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Momentum and pseudomomentum in a shallow water equation:
https://arxiv.org/abs/2208.05657 J. A. Hanna
A basic shallow water system with variable topography is analyzed from the point of view of a Lagrangian derivation of momentum, energy, and pseudomomentum balances. A two-dimensional action and associated momentum equation are derived. The latter is further manipulated to derive additional equations for energy and pseudomomentum. This revealed structure emphasizes broken symmetries in space and a reference configuration, and preserved symmetry in time.
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Subjects: Fluid Dynamics (physics.flu-dyn); Mathematical Physics (math-ph); Classical Physics (physics.class-ph)