Large eddy simulations of jet flow interaction within staggered rod bundles

This work is a numerical investigation of experimental work on dual isothermal jet injection into a staggered rod bundle, mimicking phenomena present in the lower plenum of the very high temperature gas cooled reactor. Large eddy simulations were used to model the unsteady flow of the experimental conditions. As a basis, steady state simulations as well as time averaged comparisons were made with the standard and realizable k–ɛ formulations. Grid sensitivity studies were performed over six grids with the most refined grid comprised of roughly 26.5 million semi-structured polyhedral cells. The continuous wavelet transform was used for instantaneous signal decomposition of results taken within the domain in an effort to devise a better approach to validating CFD predictions of the complex flows in the lower plenum of the VHTR.