ESPCI

Abstract:

We present experiments carried on flows involving strong capillary effects: liquid curtains, arrays of liquid columns formed when the curtains break, and dewetting of films flowing along inclined surfaces. These flows are important for technical applications (heat exchangers, coating technics) and also address fundamental issues. For instance, the liquid column arrays constitute a model one-dimensional cellular pattern which dynamics has been investigated in great details on a circular overflowing fountain. Different dynamical states are observed: localized oscillations of the column position, drift at constant speed of asymmetrical cells around the fountain perimeter, spatio-temporal intermittency. The data re treated in order to build scaling laws, that are compared with available theories and discussed in physical terms. In experiment, dewetting of flowing films as been investigated on inclined plates of controlled wettability: a well defined universal shape of dry patches is evidenced and theoretically recovered by a simple scaling argument. We also present measurements and theoretical estimates of the critical flow rate above which this shape becomes unstable leaving a fully wetted plane.