Computational fluid dynamics (CFD) has been actively used to make flow profile predictions in down hole oil and gas environments. The flow in oil wells inherently consists of oil, water, and gas phases. Flow profile predictions are complicated by parameters such as fluid properties, flow velocities, area, and well inclination. A proper understanding of flow behavior under various operating conditions is critical when designing down hole equipment and flowmetering applications. This paper presents case studies involving the three-phase flow of oil-water-gas in a down hole tubular. Phase distribution is analyzed for different compositions by varying the individual phase volume fractions. Various flow regimes, such as stratified flow, homogeneous flow, and bubbly flow, are studied individually as well as in their transition from one regime to another. The transition criteria were also studied. Extensive efforts were focused on understanding random bubble distribution, bubble breakup, bubble-relative movement, distortion, and diffusion in fluid flow with respect to flow variables. Finite volume phase distribution for oil vs. water is obtained as a function of time and distance (coherence) for multiphase flow in production tubulars. The effect of geometry changes with the objective of flow homogenization is also studied to enable the locations and numbers of monitoring devices to be fixed. CFD results were found to be comparable to single-phase analytical solutions. The examples and references included in the paper demonstrate the accuracy of the study results. The studies verify that an understanding of flow dynamics is essential to evaluate optimum configurations of the variables described. Advanced knowledge of flow characteristics enables engineers to deliver robust and maintenance-free sensing technology for use in a subterranean environment.