The optimization of liquid ultrasonic flow meter through modelling and simulation using the Reynolds and Nusselt number, is both a textbook and reference that engineers and technicians will want in their personal libraries. The three main objectives are: 1. A multipath meter with an integration method of velocity profile correction, to improve performance on high viscosity low Reynolds numbers applications. 2. Robustness in correcting asymmetric axial flow velocity profiles. 3. Compensation transverse flow components. Features include techniques such as velocity profile correction, accurate measurement at the lower flow range are shown in simulations.The type of oil samples which were considered are Light, Medium,Brad Penn,Heavy and Extra heavy oils. The use of analogies for modeling fluid flow,thermal and mechanical components. A brief introduction to computational fluid dynamics is presented, while any intelligent computer-literate person can run a CFD code.