Instability in electromagnetically driven flows. II

Imazio, Paola Rodriguez; Gissinger, Christophe

doi:10.1063/1.4942448

Cited by 11 publications

(4 citation statements)

References 12 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Among the most important differences, one is related to the presence of inlet/outlet boundary conditions, and the other to the very large fluid Reynolds numbers involved, which implies highly turbulent flows. In a second article [16], we will therefore report numerical simulations done at larger Reynolds numbers and with more realistic axial boundary conditions. We will show how the bifurcation described here leads to inhomogeneous flows at larger fluid Reynolds number.…”

Section: Discussionmentioning

confidence: 99%

Instability in electromagnetically driven flows. I

Gissinger¹,

Imazio²,

Fauve³

2016

Physics of Fluids

Self Cite

View full text Add to dashboard Cite

The MHD flow driven by a travelling magnetic field (TMF) in an annular channel is investigated numerically. For sufficiently large magnetic Reynolds number Rm, or if a large enough pressure gradient is externally applied, the system undergoes an instability in which the flow rate in the channel dramatically drops from synchronism with the wave to much smaller velocities. This transition takes the form of a saddle-node bifurcation for the time-averaged quantities. In this first paper, we characterize the bifurcation, and study the stability of the flow as a function of several parameters. We show that the bifurcation of the flow involves a bistability between Poiseuille-like and Hartman-like regimes, and relies on magnetic flux expulsion. Based on this observation, new predictions are made for the occurrence of this stalling instability.

show abstract

Section: Discussionmentioning

confidence: 99%

Instability in electromagnetically driven flows. I

Gissinger¹,

Imazio²,

Fauve³

2016

Physics of Fluids

Self Cite

View full text Add to dashboard Cite

show abstract

“…In that case, the velocity of the flow increases with both the magnitude of the applied field and the rotation rate of the discs. Note however that the fluid velocity is always smaller than the speed of the discs, and can be much smaller if the magnetic field is expelled outside the channel at large magnetic Reynolds number, Rm = RePm [22,23].…”

mentioning

confidence: 99%

1/f noise and long-term memory of coherent structures in a turbulent shear flow

2019

View full text Add to dashboard Cite

A shear flow of liquid metal (Galinstan) is driven in an annular channel by counter-rotating traveling magnetic fields imposed at the endcaps. When the traveling velocities are large, the flow is turbulent and its azimuthal component displays random reversals. Power spectra of the velocity field exhibit a 1/ f α power law on several decades and are related to power-law probability distributions P(τ) ∼ τ −β of the waiting times between successive reversals. This 1/ f type spectrum is observed only when the Reynolds number is large enough. In addition, the exponents α and β are controlled by the symmetry of the system : a continuous transition between two different types of Flicker noise is observed as the equatorial symmetry of the flow is broken, in agreement with theoretical predictions.

show abstract

“…However, the fluid domain in the pump was assumed as a solid, and thus, the MHD effect was ignored in the fluid domain. Gissinger et al [18,19] used the direct numerical simulation method to simulate the liquid metal driven by a travelling magnetic field in a two-dimensional channel (equivalent to the meridian plane of the flow channel of ALIP), and the flow characteristics of the liquid metal under different magnetic field conditions were studied. It is found that there are critical values for Re m and Ha.…”

Section: Introductionmentioning

confidence: 99%

Active Flow Control of the Magnetohydrodynamic Flow in an Annular Linear Induction Pump by Modifying the Driving Electromagnetic Field

Wang,

Zhang

et al. 2024

International Journal of Energy Research

View full text Add to dashboard Cite

The strong coupling between fluid and electromagnetic field in the annular linear induction pump (ALIP) can gradually amplify small disturbance in the fluid field into large-scale vortices. The appearance of the vortices seriously affects the efficiency and reliability of the pump. An active flow control method based on the modification of the driving electromagnetic field is proposed to improve the flow stability. A simplified numerical model of the ALIP is established to simulate the three-dimensional flow in the annular flow channel, and the internal electromagnetic field is modified by using the modulated surface current. The influences of the active flow control method on the flow behavior, pressure pulsation, and energy conversion are, respectively, investigated based on the simulation results. The results show that the modulated surface current can accelerate the vortical evolution. The size and strength of the vortices are suppressed in the modified electromagnetic field. The pressure pulsation low frequency at the ALIP’s outlet is significantly reduced when the modulated surface current density reaches a certain level. The surges in the processes of energy conversion become more gentle within the control method, and the overall energy efficiency is slightly reduced even at the highest modulated surface current density.

show abstract

Instability in electromagnetically driven flows. II

Cited by 11 publications

References 12 publications

Instability in electromagnetically driven flows. I

Instability in electromagnetically driven flows. I

1/f noise and long-term memory of coherent structures in a turbulent shear flow

Active Flow Control of the Magnetohydrodynamic Flow in an Annular Linear Induction Pump by Modifying the Driving Electromagnetic Field

Contact Info

Product

Resources

About