LIQUID-LIQUID INTERFACIAL INSTABILITY IN THE VICINITY OF THE CRITICAL-POINT OF A BINARY-LIQUID MIXTURE

The system 2-butoxyethanol/water is used to study the dynamics of the instability of the liquid/liquid interface in the vicinity of the lower critical point of the system. The values of the viscosity parameter A and the interfacial parameter B which determine the shape of the interfacial instability are changed by varying temperature at which the experiments are carried out. The change of the shape of the interfacial region is monitored using a CCD-video-camera. The pictures of the liquid/liquid interface are analysed by determining the number of ''viscous fingers'', the width of the mixing zone and the length of the liquid/liquid contour length as function of time. The analysis of the data is based on the work of Tryggvason and Aref (J. Fluid. Mech. 136, 1 - 30 (1983); 154, 287 (1985)).