Abstract
In this work, the modelling of horizontal two-phase flows within the two-fluid Euler–Euler approach is investigated. A modified formulation of the morphology detection functions within the Algebraic Interfacial Area Density (AIAD) model is presented in combination with different models for the drag force acting on a sheared gas–liquid interface. In the case of free surface flows, those closure laws are often based on experimental correlations whose applicability is limited to certain flow regimes. It is investigated here whether the implementation of the modified blending functions in ANSYS CFX avoids this limitation. The influence of the new functions on the prediction of turbulence parameters in free surface flows is also examined quantitatively for the k-ω and k-ε two-equation turbulence models. Transient simulations of the WENKA counter-current stratified two-phase flow experiment were performed for validation. A prediction of the correct flow pattern as observed in the experiment improved dramatically when a turbulence damping term was included in the standard two-equation models. Using the k-ω and a modified k-ε turbulence model with damping terms close to the interface, better agreement with the experimental data was achieved. The morphology detection mechanism of the unified blending functions within the AIAD is seen as an improvement with respect to the detection of sharp interfaces. Satisfactory quantitative agreement is achieved for the modified free surface drag. Furthermore, it is demonstrated that turbulence dampening has to be accounted for in both turbulence models to qualitatively reproduce the mean flow and turbulence quantities from the experiment.
Highlights
The term “two-phase flow” refers to a flow in which two different physical states of a substance or two different substances exist next to each other
The occurrence of such flows in industrial processes, for example, in the wave-like flows in pressurized water reactors, makes their exact prediction and phase distribution by means of computational fluid dynamics (CFD) very relevant for the safety and efficiency of such processes
The objective of the present work was the validation of the new uniform weighting functions in the Algebraic Interfacial Area Density (AIAD) model according to [8] for the modeling of horizontal two-phase flows with phase interfaces in the two-fluid model
Summary
The term “two-phase flow” refers to a flow in which two different physical states of a substance or two different substances exist next to each other. Two-phase flows are common in nature, such as the movement of water droplets in the air or air bubbles in water up to the formation of waves on water surfaces [1]. The occurrence of such flows in industrial processes, for example, in the wave-like flows in pressurized water reactors, makes their exact prediction and phase distribution by means of computational fluid dynamics (CFD) very relevant for the safety and efficiency of such processes. The phases are separated from each other and do not mix The simulation of such flows with phase interfaces is carried out here based on the Fluids 2020, 5, 102; doi:10.3390/fluids5030102 www.mdpi.com/journal/fluids
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
