Large Eddy simulation (LES) of a three-dimensional tube bundle at Reynolds number of 21,700, based on the inlet velocity and the tube diameter was performed. The numerical predictions were compared with available data. The calculations are consistent with the experimental data. The 'flapping' effect in the tube wake was captured. This investigation indicates that the large Eddy simulation technique can be utilized as a tool in predicting the unsteady behavior of flow in some industrial applications. (C) 2004 Elsevier Ltd. All rights reserved.