Abstract:
A simplified two-dimensional finite volume axisymmetric mesh was constructed that represented the geometry of the Kamioka Liquid scintillator Anti-Neutrino Detector (KamLAND) experiment in order to perform a computational fluid dynamics (CFD) analysis of the purification process of the liquid scintillator (LS). 1,000 tons of the LS, contained within a 13 meter-diameter spherical balloon in the center of the detector, is purified in a continuous process where the LS is simultaneously withdrawn from the bottom and replaced at the top of the detector. During this purification process, the interface between the newly purified and unpurified LS is not stratified horizontally as expected, but instead mixing is observed, reducing the efficiency of the process and preventing the desired level of purification throughout the LS. Using the commercial CFD software FLUENT, the purification process of the experiment was simulated based on the conditions and data previously recorded during the purification phase. The CFD analysis of the experiment was modeled as a transient problem, with flow and heat transfer solved. The phenomenon of natural convection was modeled using the Boussinesq approximation. The volume of fraction (VOF) method was used to track the interaction between the purified and unpurified liquids in the simulation. The CFD simulation will be used to test proposed improvements to the purification process for future purification programs of KamLAND. The CFD simulation will serve as a guide to test these improvements and improve the efficiency of the process.
