Int. J. Multiphase Flow Vol. 10, No. 3, pp. 371-383, 1984 0301-9322/84 $3.00 + .00 Printed in Great Britain. Pergamon/Ehevier AN INVESTIGATION INTO THE INTERFACIAL SHEAR STRESS CONTRIBUTION IN TWO-PHASE STRATIFIED FLOW A. J. JOHNSTON Department of Civil and Mining Engineering, University of WoUongong, New South Wales, Australia 2500 (Received 5 May 1983; m revised form 1 September 1983) Abstract--This paper provides a combined theoretical and experimental investigation into the contribution of interfacial shear stress in certain co and counter-current flows in circular pipes. Based on momentum balance two equations were developed for such flows then two fluid systems of significantly different density ratio were experimentally tested to quantify these equations. 1. INTRODUCTION Most of the material which has been published on stratified two phase flow has concentrated on situations where the gas and liquid phases are in the same direction (i.e. co-current) where the velocity of the gas is considerably greater than the liquid. Such situations are manifested in certain boiler pipes, refrigerator tubes and natural gas pipelines. In contrast to this the amount of published material on co-current flow where the velocities of the gas and liquid phases are similar in magnitude and, on counter-current flow where the liquid and gas phases travel in different directions, has been relatively small. A practical example where such counter-current flow situations are possible is in the inlet bottles (or pipes) of a parallel bottle slugeatcher which is an installation often located at the terminal of a two phase natural gas pipeline. Its principal function is to separate the liquid and gas phases and in doing so, counter-current flow is facilitated in the inlet bottles. The flow characteristics in these bottles are closely related to the capacity and controlled operation of the slugcatcher. Hence, to improve the general understanding of these stratified two ,phase flows a combined theoretical and experimental investigation was completed. 2. THEORETICAL ANALYSIS Considering the smooth stratified co-current flow condition illustrated in figure 1, the following momentum balance equations for each phase can be written; liquid phase, AL " de + "[oL " S L " dx - z~ " Si " dx - PL " A L " d x • g • sin ,t = 0 [1] gas phase, AG " dp + %re'S a" dx + xi " S~ " dx - p~ " A~ " dx " g • sin,t= 0 [2] y sL Figure 1. Stratified co-current flow. 371