The 3D DNS of a Taylor bubble in counter-current flow with a turbulent wake using the Front-Tracking method in TRUST/TrioCFD
Résumé
The understanding of two-phase flows is of key importance for the nuclear industry as they may occur in normal operation, like in the steam generators, or in accidental scenarios, like in the core during a loss of coolant accident (LOCA). Among the variety of regimes that may occur in a two-phase flow, there is the slug flow composed of different kind of patterns. One of them is the Taylor bubble which is a large bubble filling almost the entire section of the vertical channel in which it tends to rise up. The correct simulation of a Taylor bubble is challenging as it can be decomposed in three zones involving different scales and mechanisms.
In this communication, we present simulations of Taylor bubble experiments realized by the THELMA laboratory at the Reactor Engineering Division of Jožef Stefan Institute, Slovenia. These experiments were done using air-water mixture in a vertical pipe with a diameter of 12.4 mm. The simulations were realized with TrioCFD, the open-source CFD code developed at CEA, in Direct Numerical Simulation (DNS) using the Front-Tracking (FT) method for interface tracking. Note that this choice of DNS+FT to simulate a Taylor bubble is particularly scarce in the literature and is a premiere for such conditions.
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