Experiments are conducted to study the solidification from below
ammonium chloride. Thermochromic liquid crystal paints are used to visualize
temperature field simultaneously in both the liquid and the mushy layers.
quasi-two-dimensional cell (thickness 10 mm), mushy-layer and boundary-layer
are revealed as bumps in isotherms within and above the mushy layer, respectively.
The onset, growth and decay of these convective modes are measured by monitoring
the progression of the bumps during an experiment. The small-wavelength
mode is short-lived (approximately 20–30 min), whereas the larger-wavelength
mushy-layer mode survives for several hours, dominating the flow even long
the growth has stopped. Experiments in a Hele-Shaw cell (thickness 2.0
simultaneous visualization of both the temperature field and the solid
coarsening mechanism is observed in which the flow spontaneously changes,
the strength of plume convection in one of the channels, and leading to
dendrites into the channel. An oscillatory convective mode is also observed,
an indication of one of the oscillatory modes recently predicted by Chen,
Lu & Yang
(1994) and by Anderson & Worster (1995).