Relative errors in evaluating the electromagnetic flowmeter signal using the weight function method and the finite volume method

In the signal analysis of an electromagnetic flowmeter, the weight function method (WFM) involves a numerical integration of products between the magnetic flux density vector, the weight function and the velocity profile function in two-dimensional analysis. The electromagnetic flowmeter signal can also be predicted by solving the governing flowmeter equation by the finite volume method (FVM). The present study is aimed at comparing the calculation accuracies of WFM and FVM. The test flows are fully developed laminar and turbulent flows in a straight pipe under uniformly distributed magnetic field. The calculation accuracies are also compared between different O-type grid systems. It was found that the accuracy of both methods depended strongly on the grid system. In particular, for turbulent flow whose axial velocity component changes very rapidly near the wall, the accuracy of WFM was found to depend strongly on the cell configuration near the electrodes.