A framework for a one-way coupling between population balance equation (PBE) and computational fluid dynamics (CFD) for emulsions undergoing breakup in a turbulent flow-regime is implemented in the open-source CFD package OpenFOAM. The PBE is discretized using a volume conservative scheme. This framework was applied to emulsification of food-grade vegetable oil-in-water emulsions in a Niro Soavi high pressure homogenizer (HPH) with different pressure drops and using oils of varying viscosities. Different breakage rate models were implemented, as well as the model of Becker et al. (2014) which is an extension of the Luo and Svendsen (1996) model to account for the dispersed phase viscosity. The Becker et al. (2014) model was found to give better predictions after three consecutive passes, without the need for additional empirically determined parameters. The multi-scale PBE-CFD modelling approach allowed a detailed analysis of the breakup process in the gap and jet of the HPH valve. (C) 2014 Elsevier Ltd. All rights reserved.