Up to the present, typical application fields of a magnetic particle suspension are certainly fluid engineering and magnetic recording engineering. Recently, the field of medical engineering has obtained considerable attention as an application of a suspension composed of magnetic particles, for instance, magnetic hyperthermia therapy and magnetically guided drug delivery system. In the application to a drug delivery system, it may be significantly important to analyse both the behavior of the magnetic particles in a blood vessel and the attachment or trapping characteristics of magnetic particles to targeted site in the situation of a non-uniform applied magnetic field. In the present study, we have elucidated the feasibility of trapping magnetic rod-like particles that flow in a cylindrical pipe in terms of a non-uniform magnetic field generated by a pair of magnetic poles. The main factors governing the trapping characteristics are expected to be the flow field strength, the non-uniform external magnetic field strength and the magnetic interaction between particles. We have performed Brownian dynamics simulations in order to clarify the influence of these various factors on the attachment or trapping characteristics of magnetic rod-like particles to the poles. The employment of a local linearization approximation enables us to apply the Brownian dynamics (BD) method that was fully-developed for a simple shear flow to the present Hagen-Poiseuille flow. In the linearization approximation, the flow field in the vicinity of the magnetic rod-like particle of interest is regarded as being locally a simple shear flow. BD simulations have been conducted for a variety of situations of the governing factors. The main results obtained here are summarized as follows. In the case of a sufficiently small magnetic interaction between the particles, numerous rod-like particles are trapped to the magnetic poles if the influence of a non-uniform magnetic field is sufficiently more dominant than that of the flow field, otherwise the particles flow away along the centerline of the cylindrical pipe without being trapped at the poles. If the magnetic interaction is sufficiently more dominant than both the flow field and the non-uniform magnetic field, the particles aggregate to form densely-packed clusters that flow away in the centerline area of the cylindrical pipe without being trapped to the poles. These characteristics help to clarify that magnetic rod-like particles are not trapped around the magnetic poles unless the non-uniform magnetic field is sufficiently dominant in relation to the other factors. In a favourable situation of weak magnetic interactions, thin chain-like clusters may be formed from several anchored particles trapped at the poles and these tend to incline in the downstream flow direction. From these results, it is seen that the motion of magnetic particles and their trapping characteristics significantly change dependent on the relative magnitude relationship between the flow field strength, the non-uniform applied magnetic field strength and the magnetic particle-particle interaction strength.


Elucidation of the Trapping Characteristics of Magnetic Rod-Like Particles Flowing in a Cylindrical Pipe by Means of Brownian Dynamics Simulations

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

IMECE2020 - Virtual Conference

Supporting the need among researchers worldwide for additional online and multimedia content, ASME now offers the ASME Conference Video Collection. This platform will collect and provide long-term access to conference presentation videos, encompassing all technology areas within ASME's technical conference and events program. About 30,000-40,000 engineers across all mechanical engineering and related disciplines participate in ASME conferences each year. This includes authors of approximately 6,000 to 8,000 technical papers published by ASME, the majority of whom also submit video presentations for our virtual conferences. The video collection will be available as an add-on to existing product packages or as a separate subscription.