Abstract
The presence of a moving interface in two-phase flows challenges the accurate computational fluid dynamics (CFD) modeling, especially when the flow is turbulent. For such flows, single-phase-based turbulence models are usually used for the turbulence modeling together with certain modifications including the turbulence damping around the interface. Due to the insufficient understanding of the damping mechanism, the phenomenological modeling approach is always used. Egorov’s model is the most widely-used turbulence damping model due to its simple formulation and implementation. However, the original Egorov model suffers from the mesh size dependency issue and uses a questionable symmetric treatment for both liquid and gas phases. By introducing more physics, this paper introduces a new length scale for Egorov’s model, making it independent of mesh sizes in the tangential direction of the interface. An asymmetric treatment is also developed, which leads to more physical predictions for both the turbulent kinetic energy and the velocity field.
Highlights
Two-phase flows are widely encountered in nuclear, chemical, and petroleum engineering.Due to the insufficient understanding of the basic mechanisms that govern the two-phase flow, the computational fluid dynamics (CFD) modeling of two-phase systems, where moving interfaces exist, is still challenging, even though many approaches, e.g., the volume of fluid (VOF) method [1], the two-fluid model [2], and the level-set method [3], have been proposed
Instead of regarding y p as a typical cell size or a cell height in a certain direction, it is more proper to refer to y p as a length scale for the turbulence damping around the interface
The widely-used Egorov model was further developed by introducing more physics
Summary
Two-phase flows are widely encountered in nuclear, chemical, and petroleum engineering. The reason is that, in the absence of mechanistic models for turbulence damping, these phenomenological models are a useful tool that advances two-phase turbulent CFD simulations Egorov’s model employs the same treatment for both gas and liquid phases, which is referred to as the symmetric treatment by Frederix et al [12] It has been pointed out by many researchers [10,12,18] that an asymmetric treatment should be introduced to model the different turbulence behaviors on the different sides of the interface. After some in-depth discussions, an asymmetric treatment is proposed for the turbulence damping such that the turbulence behaviors in individual phases could be modeled separately
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