Gas-liquid bubbly flow in a flat bubble column ("Becker" case with a gas flow rate of 1.61/min) is studied by means of large-eddy simulation (LES) combined with Lagrangian particle tracking with two-way coupling. The unsteady two-phase flow considered is relatively dilute in a global sense, but has higher gas clustering locally. The bubble size, of the order of millimeter, is relatively large compared to the smallest liquid fluctuation scales. It is demonstrated that, in such a setting, a single-phase LES along with the point-volume treatment of the dispersed phase can serve as a viable closure model, even though its application assumptions are not fully met. For the backward momentum coupling we used a "particle-source-in-ball" (PSI-ball) concept, which in essence is a generalization of the conventional particle-source-in-cell (PSI-cell) method as well as template-function based treatment. A high prediction accuracy is achieved in an extensive comparison with classical experimental data, covering not only the mean feature of the flow and transient bubble dispersion patterns, but also the second-order statistics of the liquid which is vital in assessing a closure model and has not been enough addressed in the past RANS-based studies. (C) 2007 Elsevier Ltd. All rights reserved.