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Ito, Kei; Kunugi, Tomoaki*; Ohshima, Hiroyuki
no journal, ,
In this study, the authors develop a new manufactured solution with dynamic interfacial deformation due to a vortex, which is a simplified model of the gas entrainment behavior in a nuclear reactor. The manufactured solution is considered on an axisymmetric system and radial, circumferential and axial velocities and pressure are formulated to satisfy the continuity equation and the boundary condition on an interface. The interfacial dent grows with time and a gas bubble is generated when the lower part of the interfacial dent is pinched off. A preliminary simulation is performed on a coarse mesh to investigate the dynamic interfacial deformation on the velocity field given by the manufactured solution. As a result, a reasonable interfacial shape is simulated at each elapsed time, which implies the developed manufactured solution is a good problem to verify an interface-tracking method.
Ito, Kei; Kunugi, Tomoaki*; Koizumi, Yasuo*; Ohno, Shuji; Ohshima, Hiroyuki
no journal, ,
One thermal-hydraulics issue in a sodium-cooled fast reactor is gas entrainment (GE) phenomena. The authors have developed a numerical simulation code for gas-liquid two-phase flows with a high-precision interface-tracking method. This simulation code employs an unstructured mesh scheme to model structural geometries accurately. As for the interface-tracking method, the authors have developed an innovative method based on the high-precision volume-of-fluid method. As a result of fundamental validations, the developed code shows superior simulation accuracy to conventional codes. For example, with the developed second-order interface gradient calculation method, the developed code provides 20-30% smaller simulation error than the original PLIC method for the slotted-disk revolution problem. The GE phenomena itself are also simulated with the developed code and the quantitative agreements of entrained gas flow rates are obtained between the simulation results are the experimental data.