Measurement of Thrusts and Estimation of Elastic Stresses of Liquids Passing Through Micro-Orifices

Abstract

Jet thrusts of several kinds of liquids issuing through small orifices were measured and compared with the predictions from numerical simulations of the Navier-Stokes equations. Reasonable agreements for so-called Newtonian fluids were obtained between the experimental and predicted thrusts for capillaries and orifices with openings of the order of 100 μm size, but the experimental thrusts were found to be below the predictions for orifices of the order of 10 μm. It was suggested that water and glycerol solutions have an elastic property for elongational flows passing through small orifices. As to surfactant aqueous solutions, cationic surfactant(BC) and non-ionic surfactant(AE (23)) provided thrusts lower than those of water, but anionic surfactant(LAS) showed almost the same thrusts as water. Also, lower thrusts were measured for dilute polymer aqueous solutions of PEO(18). A mean elastic stress for the tested liquids was evaluated by using the measured thrusts, and discussion was made on the idea that flows near the wall are affected by an interaction between anions on the surface of orifice and charged molecules of surfactants.

Flow Properties of Several Types of Liquid Flows through Micro-Orifices

“…This development of viscoelastic properties by certain surfactants agrees qualitatively with the results presented in Section 4 (Figs 5(a)~(e) and 6(a)~(e)). Therefore, it is considered that the decrease in both jet thrust and pressure in these experiments is caused by elastic stress, ES, which is expressed using either (3) or (4) (15), (32) .…”