydrodynamical fields using energy and helicity in three dimensional (enstrophy in two dimensional). In this paper we discuss the Lax representation of systems of Nevir-Blender type. We also formulate the three dimen- sional Euler equations of incompressible fluid in terms of Nambu-Poisson geometry. We discuss their Lax representation. We also briefly discuss the Lax representation of ideal incompressible magnetohydrodynamics equations.