A series of two-dimensional (21)), axisymmetrie and three-dimensional (3D) numerical flow simulations using an implicit large Eddy simulation (ILES) are carried out for gravity-driven fluid flows. The results are compared directly with experiments undertaken to test the model. Two-dimensional results show that the Large Eddy algorithm is successful in modelling a gravity current's large scale structure. Examination of the 3D results shows that macroscopic features of the flow (the lobe and cleft instability) observed at the interface between the light and dense fluid are also modelled well. Copyright (c) 2005 John Wiley A Sons, Ltd.