LES, coarse LES, and transient RANS comparisons on the flow across a tube bundle

Abstract

This chapter presents the cross-flow in a staggered tube bundle as computed with large eddy simulation (LES) model and the transient Reynolds stress transport model (RSTM) in 2D and 3D with two levels of grid refinement. It is observed that both the approaches yield satisfactory results with LES being slightly more consistent with direct numerical simulation (DNS). The numerical method is generally based on a finite volume approach on unstructured grids using a collocated arrangement for all the unknowns. It is observed that the LES results on the fine mesh are comparable to the direct numerical simulation (DNS), and experiments and good agreement is achieved with a coarse mesh. It is also noted that the RSTM produces satisfactory results in 3D but exhibits no advantage over the LES when the grid is coarsened. Also the 2D RSTM, producing strong vortex shedding is found to be physically unreasonable.