(5)New turbulence modeling for air/water stratified flow
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M. Ghafari∗, M.B. Ghofrani
Department of Energy Engineering, Sharif University of Technology, Azadi Ave., Tehran, Iran
Received 22 April 2019; received in revised form 30 June 2019; accepted 14 August 2019
Available online 2 September 2019
Abstract
The prediction of interfacial turbulence characteristics is one of the still challenging of two-phase stratified flow. The evaluation of some
important parameters such as interfacial heat transfer coefficient based on turbulence kinetic energy and turbulence dissipation rate in some
models, intensifies the importance of turbulence flow correct simulation. High gradient of velocity and turbulence kinetic energy at the
interface of two-phase stratified flow leads to a major overestimation or underestimation of flow characteristics without any special treatment.
Consideration of a source function of turbulence eddy frequency at the interface is one of the common solution employed in past researches.
Although this solution remedies some shortcomings of traditional methods in smooth stratified flow, its application in wavy stratified flow
needs the other modifications. The examination of turbulence characteristics near the free surface reveals that, in addition to turbulence eddy
frequency, the other source function of turbulence kinetic energy should be considered near the free interface. So, a new source function of
turbulence kinetic energy is proposed at the interface based on flow condition. This new method has been employed for Fabre et al. (1987)
experiment designed for air/water stratified flow. The results of simulation have a good agreement with experimental data and turbulence
characteristic can be captured near the free surface.
© 2019 Shanghai Jiaotong University. Published by Elsevier B.V
This is an open access article under the CC BY-NC-ND license.(http://creativecommons.org/licenses/by-nc-nd/4.0/)
Keywords: Stratified flow; Turbulence model; Turbulence kinetic energy; Source function.