comsol涡流模块.doc

Induction Currents from CircularCoilsIntroductionAtime--harmonicfieldsimulationaswellasatransientanalysis,-,-aseshowstheskineffect,thatis,,useaquasi-icpotentialA:----------σ-∂--A----+∇×(μ–1μ–1∇×A)=σVcoi-l∂t 0r2πrHereμ0isthepermeabilityofvacuum,μrtherelativepermeability,onductivity,-asetheequationreducesto–1–1Vcoil= -----------jωσA+∇×(μ0μr∇×A)icforceactingonregionofspaceΩcanbeobtainedbyintegratingMaxwell’sstresstensoronthedelimitingboundary∂Ω:F=òTndS∂ΩTheForceCalculationfeatureautomaticallyperformstheintegralalongtheboundariesofthedesiredregion,-harmonicregime,,inturn,icfield“shielding”,,,atime-,,theforceisrepulsive(negative).Figure1:ponentoftheinducedcurrentdensityforthetime-::Snapshotoftheinducedcurrentdensity(surfaceplot)icfluxdensity(arrowplot)duringth