The enhanced capabilities of Oscillating/Pulsating Heat Pipes (OHPs/PHPs) are often curtailed by a gamut of factors that affects their optimum thermal performance. These factors ranging from their design parameters to operating conditions may not make it feasible to develop experimental prototypes through trial and error as optimum thermal performance cannot be ascertained a priori. In this study, an Eulerian Volume of Fluid (VOF) model coupled with a Level Set Method has been used to numerically investigate the thermal performance of a five-turn water based CLOHP with volume fractions 0.3, 0.5 and 0.7 in vertical and horizontal modes. The capabilities of this computational fluid dynamics (CFD) approach to help predict the optimum thermal performance of OHP/PHPs is well established in literature. A summary of the results from this investigations show that more convective heat transfer rate occurs from the liquid phase than from the vapour phase. Also orientation was found to significantly influence pressure distribution within the CLOHPs. Finally it was observed that thermal resistance was significantly influenced by volume fraction/fill ratio rather than by orientation of the device.