LINEAR-STABILITY OF A TRI-LAYER FLUID SYSTEM DRIVEN BY THE THERMOCAPILLARY EFFECT

The onset of Marangoni instability in a tri-layer fluid system heated across its interfaces is studied. Both oscillatory and stationary inst abilities to disturbances of a finite wavenumber are found. Their comp etition often leads to the emergence of codimension two-points and to the discontinuity of a critical wavenumber. The flow field at the crit ical threshold usually consists of three convective cells across the s ystem, each in its own layer. However, the flow field in the middle la yer can sometimes itself be subdivided into two superimposed convectiv e cells. (C) 1997 Published by Elsevier Science Ltd.