Imperial College London

Professor Omar K. Matar

Faculty of EngineeringDepartment of Chemical Engineering

Vice-Dean (Education), Faculty of Engineering



+44 (0)20 7594 9618o.matar Website




Miss Nazma Mojid +44 (0)20 7594 3918




506ACE ExtensionSouth Kensington Campus






BibTex format

author = {Morgan, RG and Ibarra, R and Zadrazil, I and Matar, OK and Hewitt, GF and Markides, CN and Morgan, R and Ibarra, R and Zadrazil, I and Matar, O and Hewitt, G and Markides, C},
doi = {10.1016/j.ijmultiphaseflow.2016.07.009},
journal = {International Journal of Multiphase Flow},
pages = {123--135},
title = {On the role of buoyancy-driven instabilities in horizontal liquid–liquid flow},
url = {},
volume = {89},
year = {2016}

RIS format (EndNote, RefMan)

AB - Horizontal flows of two initially stratified immiscible liquids with matched refractive indices, namely an aliphatic hydrocarbon oil (Exxsol D80) and an aqueous-glycerol solution, are investigated by combining two laser-based optical-diagnostic measurement techniques. Specifically, high-speed Planar Laser-Induced Fluorescence (PLIF) is used to provide spatiotemporally resolved phase information, while high-speed Particle Image and Tracking Velocimetry (PIV/PVT) are used to provide information on the velocity field in both phases. The two techniques are applied simultaneously in a vertical plane through the centreline of the investigated pipe flow, illuminated by a single laser-sheet in a time-resolved manner (at a frequency of 1–2 kHz depending on the flow condition). Optical distortions due to the curvature of the (transparent) circular tube test-section are corrected with the use of a graticule (target). The test section where the optical-diagnostic methods are applied is located 244 pipe-diameters downstream of the inlet section, in order to ensure a significant development length. The experimental campaign is explicitly designed to study the long-length development of immiscible liquid–liquid flows by introducing the heavier (aqueous) phase at the top of the channel and above the lighter (oil) phase that is introduced at the bottom, which corresponds to an unstably-stratified “inverted” inlet orientation in the opposite orientation to that in which the phases would naturally separate. The main focus is to evaluate the role of the subsequent interfacial instabilities on the resulting long-length flow patterns and characteristics, also by direct comparison to an existing liquid–liquid flow dataset generated in previous work, downstream of a “normal” inlet orientation in which the oil phase was introduced over the aqueous phase in a conventional stably-stratified inlet orientation. To the best knowledge of the authors this
AU - Morgan,RG
AU - Ibarra,R
AU - Zadrazil,I
AU - Matar,OK
AU - Hewitt,GF
AU - Markides,CN
AU - Morgan,R
AU - Ibarra,R
AU - Zadrazil,I
AU - Matar,O
AU - Hewitt,G
AU - Markides,C
DO - 10.1016/j.ijmultiphaseflow.2016.07.009
EP - 135
PY - 2016///
SN - 0301-9322
SP - 123
TI - On the role of buoyancy-driven instabilities in horizontal liquid–liquid flow
T2 - International Journal of Multiphase Flow
UR -
UR -
VL - 89
ER -