Instability in electromagnetically driven flows Part II

TL;DR

This paper investigates the instability phenomena in electromagnetically driven flows, revealing vortex formation and pulsations at higher Reynolds numbers, with implications for the design and operation of electromagnetic pumps.

Contribution

It demonstrates that at higher Reynolds numbers, the instability manifests as axisymmetric vortex flows with pulsations, extending previous low-Reynolds simulations to more realistic conditions.

Findings

Vortex flow forms at higher Reynolds numbers.

Low-frequency pulsations occur near stability threshold.

Results align with theoretical models and experimental observations.

Abstract

In a previous paper, we have reported numerical simulations of the MHD flow driven by a travelling magnetic field (TMF) in an annular channel, at low Reynolds number. It was shown that the stalling of such induction pump is strongly related to magnetic flux expulsion. In the present article, we show that for larger hydrodynamic Reynolds number, and with more realistic boundary conditions, this instability takes the form of a large axisymmetric vortex flow in the (r,z)-plane, in which the fluid is locally pumped in the direction opposite to the one of the magnetic field. Close to the marginal stability of this vortex flow, a low-frequency pulsation is generated. Finally, these results are compared to theoretical predictions and are discussed within the framework of experimental annular linear induction electromagnetic pumps.