  Confinement effects by rigid boundaries in the dynamics of ideal fluids are
considered from the perspective of long-wave models and their parent Euler
systems, with the focus on the consequences of establishing contacts of
material surfaces with the confining boundaries. When contact happens, we show
that the model evolution can lead to the dependent variables developing
singularities in finite time. The conditions and the nature of these
singularities are illustrated in several cases, progressing from a single layer
homogeneous fluid with a constant pressure free surface and flat bottom, to the
case of a two-fluid system contained between two horizontal rigid plates, and
finally, through numerical simulations, to the full Euler stratified system.
These demonstrate the qualitative and quantitative predictions of the models
within a set of examples chosen to illustrate the theoretical results.
