Komkov, Vadim (1986) Variational principles of continuum mechanics with engineering applications.
Archimedes' principle | uncertainty principle | Aufbau principle | The Principle of Evil Made Flesh | Bernoulli's principle | An Essay on the Principle of Population | Pauli exclusion principle | Pareto principle | Homestead principle | A Man of Principle | Variational properties | Variational Bayesian methods | variational Bayesian methods | Superposition principle | Scheimpflug principle | Sabatier principle | Principle of indifference | Pontryagin's minimum principle | Peter Principle | Peter principle | Mediocrity principle | Maupertuis' principle | Mach's principle | Le Chatelier's principle | KISS principle | Jacobi's principle | Holographic principle | General Six-Principle Baptists | Fisher's principle | Fermat's principle of least time |
The last four equations describe the evolution of slowly varying wave trains over bathymetry in interaction with the mean flow, and can be derived from a variational principle: Whitham's average Lagrangian method.