Spatiotemporal Dynamic of Two-dimensional core annular flow in square channel

Abstract

In this work, we study the spatiotemporal dynamics of a two-dimensional core-annular flow (CAF) in a square channel of an oil/water system. The flow rate of oil is fixed at Qo=0.19 l/s and the flow rate of water Qw is varied from 0.20 l/s to 0.46 l/s. For large values of Qw (typically Qw>0.23l/s), the CAF is unstable, and it becomes stable for low values of Qw (typically Qw<0.23l/s). The spatiotemporal diagram technique is used to determine the characteristics of the water-oil interface, namely the entry length, height, parallel length, frequency, wavenumber, phase velocity, amplitude and spatial growth rate of wave amplitudeas function of the water flow rate Qw. Theses characteristics are used to explain the pressure drop as function of the water flow rate.