Numerical method for analysis of the correlation between ferrofluid optical transmission and its intrinsic properties

Abstract

A numerical method to simulate the ferrofluid particle distribution evolution is presented. Also, the optical transmission of the distributions obtained is calculated by two numerical methods. The first one consists on a numerical propagation of an electromagnetic wave through the sample. The second one analyzes the aggregates' mean length to obtain the optical transmission through a mixture law. As an illustration of the possibilities of the method developed, it is applied to analyze how ferrofluid optical transmission changes after magnetic field application depend on intrinsic properties of the colloid such as its nanoparticle concentration and surfactant repulsion represented by means of the final distances between consecutive particles forming chains. Changes in the attenuation factor of these samples show the trends expected from the Literature.

Numerical calculation of ferrofluid optical transmission evolution after magnetic field switch-on

“…A computer program developed by us [26] has been used to simulate the nanoparticle distribution evolution immediately after magnetic field switch-on. The most relevant interactions between particles are calculated in order to obtain the evolution of their positions, speeds, and magnetic dipole orientations.…”

“…This size has been selected from the compromise between simulating the highest possible number of particles and taking an assumable computational time. In order to carry out comparisons to experiments, the nominal parameters of the sample employed in [26] have been introduced to the program. Particles have been considered as spheres with a magnetic core of magnetite with radius R n = 50 nm (saturation magnetization M s = 30 emu g −1 indicated by the manufacturer, density 5170 kg m −3 [27]).…”

“…This value has been considered after TEM imaging of the particles [25]. A spherical polymeric coating (density 983.6 kg m −3 , calculated from its composition fully detailed in [25,26]) surrounds the magnetic core so that the complete particle has a hydrodynamic radius R h = 92 nm (as indicated by the manufacturer, measured by Dynamic Light Scattering technique). The particle polydispersity, PdI = 0.176, indicates that the sample is close to being considered monodispersed, so particles have been simulated as identical spheres for simplicity.…”

Influence of size polydispersity on magnetic field tunable structures in magnetic nanofluids containing superparamagnetic nanoparticles

“…Several robust theoretical and numerical formalisms have been developed to understand the interparticle interactions under an external magnetic field in magnetic nanofluids under different conditions [43]. Studies have been undertaken on structure formation in magnetic fluids using…”

“…Several robust theoretical and numerical formalisms have been developed to understand the interparticle interactions under an external magnetic field in magnetic nanofluids under different conditions. 43 Studies have been undertaken on structure formation in magnetic fluids using Brownian dynamics, 44 Monte Carlo simulation, 45 molecular and stochastic dynamic simulations, 46,47 and models based on thermodynamic theory. 48 …”