Magnetic control of convection in nonconducting diamagnetic fluids

Inhomogeneous magnetic fields exert a body force on electrically nonconducting, diamagnetic fluids. This force can be used to compensate for gravity and to control convection. The field effect on convection is represented by a dimensionless vector parameter ${\mathbf{R}}_m=({\mu }_0\alpha {\chi }_0{d}^3\Delta T/{\rho }_0\nu D_T)(\mathbf{H}\cdot \mathbf{\nabla }\mathbf{H}{)}_{\mathbf{r}=0}^{\mathrm{ext}},$ which measures the relative strength of the induced magnetic buoyancy force due to the applied field gradient. The vertical component of this parameter competes with the gravitational buoyancy effect and a critical relationship between this component and the Rayleigh number is identified for the onset of convection. Magnetically driven convection should be observable even in pure water using current technology.