Prediction of Horizontal Gas–Liquid Segregated Flow Regimes with an All Flow Regime Multifluid Model

Abstract

The generalized multifluid modelling approach (GEMMA) has been developed to handle the multiplicity of flow regimes and the coexistence of interfaces of largely different scales in multiphase flows. The solver, based on the OpenFOAM reactingEulerFoam family of solvers, adds interface resolving-like capabilities to the multifluid solver in the cells occupied by large interfaces. In this paper, GEMMA is further developed to predict stratified and slug flow regimes in horizontal ducts. The suppression of the turbulence and the wall-like behaviour of large interfaces is modelled with an additional dissipation source. This enables an accurate prediction of the velocity and of the turbulence kinetic energy in a stratified channel flow and the capturing of the formation and the travel of liquid slugs in an annulus. Large interfaces are identified and tracked, not only in the smooth and wavy stratified regimes but also in the much more perturbed interfaces of liquid slugs. The present work confirms GEMMA to be a reliable approach to provide all flow regime modelling capabilities. Further development will be focused on large interface momentum-transfer modelling, responsible for the overestimation of the interfacial shear and the limited liquid excursion during slugs, and the extension to interface break-up and the entrainment of bubbles and droplets, to handle the entire range of regimes encountered in horizontal flows.

Momentum exchange modeling for coarsely resolved interfaces in a multifield two‐fluid model

“…The approach is tested for various multiphase scenarios: an ethanol droplet in equilibrium, a dam break, a rising gas bubble, a dispersed flow in a vertical pipe, and a plunging liquid jet. The model is further verified for stratified and slug flow regimes by Colombo et al 14 Overall a significant over-estimation of the interfacial shear stress is observed, which is attributed to the interfacial momentum transfer modeling. Especially, the interfacial drag modeling at resolved interfaces is the key to high accuracy in that context.…”

“…In detail, in the buoyancy term r 𝛼 g i 𝜌 𝛼 , that is, in the third term on R.H.S. of Equation ( 2), for each phase sharing the large scale interface the phase-specific density 𝜌 𝛼 is replaced by mixture density 𝜌, which is defined analogously to Equation (14). With that change, the proposed gravity term in Equation ( 2) reads:…”

“…For instance quantities like interface curvature have been used for that purpose by Coste et al 12 and by Wardle and Weller 13 . Overall, the two‐field approach appears to be quite robust, but not particularly accurate and it has been used for various applications 1,2,10,12‐16 . At this point, the recent work of De Santis et al 10 is discussed in more detail, which is based on the approach of Wardle and Weller 13 .…”

“…13 Overall, the two-field approach appears to be quite robust, but not particularly accurate and it has been used for various applications. 1,2,10,[12][13][14][15][16] At this point, the recent work of De Santis et al 10 is discussed in more detail, which is based on the approach of Wardle and Weller. 13 The morphology is adapted based on a binary switch that is coupled to the blending framework implemented in the OpenFOAM Foundation release.…”

State of the Art on Two-Phase Non-Miscible Liquid/Gas Flow Transport Analysis in Radial Centrifugal Pumps Part C: CFD Approaches with Emphasis on Improved Models

“…It was the first time it was adopted for centrifugal pump flow and certainly leaves potential for further improvements. In the literature, more sophisticated hybrid multiphase approaches have been reported, such as the generalized multiphase modeling approach (GEMMA) of De Santis et al and Colombo et al [73,143,144] and the hybrid multi-scale model of Meller et al [79]. The GEMMA model fundamentally deviates from the one described here by including an interfacial drag formulation for large-scale interfaces, which was first proposed by Marschall [75] within the EE2F framework.…”