Rayleigh Taylor instability
A case with strong interface deformation is investigated. It
is described by the unstable situation of a heavy fluid resting upon a
lighter one in a gravitational field. The density ratio of the fluids is
0.1383 and their viscosities are equal. This case is two-dimensional and
no surface tension acts on the interface.
A rectangular domain of
dimensions 1x4 was used. The interface is initialized with a sinusoidal
perturbation of amplitude A=0.05. Symmetry boundary conditions were used
on all domain boundaries. The non-dimensional numbers are Re = 391.37
and Fr = 0.31928. The same conditions were simulated by Lopez et al.
(2005) using an interface capturing method and by Popinet and Zaleski
(1999) using a front tracking algorithm. The present results for the
shape of the interface are displayed in fig. (3). The instability
develops a typical mushroom shape. At larger times, thin filaments are
generated which are clearly resolved by the mesh.