A new model for viscous oil-water eccentric core annular flow in horizontal pipes

•A new mechanistic model for viscous oil-water eccentric CAF in horizontal pipes was developed.•The model enables predicting essential flow characteristics of oil-water core flows over a wide range of operational conditions.•The proposed model shows a better performance than other models available in literature.•The model offers the flexibility of treating cases where the properties of the lubricating phase are different in the two regions.