Transport of Magnetic Particles Around a Magnetized Wire via a Combination of Experiments and Simulations*

We study the interaction of magnetic particles with a non-uniform magnetic field around a single stainless-steel wire. The present study uses numerical simulations and experiments to investigate the transport of particles over a broad range of conditions: concentration of 0.01 ⩽ c ⩽ 0.1 g/lit, magnetic field of 0.25 - 1 T; and wire diameter 0.8 - 3.17 mm. Two types of nano-particles are studied including a paramagnetic manganese oxide and a diamagnetic Bismuth oxide. The experimental setup consists of a standard cuvette and a wire placed between the two poles of an electromagnet. Experiments show that the paramagnetic particles form vortices close to the wire under the magnetic field, where the magnetic field gradient is high, leading to particle enrichment near the wire. Additionally, as particle concentration increases, the magnetophoresis phenomenon is strengthened due to magnetic convection around the wire. Conversely, the diamagnetic particles are repelled from regions of high magnetic field gradients, resulting in their movement away from the wire. Due to gravitational forces, the diamagnetic particles move downward and settle at the bottom of the cuvette. Furthermore, we find that larger wire diameters enhance the separation process, leading to greater particle enrichment around the wire. This phenomenon occurs as a result of the magnetic gradient produced by the increased surface area of the wire.