INTERFACIAL FILM DYNAMICS OF A MOVING MENISCUS INSIDE SQUARE CAPILLARIES: AN EXPERIMENTAL INVESTIGATION

摘要

Mini/micro systems with single- as well as multiphase flows have many appealing pragmatic applications like pulsating heat pipes (PHP), microfluidics, fuel cells, etc. Understanding the inter-facial film dynamics of such systems will help us in manipulating the performance parameters, such as bubble/slug velocity, length, shape, dynamic contact angle, thickness of the liquid film that surrounds the bubbles, mixing and flow circulation within the liquid slugs, and pressure drop along the flow, which will further improve the efficiency of multiphase microsystems. The present work aims at studying the interfacial contact line behavior of a single meniscus and liquid slug formed between different fluids. The experiments were performed using a high-speed camera to determine the dynamic contact angle of a moving meniscus. A single-syringe infusion pump along with a syringe is used, pushed with different speeds to get different flow rates. The interface was viewed and captured through a high-speed camera for four different fluids, viz., water, ethanol, glycerine, and silicone oil. Beside the dynamic contact angle information, present experimental observations were compared with the existing molecular and phenomenological models.