Cement plays an integral role in maintaining well integrity throughout the life cycle of a well. Successful cementing jobs provide good zonal isolation and ensure strong bonding of cement to the casing and formation. The cementing job success is mainly governed by the fluid displacement efficiency and the degree of contamination with other wellbore fluids. However, displacing fluids downhole over long distances is a complex task that requires understanding of mud-spacer-cement interactions, their rheological behavior, as well as frictional pressure losses and flow regimes. Computational Fluid Dynamics (CFD) has been proven to be a powerful tool for modelling fluid behavior in numerous industries. The use of CFD allows us to model these complexities in a precise and reliable manner, and it can provide tailored solutions for individual cementing jobs to ensure maximum job efficiency and safety. In this study, a state-of-the-art CFD model was created using Ansys Fluent software to examine the displacement efficiency of a cementing job under different conditions in eccentric annuli. The CFD model was validated in single phase simulations using two sets of experimental data. The parameters studied include fluid density and rheology, casing eccentricity, flow rate, wellbore deviation, and casing rotation. The effect of each parameter was analyzed and the data was compiled to provide guidelines for efficient fluid displacement. This study stressed the importance of maintaining density and viscosity hierarchies between the displacing and displaced fluids. The drastic effect of eccentricity on the displacement process was shown, as well as possible solutions to counteract this effect by optimizing fluid properties and flowrates. Furthermore, casing rotation proved to be a valuable tool that enhances the displacement efficiency and can partly mitigate the negative effects of high eccentricity. The CFD model proved to be an invaluable resource for optimizing the cement placement process and can be utilized in a variety of ways to provide specialized solutions for each cementing job.