Galilei group with multiple central extension, vorticity, and entropy generation: Exotic fluid in 3+1 dimensions
Physical Review D
A noncommutative extension of an ideal (Hamiltonian) fluid model in 3+1 dimensions is proposed. The model enjoys several interesting features: it allows a multiparameter central extension in Galilean boost algebra (which is significant being contrary to the existing belief that a similar feature can appear only in 2+1-dimensions); noncommutativity generates vorticity in a canonically irrotational fluid; it induces a nonbarotropic pressure leading to a nonisentropic system. (Barotropic fluids are entropy preserving as the pressure depends only on the matter density.) Our fluid model is termed "exotic" since it has a close resemblance with the extensively studied planar (2+1 dimensions) exotic models and exotic (noncommutative) field theories.
Das, Praloy and Ghosh, Subir, "Galilei group with multiple central extension, vorticity, and entropy generation: Exotic fluid in 3+1 dimensions" (2017). Journal Articles. 2305.