Trajectories and Deposition of Silica Particles on Cylinders in Crossflow With and Without a Magnetic Field

Abstract

To investigate magnetic effects on silica scale deposition, two cylindrical probes with and without magnet insert were placed in a crossflow fluid solution containing dissolved silica, iron ion, and NaCl salt. The differences in silica deposition are reported. To explain the differences on the basis of first principles, a Lagrangian analysis is presented to predict the silica colloidal particle trajectories and deposition onto the probes under the influence of nonuniform magnetic field force and other relevant surface forces including London–van der Waals forces, viscous force, and added mass force. The results of the predication show that the particles made of pure silica can be deflected away from the magnetic probe. However, the particles made of silica–iron can be attracted toward the probe, more so at the magnetic poles than at the midsection of the magnetic probe. These and other results presented can explain all the qualitative differences of scale deposit found experimentally on magnetic and nonmagnetic probes.