Flow instability of glycerol/water/triton-X-100 thin liquid film system

摘要

The flow stability of Glycerol/water/Triton-X-100 nonionic surfactant of single layer liquid film flowing down an in-clined plane was systematically studied in this work. Capillary wave at the liquid surface was measured by capillary wave/laser detection methd. Specifically, we examined the effect of Triton-X-100 surfactant on the damping of capillary waves on the free surface of glycerol/water liquid film. The stability of apillary wave disturbances on the liqiuid surface was characterized by measuring the wave damping coefficient #beta# . The stability and instability boundary is identified by the condition #beta# chemical bounds 0. The corresponding value of the wave number at the #beta# chemical bounds 0 condition is referred to as the critical wave number, a #alpha# _c chemical bounds 2 #pi# h/ #lambda# , where h is the film thickness. This critical parameter, #alpha# _c, is used to characterize the flow's stability, and determined as a function of Reynolds Number, Elasticity Number and Weber Number. We found that the flow stability increase with the surfactant concentration. At high concentrated solutions (above the CMC), it was found that, for a fixed Reynolds Number, #alpha# _c is independent of surfactant concentration and the Weber Number. A comparison of the effects of surfactant elasticity and sruface tension to flow stability is discussed.