ANALYSIS OF TURBULENT FLOW IN CLOSED AND OPEN CHANNELS WITH APPLICATION IN ELECTROMAGNETIC VELOCIMETRY

Electromagnetic velocimetry based on Lorentz force measurements is a new technique developed for liquid metal flow measurements. Numerical calibration of Lorentz force flowmeters requires accurate computations of the velocity distribution for high Reynolds number turbulent flows in ducts and open channels. In this paper, numerical modelling is used to investigate velocity profiles in internal and external turbulent flows at high Reynolds numbers. The numerical results obtained by using the k-epsilon turbulence model are compared to theoretical and experimental data from the literature. It is found that the logarithmic wall law can approximate the velocity profile in closed channel flows. The friction velocities in the logarithmic law are estimated by solving numerically the friction equation. In the case of open channel flows, the dip phenomenon is investigated at various aspect ratios of the channels. After the numerical model validation, flow computations are included in the numerical calibration procedure of the Lorentz force flowmeters. Numerical results show small variations of Lorentz forces due to the non-uniformity of velocity profiles in the case of high Reynolds number turbulent flows.