Is the electromagnetic field in a medium a fluid or a wave?

The electromagnetic field is found to travel inside a medium as a fluid that experiences a magnetic force on moving charges it encounters, and a drag (viscous) force. The field equations governing the dynamics of the fluid are found to be some altered Maxwell's equations. The energy conservation equation reveals that the energy flows is dissipationless, and lies in the plane containing the electric and magnetic fields only and no transverse flow. It is also conserved under the duality transformation. The magnetic field component along the velocity (v→) direction is conserved, while the electric field component is not. The electromagnetic field induces magnetization and polarization densities in the medium that are given by M→=ɛv→×E→ and P→=ɛv→×B→, respectively, where ɛ is the medium permittivity, and E→ and B→ are the electric and magnetic fields. The electromagnetic field induces a local electric field that is equal and opposite to that one arised from a static cylindrical charge distribution.