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

The cross-flow in a staggered tube bundle is computed with an LES and a transient Reynolds stress transport model (RSTM) in 2D and 3D, with two levels of grid refinement. The numerical method is based on a finite volume approach on unstructured grids using a collocated arrangement for all the unknowns. It is shown that the LES results on the fine mesh are comparable to a DNS and experiments and reasonable agreement is still achieved with a coarse mesh. The RSTM also produced satisfactory results in 3D but showed no advantage over the LES when the grid was coarsened. The 2D RSTM, which produced strong vortex shedding, was found to be physically unreasonable.