  We present a comprehensive numerical analysis of alternative transient
eddy-current flowmetering methods for liquid metals. This type of flowmeter
operates by tracking eddy-current markers excited by the magnetic field pulses
in the flow of a conducting liquid. Using a simple mathematical model, where
the fluid flow is replaced by a translating cylinder, a number possible
alternative measurement schemes are considered. The velocity of the medium can
be measured by tracking zero crossing points and spatial or temporal extrema of
the electromotive force (emf) induced by transient eddy currents in the
surrounding space. Zero crossing points and spatial extrema of the emf travel
synchronously with the medium whereas temporal extrema experience an initial
time delay which depends on the conductivity and velocity of the medium.
Performance of transient eddy-current flowmetering depends crucially on the
symmetry of system. Eddy current asymmetry of a few per cent makes the
detection point drift with a velocity corresponding to a magnetic Reynolds
number $Rm\sim 0.1.$ With this level of asymmetry transient eddy-current
flowmetering can be reliably applicable only to flows with $Rm\gtrsim 0.1.$ A
more accurate symmetry adjustment or calibration of flowmeters may be necessary
at lower velocities.
