ABSTRACT
In the present work, a turbulent flow across a square in-line tube bundle is computed
using the Unsteady Reynolds Averaged Navier-Stokes (URANS) approach. The pitch
ratio used in the tube bundle configuration is P/D=T/D=1.44 and the Reynolds number
is 70000 based on tube diameter. Both 2D and 3D computational domains are
considered. Turbulence models tested include the standard k–ε model of Jones et al.
[12], the k-ω Shear Stress Transport (SST) model of Menter [10] and the Reynolds
Stress Model of Speziale et al. [11] (SSG). In addition, the recently developed, SST- as C
model by Revell [1] is also tested. The unstructured industrial code Code-Saturne has
been used for the present study. In general, the flow predictions using the 2D grid fail to
capture correctly the general flow physics; while on the other hand, the 3D calculations
give predictions of pressure fields and velocity profiles that are in broad agreement with
both LES results [2] and the more recent experimental data [4]. With regards to
turbulence models, a comparison of the pressure coefficient and velocity profiles
revealed that the SST- as C and RSM models, both seem to give reasonable predictions
of the flow, capturing the asymmetric behaviour of the flow as the reference data. As
expected, the standard κ – ε model fails to capture this behaviour and predicts a rather
symmetric flow field. The pressure spectra from the SST- as C calculation indicates a
single clear peak at around the frequency 45Hz (St=0.84), similar to that observed in
LES predictions. This suggests that both large and small re-circulations coexist on the
wake of centre tubes resulting in the shear stress to be higher in the bottom than on the
top of the tubes.