Orbitally shaken bioreactors (OSRs) are commonly used for the cultivation of mammalian cells in suspension. Here we conducted a three-dimensional computational fluid dynamics (CFD) simulation to characterize the fluid field in the disposable 600-mL orbitally shaken bioreactor (OSR600), basically a cylindrical vessel with a conical bottom and a ventilated cap. The CFD models established for the OSR600 were validated by visual comparison of the liquid flow pattern, in an experimentally agitated OSR600. In the model, both shear stress and energy dissipation rate (Phi) were calculated to evaluate the hydrodynamic stress environment for cell cultivation. The highest values of shear stress and Phi were localized along the lower part of the conical vessel wall. The effect of filling volume and shaking speed on k(L)a, Phi and shear stress were also analyzed. An increase of the percentage of the liquid affected by higher shear stress and Phi was observed at filling volumes of 300 mL and 400 mL compared to lower filling volumes. This may be due to the twisted curvature at the base of the liquid wave under these conditions. In conclusion, the CFD model provided a means to characterize the fluid dynamics of the OSR600 under various operating conditions to help identify those most suitable for cell cultivation. (C) 2017 Elsevier B.V. All rights reserved.