Abstract
Recently, a new method for controlling vertical acceleration and damping convection by applying an upward magnetization force (Fm) has been developed. To evaluate this method, we numerically simulate thermal convection (Ra=33734) in pure water (5×10−6 Ω−1 m−1) when both an upward and radial magnetization forces act on it inside a real magnet. When −μ02H(dH⁄dz) of vertical magnetic field gradients is 573 T2/m, convection is damped and the maximum velocity decreases by about 50%. Natural convection is damped with increasing −μ02H(dH⁄dz) when −μ02H(dH⁄dz) is below the critical value, 1180 T2/m. At 1180 T2/m, the maximum velocity takes a minimum value, about 1% of the velocity without a magnetic field. Above 1180 T2/m, the contribution from the radial magnetic force becomes dominant. Numerical simulation is also conducted for a lowconducting fluid (29 mass% NaCl solution, 21 Ω−1 m−1) when −μ02H(dH⁄dz)=573 T2/m, and the contribution from magnetization force to suppress convection is larger than that from Lorenz force.
