Conductive Fluid And Magnetic Field

Mathematically, it is the coupling of electromagnetic field equation and fluid motion equation. According to Faraday's law of electromagnetic induction, a conductive fluid moving in a magnetic field will generate an induced electromotive force in a circuit that moves with the fluid. If the conductor is an ideal conductor with infinite conductivity, the induced current will be infinite, which is obviously impossible. If the magnetic flux in any motion loop is constant, the magnetic lines of force must move with the fluid, just as the magnetic lines of force and the fluid are firmly glued together. This phenomenon is called the "freezing" effect of the magnetic field, that is, the magnetic field and the fluid are completely frozen. The equation satisfied by the magnetic field at this time is called the "freezing equation". When the conductivity of the fluid is limited, in addition to continuous Joule heat loss, the magnetic field will continue to diffuse from a strong area to a weak area. Therefore, in general, the magnetic field in the conductive fluid is controlled by the freezing effect and will continue to diffuse. The equation satisfied at this time is called the "diffusion freezing equation". The two effects of freezing and diffusion are related to the velocity (v) and scale (L) of the fluid in addition to the electrical conductivity (λ). In electromagnetic fluid mechanics, the dimensionless constant is defined as the magnetic viscosity coefficient. When RM>>1, the freezing effect in the fluid will be dominant; when RM<<1, the diffusion phenomenon will be dominant.