Variational Derivation of the Geophysical Green-Naghdi Shallow-water System
摘要
Under the shallow-water regime and without assuming wave amplitude smallness, we apply the variational approach in the Lagrangian formalism to derive the geophysical Green-Naghdi system. In contrast to the prior derivation in (Fan et al., J. Nonlinear Sci., 32(21), 30 (2022)) that imposed a columnar-flow Ansatz, our method adopts the irrotational-flow assumption (which Fan et al., J. Nonlinear Sci., 32(21), 30 (2022) does not), thereby generating the depth-independent horizontal velocity at leading order.