2 C. Jin, I. Potts, D. C. Swailes, M. W. Reeks 1 Introduction Turbulent flow over tube-banks has been traditionally modelled using the Reynolds-Averaged Navier-Stokes (RANS) equations with different turbulence models (see [1, 2, 3, 4, 5]). The flow across tube-banks is very unsteady, characterized by strong vortex shedding and bluff-body wakes. Rodi[6] has demonstrated the difficulty or even impossibility of accurately simulating the flow phenomena using the RANS methodology with the standard k − ϵ turbulence model. The aston- ishingly rapid development of Large-Eddy Simulation (LES) (see [7, 8, 9]) has shown the potential to more accurately simulate simple flow phenomena since LES resolves the large-scale unsteady motion directly and requires only modelling of the universal small-scale turbulence structures. It is still a challenging task for numerical simulations to obtain an accurate prediction of un- steady flow separation at high Reynolds number across a single cylinder, not to mention flow across tube-banks since the flow exhibits strong unsteadiness and complex vortex structures. Whether the dynamic boundary layer around a cylinder is accurately resolved with appropriate numer- ical techniques and resolution (see [10, 11, 12, 13]) is crucial to predicting the unstable region where turbulence is generated, the instability of shear layer ([14]) and the physics of the wake ([15, 16]). Hence the conventional LES of turbulent flows across a single cylinder and tube-banks is an extremely expensive endeavour at high Reynolds number flow ([11, 17]). In recent years, LES has been used to simulate turbulent flows across in-line and staggered tube- banks (see [18, 19, 1, 4, 20, 21, 22]) and demonstrated its feasibility and effectiveness. Barsamian and Hassan[18] carried out a two-dimensional LES calculation of flow over tube bundle arrays using two subgrid scale models and studied the power spectra and bound spectra of drag and lift forces. Later extension in three-dimensional LES by Hassan and Barsamian[19] was used to study velocity profile, power spectra density (PSD) of velocities and forces, auto-correlation functions of streamwise and transverse velocities in a flow past a tube bundle at Reynolds number of 21700 based on the free stream velocity and cylinder diameter. Rollet-Miet et al.[2] performed LES based on a Finite Element Method for a turbulent, incompressible flow around a staggered array of tubes and compared the results with the measurements from Simonin and Barcouda [23]. Beale and Spalding[1] performed an LES of transient flow in a relatively low Reynolds number regime of Re ∈ [30 , 3000] based on the gap velocity and cylinder diameter. Both in-line square and staggered-