Large eddy simulation of cross flow over in line and staggered tube bundles

This paper investigates numerically the turbulent flow characteristics in two tube bundle arrangements. More specifically, the steady approaching cross-flow over an in-line tube bundle at Regap = 3,400 is studied with the Large Eddy Simulation (LES) technique using both the standard Smagorinsky model and a dynamic model without test filtering. The second arrangement is that of a staggered tube bundle at Regap = 8,600 which is also studied using the standard Smagorinsky model. The LES results for the mean velocity compare favourably with the LDA measurements of Konstantinidis et al (2000) for the in-line tube array. However, the predicted stream-wise r.m.s velocity increases faster along the stream-wise direction in the flow lane region compared to the experiments. A single mode of alternate vortex shedding with a constant Strouhal number (0.145) is predicted. The LES calculation of the turbulent cross-flow over the staggered tube array gives excellent agreement with the experiments of Balabani and Yianneskis (1996). Two distinct vortex shedding Strouhal numbers (0.37 and 0.49, St = f D/ubulk) are found behind the first row and the second row in agreement with Weaver et al (1993). The size of the recirculation bubble zones is also correctly predicted. The stream-wise r.m.s velocity in the downstream region is more accurately predicted compared to the in-line arrangement due to smaller dependence on the inlet turbulence level. (authors)