The need for carbon dioxide reduction and accurate metering of fuel flows have led environmental policies to a new perspective. The application of numerical investigation could be useful to predict the behaviour of meters for using new green fuels, avoiding expensive experimental campaigns. This paper adopts the Eulerian approach to numerically analyse the transient, isothermal, and turbulent flow across an orifice plate flowmeter. Numerical results are validated against an experimental campaign, conducted by the Research Institutes of Sweden (RISE). The validated numerical model is adopted to evaluate the performance of the flowmeter in the case of employing two different innovative fuels (biodiesel). The developed numerical tool has also been applied to the simulation of a dynamic inlet flow rate. The obtained results demonstrate the capability of the numerical model to predict the flow rate for the studied scenarios, as well as the difficulties of the investigated meter in performing under dynamic boundary conditions.