Seiches: a tale of misconceptions?
(2024) , 34 pages
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- Abstract
- The governing equations of a non-dissipative, two-layer hydrodynamic model are linearised. Following classical textbooks, the equations of the external mode and that of the internal one are established. Then, the related inertia gravity waves are briefly studied. Next, in an idealised, one-dimensional lake, external and internal seiches (i.e., free oscillations) are modelled, underscoring the fact that the timescale of the external mode is much smaller than that of the internal one. Under simple initial conditions, the surface and thermocline displacements are seen to be continuous piecewise linear functions in space exhibiting oscillations in time, which are best understood in the framework of the theory of distributions. On the other hand, the response to an abruptly imposed wind forcing leads to solutions of the same nature, which might not be fully in accordance with common knowledge about seiching motions. Volume and mechanical energy conservation are dealt with in Appendix A. We also briefly investigate the impact of vertical discretisation on the propagation of hydrostatic internal waves in level models (Appendix B).
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Deleersnijder, E. (2024). Seiches: a tale of misconceptions? https://hdl.handle.net/2078.5/243844