MARANGONI CONVECTION  : A SIMPLE DEMONSTRATION OF EVAPORATIVELY DRIVEN CONVECTION.  SHOWS PLANFORMS, CRITICALITY AND CELL SELECTION SIZE.

Typical equipment.  Do not use the all glass cylindrical dish shown here.  Instead use the fabricated cylindrical container with plexiglass sides and a metal base.  

1. Fill to a few mm depth with Ethyl Alcohol laced with aluminum flakes.  
2. Convection occurs immediately.
3. Save fluid afterwards

Typical view looking down into the dish.  Longitudinal cells form near the rim because of a big roll cell that is forced by thermal effects near the sidewall.  This roll shears the high wavenumber convection cells into little rolls that point inwards.  Over the bulk of the container polygonal cells form.  Wavelength depends on depth.  Tilt the tank slightly to visualize this.

QT MOVIES:

1. CONVECTION IN A 1CM DEEP LAYER      (BIG SCREEN)
2. CONVECTION NEAR THE EDGE OF THE CONTAINER   (BIG SCREEN)
3. CONVECTION ON A ROTATING TABLE - 2 SEC PERIOD.    (BIG SCREEN)