3 research outputs found
Planform selection in two-layer Benard-Marangoni convection
Benard-Marangoni convection in a system of two superimposed liquids is
investigated theoretically. Extending previous studies the complete
hydrodynamics of both layers is treated and buoyancy is consistently taken into
account. The planform selection problem between rolls, squares and hexagons is
investigated by explicitly calculating the coefficients of an appropriate
amplitude equation from the parameters of the fluids. The results are compared
with recent experiments on two-layer systems in which squares at onset have
been reported.Comment: 17 pages, 7 figures, oscillatory instability included, typos
corrected, references adde
Oscillatory granular segregation in a long drum mixer
Heterogeneous granular mixtures tend to segregate when tumbled in
a partially filled, horizontal rotating drum. The dynamical
evolution of segregation can, under certain conditions, be
oscillatory. Continuum, order parameter-style models of this
process posit two coupled fields which oscillate out of phase
with one another. Here we examine three candidate fields, the
surface concentration, the local streaming angle and the
projected concentration of the subsurface core. We find that all
these quantities are in phase with one another, in contradiction
to a recent order parameter model