Particle Capture Rate Research Articles

Capture of colloidal fine suspended particle by aquatic vegetation under rainfall

The capture of colloidal fine suspended particles by vegetation plays an important role in water quality of the shallow aquatic system under rainfall. Quantifying impact of rainfall intensity and vegetation condition on this process remains poorly characterized. In this study, the colloidal particle capture rates under three rainfall intensities, four vegetation densities and with submerged or emergent vegetation were investigated in different travel distance in a laboratory flume. Considering vegetation as porous media, non-Darcy's law with rainfall as a source term, was coupled with colloid first-order deposition model, to simulate the particle concentration changes with time, determining the particle deposition rate coefficient (kd), representing capture rate. We found that the kd increased linearly with rainfall intensity; but increased and then decreased with vegetation density, suggesting the existence of optimum vegetation density. The kd of submerged vegetation is slightly higher than emergent vegetation. The single collector efficiency (η) showed the same trend as kd, suggesting colloid filtration theory well explained the impact of rainfall intensity and vegetation condition. Flow hydrodynamic enhanced the kd trend, e.g., the theoretical strongest flow eddy structure represented in the optimum vegetation density. This study is helpful for the design of wetland under rainfall, to remove colloidal suspended particles and the hazardous material, for the protection of the downstream water quality.

Colloidal transport in anisotropic porous media: Kinetic equation and its upscaling

We discuss three-dimensional suspension-colloidal-nano transport in anisotropic porous media. The Boltzmann kinetic equation captures stochastic particle velocity distribution on the micro-scale due to the stochastic nature of the pore-space geometry. We express the anisotropy by tensorial micro-scale transport coefficients and a direction-dependent velocity distribution. The Bhatnagar–Gross–Krook (BGK) form of Boltzmann’s equation for particle transport with a particle capture rate proportional to the particle velocity is formulated. We introduce an equivalent sink term into the kinetic equation instead of non-zero initial data, yielding an evolution system not requiring Cauchy’s data. Exact probabilistic homogenisation is performed by solution of a functional operator equation in Hilbert space of Fourier images. The homogenised macro-scale model has the form of a three-dimensional advective–diffusive–reactive equation, where the particle flow in all directions is slower than the carrier fluid speed. This delay is the collective result of particle flow and capture and is explained by preferential capture of faster particles. Closed expressions of upscaled transport coefficients as a function of microscale parameters are explicit. For the particular case of quasi-one-dimensional flow, where the average transverse flux is zero, we derive the upscaled equation and investigate the continuous and pulse colloidal injections.

Experimental insight into the silica nanoparticle transport in dolomite rocks: Spotlight on DLVO theory and permeability impairment

Nanoparticles (NPs) have been proposed as a promising agent for groundwater aquifer remediation, greenhouse geological storage, and enhanced oil recovery (EOR) applications. Nevertheless, in many of these cases, NPs applications require long transport distances, which may be limited by NPs retention in porous media, especially at high saline conditions as is the case with some oil reservoirs, causing a reduction in rock permeability and subsequent formation damage. Therefore, understanding of NPs transport through porous media and their stability behavior are significant challenges before their large-scale applications, which has been less explored in previous works. This paper investigates silica NPs transport through dolomite rocks, which are the host rocks of many sub-surface reservoirs. To this end, the stability of silica nanofluids with different concentrations in the presence of different ionic strength and ion types was explored by zeta potential measurement and particle size analysis. NPs adsorption on rock surface was examined by SEM images. The DLVO analysis was conducted to determine the interaction energies between NPs and the rock, and investigate the reversibility of NPs adsorption on the rock. Single-phase coreflooding experiments aided by NPs effluent analysis were performed to obtain breakthrough curves. Results indicated that increasing silica NPs concentration from 0.1 to 0.5 wt% leads to a reduction in nanofluid stability in which the average size of silica NPs increased from 110 to 220 nm. Higher ionic strength (50,000 ppm) decreased nanofluids stability and this negative effect was more pronounced for nanofluids containing MgCl2 salt. It was found that less stable nanofluids showed higher NPs retention through porous media. Highly stable nanofluids exhibited a higher probability of NPs to be detached during the brine post-flushing stage. As to the results of silica nanofluid injection in dolomite rock, increase of the silica NPs concentration and decrease of their stability in suspension were two causes of the rock permeability impairment; a 10% reduction in rock permeability was observed by 0.1 wt% salt-free silica nanofluid, whereas it decreased by 87% using 0.5 wt% of saline nanofluids prepared by 50,000 ppm MgCl2. According to the interpretations based on the deep bed filtration model, the higher salinity of nanofluid is, the higher filtration coefficient would be, meaning that the higher rate of particle capture at higher salinities. Also, no internal/external filter cake was formed and instead, the pore filling process was found to be the major mechanism of the permeability impairment by silica NPs.

Design and Numerical Simulation of Biomimetic Structures to Capture Particles in a Microchannel

The study of separating different sizes of particles through a microchannel has been an interest in recent years and the primary attention of this study is to isolate the particles to the specific outlets. The present work highly focuses on the design and numerical analysis of a microchip and the microparticles capture using special structures like corrugated dragonfly wing structure and cilia walls. The special biomimetic structured corrugated wing is taken from the cross-sectional area of the dragonfly wing and cilia structure is obtained from the epithelium terminal bronchioles to the larynx from the human body. Parametric studies were conducted on different sizes of microchip scaled and tested up in the range between 2–6 mm and the thickness was assigned as 80 µm in both dragonfly wing structure and cilia walls. The microflow channel is a low Reynolds number regime and with the help of the special structures, the flow inside the microchannel is pinched and a sinusoidal waveform pattern is observed. The pinched flow with sinusoidal waveform carries the particles downstream and induces the particles trapped in desired outlets. Fluid particle interaction (FPI) with a time-dependent solver in COMSOL Multiphysics was used to carry out the numerical study. Two particle sizes of 5 µm and 20 µm were applied, the inlet velocity of 0.52 m/s with an inflow angle of 50° was used throughout the study and it suggested that: the microchannel length of 3 mm with corrugated dragonfly wing structure had the maximum particle capture rate of 20 µm at the mainstream outlet. 80% capture rate for the microchannel length of 3 mm with corrugated dragonfly wing structure and 98% capture rate for the microchannel length of 2 mm with cilia wall structure were observed. Numerical simulation results showed that the cilia walled microchip is superior to the corrugated wing structure as the mainstream outlet can conduct most of the 20 µm particles. At the same time, the secondary outlet can laterally capture most of the 5 µm particles. This biomimetic microchip design is expected to be implemented using the PDMS MEMS process in the future.

On predicting particle capture rates in aquatic ecosystems.

Recent advances in understanding the capture of moving suspended particles in aquatic ecosystems have opened up new possibilities for predicting rates of suspension feeding, larval settlement, seagrass pollination and sediment removal. Drawing on results from both highly-resolved computational fluid dynamics (CFD) simulations and existing experimental data, we quantify the controlling influence of flow velocity, particle size and collector size on rates of contact between suspended particles and biological collectors over the parameter space characterising a diverse range of aquatic ecosystems. As distinct from assumptions in previous modeling studies, the functional relationships describing capture are highly variable. Contact rates can vary in opposing directions in response to changes in collector size, an organism’s size, the size of particles being intercepted (related to diet in the case of suspension feeders), and the flow strength. Contact rates shift from decreasing to increasing with collector diameter when particles become relatively large and there is vortex shedding in the collector wake. And in some ranges of the ecologically relevant parameter space, contact rates do not increase strongly with velocity or particle size. The understanding of these complex dependencies allows us to reformulate some hypotheses of selection pressure on the physiology and ecology of aquatic organisms. We discuss the benefits and limitations of CFD tools in predicting rates of particle capture in aquatic ecosystems. Finally, across the complete parameter space relevant to real aquatic ecosystems, all quantitative estimates of particle capture from our model are provided here.

Exact solution for 1D deep bed filtration with particle capture by advection and dispersion

We consider a one-dimensional (1D) non-linear 2x2 hyperbolic problem of suspension-colloidal-nano transport in porous media, so-called deep bed filtration. The particle capture rate is proportional to the overall particle flux, which includes dispersion. The captured-particle concentration dependency on the proportionality coefficient, which is typical for large captured concentrations, causes the non-linearity of the problem. However, the 1D initial–boundary value problem allows for an exact solution. The introduction of the Riemann invariant converts the 2x2 system into a scalar quasi-linear hyperbolic equation, which is implicitly solved using the method of characteristics. The non-linear equation for particle capture rate yields a limited travelling wave that approximates the exact solution for the initial–boundary problem.

Boltzmann's colloidal transport in porous media with velocity-dependent capture probability

Mathematical modeling of suspension-colloidal-nano transport in porous media at different scales has long been a fascinating topic of fluid mechanics. In this study, we discuss the multi-pore scale, where Boltzmann's approach of distributed velocities is valid, and average (homogenize) the micro-scale equation up to the core scale. The focus is on the filtration function (particle capture probability per unity trajectory length) that highly depends on the carrier fluid velocity. We develop a modified form of the Boltzmann equation for micro-scale particle capture and diffusion. An equivalent sink term is introduced into the kinetic equation instead of non-zero initial data, resulting in the solution of an operator equation in the Fourier space and an exact homogenization. The upper scale transport equation is obtained in closed form. The upscaled model contains the dimensionless delay number and large-scale dispersion and filtration coefficients. The explicit formulas for the large-scale model coefficients are derived in terms of the micro-scale parameters for any arbitrary velocity-dependent filtration function. We focus on three micro-scale models for the velocity-dependent particle capture rate corresponding to various retention mechanisms, i.e., straining, attachment, and inertial capture. The explicit formulas for large-scale transport coefficients reveal their typical dependencies of velocity and the micro-scale parameters. Treatment of several laboratory tests reveals close match with the modeling-based predictions.

Averaged Boltzmann’s Kinetics for Colloidal Transport in Porous Media

AbstractDue to the stochastic nature of pore space geometry, particle velocities in a colloidal‐suspension flux are also stochastically distributed. This phenomenon is captured by Boltzmann's kinetic equation. We formulate a BGK‐form of Boltzmann's equation for particulate flow with a particle capture rate proportional to the particle speed and derive an exact method for the model's averaging. The averaged equation is of the form of a reaction‐advection‐diffusion equation with the average particle speed lower than the carrier fluid velocity. This delay, reported in numerous laboratory studies, is explained by preferential capture of fast particles. The large‐scale model coefficients of delay, dispersion, and filtration are explicitly expressed via the microscale mixing length, equilibrium velocity distribution, and filtration coefficient. The properties of the averaged coefficients are discussed, and emerging dependencies between them are presented. The derived large‐scale equation resolves two paradoxes of the traditional model for suspension‐colloidal transport in porous media. The large‐scale equation closely matches the laboratory breakthrough curves.

Modelling of particle capture by expanding droplets

Abstract

Predicting the aerosol capture characteristics of fibrous filters. I. Exact- and tractable (3-moment) approximate-methods to incorporate aerosol polydispersity effects with a multi-mechanism, semi-analytic single-fiber particle capture fraction

We exploit recent results for the multi-mechanism capture of aerosols by an isolated fiber in a steady low-Re crossflow, and analyze the consequences of aerosol polydispersity on the local particle capture rate per unit volume within a “deep” and spatially uniform fibrous filter medium. The linear first-order PDE governing evolution of the aerosol size distribution (ASD) function, n(v;z), within such an idealized medium (where v is particle volume and z the axial distance measured into the fibrous filter) is shown to admit exact solutions by a method of successive quadratures, free of restrictive assumptions about the functional form of either the inlet or internal ASD, or the local, multi-mechanism single fiber capture fraction, ηcap(v). This solution not only provides access to the usual measure of filter performance—i.e., fraction of the inlet mass (or volume) flow rate which is captured, but enables the accuracy of potentially attractive rational approximate methods to be studied. As examples, when the suspended local ASD is, and remains, single-mode log-normal-like, we formulate and examine the accuracy and efficiency of two tractable, mathematically closed, 3-moment methods for predicting the overall performance of ‘thick’ (LF/df≫1) non-woven filters comprised of fibers of a single diameter in a uniform ‘matte’ of small solid-fraction, ϕf. To fix ideas, we illustrate our present theoretical-computational methods, and some of their practical implications, for the particular case of a LF/df=300 filter comprised of 2.5 μm diam. glass fibers challenged by an aerosol population of spherical KCl(s) particles under conditions close to those experimentally studied (and computationally simulated using Brownian-dynamics + CFD methods) in the recent literature. We first consider a ‘coagulation-aged’ aerosol population having an entrance volume fraction of 0.1×10-6 with dp,g=200 nm, suspended in a U0=15 cm/s airstream (at p=1 atm, 300 K, Brownian diffusion dominated and interception influenced conditions). To demonstrate the expected improvement in filter efficiency near the previous maximum penetration particle size (MPPS) (ca. 500 nm diam) via the onset of sub-critical particle inertia effects, we also consider a carrier gas velocity of 200 cm/s, revealing a ca. 10-fold gain in local capture efficiency. Such improvements, while offset by the increased penetration of much smaller particles, should be attainable in many fibrous filter applications, provided the associated increase in gas pumping power remains manageable. We conclude with our current assessment of the relative advantages of each of the predictive methods developed and explored here. Tractable generalizations of our essentially deterministic, pseudo-continuum methods—e.g., to enable inclusion of the systematic effects of accessible fiber diameter and orientation distributions also appear to be feasible—as briefly outlined in Section 5.

Bichromatic dark trap immersed in a buffer gas with an admixture of resonant atoms

The quasiclassical kinetic theory of optical forces has been applied to describe the kinetics of accumulation, deep trapping and cooling of particles in a bichromatic dark trap (BDT), which is placed into a reservoir with a thermal gas at room temperature containing an admixture of resonant atoms. BDT (proposed in our previous works, Krasnov 2016 Laser Phys. 26 105 501, 2017 27 085 501) is a multiple-optical-beam dark trap, in which rectified gradient forces in a bichromatic light field are used to manipulate the particles. The purpose of the present study is to investigate the possibility of direct BDT loading from the equilibrium gas mixture which will result in trapping and cooling of a sufficiently great amount of atoms by BDT. We derived a reduced Fokker-Planck equation in the energy space (for the Wigner particle distribution function) including the collision term. This equation takes into account the optical trapping force, its quantum fluctuations, particle loss from the trap and weakly-dissipative nature of BDT. Its asymptotic solution allows one to describe the particle kinetics and obtain explicit formulas for the main characteristics of BDT (particle capture rate into BDT, temperature and number of the trapped particles). Ultimately, we demonstrate the high efficiency of the particle accumulation in BDT. In particular, the concentration of the trapped particles (with the temperature at least by four orders of magnitude lower than the room temperature) has been shown to be able to exceed the concentration of the ‘hot’ untrapped particles by several dozens of times, and it has been demonstrated that the accumulation efficiency can reach the values of the order of 103.

Changes in Food Selection through Ontogeny in Crassostrea gigas Larvae

Bivalves are some of the most important suspension feeders in aquatic systems. Much research has been conducted on the feeding mechanisms of adult molluscan suspension feeders, but less is known about the feeding mechanisms of their larval stages. To date, the general consensus is that veligers are restricted to collecting particles 4-20 μm in size and that food selection is indiscriminate within this size range, but this hypothesis remains to be directly tested. Therefore, we experimentally assessed this assumption by quantifying microalgal particle capture rates for the larvae of the Pacific oyster (Crassostrea gigas) when fed five different microalgal species individually and in combination. We then tested whether factors such as cell size affected capture rate and consumption, as well as whether capture rate was affected by the presence of other microalgal species. We found evidence of food preference that was not simply a function of size or relative nutritional quality for C. gigas veligers. Further, we found that food selectivity changed through ontogeny. To our knowledge, the changes in selection that we observed through ontogeny have not been previously reported. Interestingly, there was also a sharp decrease in the variability among replicates in consumption rate as the larvae aged. Whether this is a function of velar structure or larval size remains to be tested. Our results suggest some underlying process resulting in certain species of microalgae being captured and consumed at significantly different rates than others.

Crab burrow aspect ratio influences particle capture rates on intertidal sandflats

Crabs are ecosystem engineers that dig burrows, which can trap sediment. We used a field experiment to explore how burrow aspect ratio (depth/diameter) affects the trapping efficiency of sediments and organic material. Arrays of burrows mimics were constructed using tubes of similar depths but two different opening diameters: fat tubes (aspect ratio of 3.8) and thin tubes (7.1). Different arrays were tested to examine whether the combination of burrows with two different aspect ratios affects the material capture, while retaining the same total area of openings per array. The results showed that, in general, the fat tubes trapped more organic material, especially large pieces, and more sediment than thin tubes. Furthermore, the silt-clay content of the sediment trapped in the tubes was up to 50% greater than the surrounding surficial sediment. Hence, we conducted 2D numerical simulations of flow around, and into, a single burrow to elucidate the mechanisms behind particle capture. Results showed that the flushing rate and the turbulent kinetic energy were greater in the fat tubes. However, turbulence persisted for a longer distance downstream of the thin tubes than the fat tubes. The enhanced turbulence may increase the flux of sediment into the tubes where particles can settle and, consequently, promote the sediment capture and sedimentation rate. Our results demonstrate that the aspect ratio of burrows significantly affects capture processes of organic material and sediment particles. Moreover, this capture mechanism depends on the flow regime, as faster flows are associated with larger amounts of material in the water column.

The role of pulverized coal drying temperature in fly ash carbon content and slagging of a tangentially coal-fired boiler

The purpose of this paper is to investigate the effect of the pulverized coal drying temperature on fly ash carbon content and slagging of a 1000 MW unit coal-fired boiler. The pulverized coal was dried at three selected temperatures of 25 °C, 75 °C and 110 °C, and the moisture and porosity of the pulverized coal particles were measured. Based on the porosity range obtained from the measurement, 3-D steady numerical simulation of combustion in tangentially coal-fired furnace was conducted by use of Fluent Software. It was found, (1) The porosity, specific surface area and pore diameter of pulverized coal particles increase with the increase of pulverized coal drying temperature. (2) The increase in the pulverized coal porosity led to the lower flame center and the lower temperature in over-fired air zone. (3) The fly ash particle capture rate and the fly ash carbon content decreased when the pulverized coal porosity increased. (4) The slagging of water wall presents a downward trend with the growth of the pulverized coal porosity. The slagging problem is well resolved in a power plant after applying the strategy of heating up pulverized coal when burning highly slagging tendency coal.

Cotransport of Suspended Colloids and Nanoparticles in Porous Media

The objective of this study is to develop a model for cotransport of colloids and nanoparticles (NPs) in porous media under two particle capture mechanisms. The particle capture rate is proportional to the capture probability, which is a function of retained concentration, called the filtration function. Laboratory bench-scale experiments of individual transport of NPs and colloidal-size kaolinite clay particles through packed columns produced breakthrough curves (BTCs) that monotonically increased with time and stabilised at some value lower than the injected concentration. We discuss the filtration function that corresponds to BTCs stabilising at the concentration lower than the injected value. This so-called binary filtration function incorporates two particle capture mechanisms. The analytical transport model with a binary filtration function was capable to fit successfully BTCs obtained from individual transport experiments using kaolinite and NPs conducted by Chrysikopoulos et al. (Transp Porous Med 119(1):181–204, 2017). Assuming that the electrostatic particle–solid matrix interaction and the fraction of the solid matrix surface area occupied by a single attached particle (kaolinite or NP) are the same for individual transport of either kaolinite particles or NPs and for simultaneous cotransport of kaolinite particles and NPs, the proposed binary filtration function was extended for the cotransport case. Although the breakthrough data from cotransport experiments with kaolinite particles and NPs have six degrees of freedom, the developed cotransport model successfully matches the BTCs by tuning two constants only. This validates the developed model for cotransport of two colloidal populations with different attachments and straining rates.

Nanoscale Functionalized Particles with Rotation-Controlled Capture in Shear Flow.

Important processes in nature and technology involve the adhesive capture of flowing particles or cells on the walls of a conduit. This paper introduces engineered spherical microparticles whose capture rates are limited by their near surface motions in flow. Specifically, these microparticles are sparsely functionalized with nanoscopic regions ("patches") of adhesive functionality, without which they would be nonadhesive. Not only is particle capture on the wall of a shear-chamber limited by surface chemistry as opposed to transport, but also the capture rates depend specifically on particle rotations that result from the vorticity of the shear flow field. These particle rotations continually expose new particle surface to the opposing chamber wall, sampling the particle surface for an adhesive region and controlling the capture rate. Control studies with the same patchy functionality on the chamber wall rather than the particles reveal a related signature of particle capture but substantially faster (still surface limited) particle capture rates. Thus, when the same functionality is placed on the wall rather than the particles, the capture is faster because it depends on the particle translation past a functionalized wall rather than on the particle rotations. The dependence of particle capture on functionalization of the particles versus the wall is consistent with the faster near-wall particle translation in shearing flow compared with the velocity of the rotating particle surface near the wall. These findings, in addition to providing a new class of nanoscopically patchy engineered particles, provide insight into the capture and detection of cells presenting sparse distinguishing surface features and the design of delivery packages for highly targeted pharmaceutical delivery.

Determining model parameters for non-linear deep-bed filtration using laboratory pressure measurements

Particle capture in porous media and the consequent permeability reduction occur in oilfields during water injection or produced water re-injection, migration of mobilized reservoir fines, and invasion of drilling and completion fluids into formations. Reliable modelling-based prediction of particle propagation in natural reservoirs is an essential step in the planning and design of waterflooding.The mathematical model for suspension-colloidal transport in natural reservoirs contains two empirical functions of retained particle concentration. The filtration function expresses the particle capture rate. The formation-damage function determines the permeability decline due to particle capture and retention. Previous works developed an inverse-problem solution to recover both functions from breakthrough concentration and the pressure drop. The present paper develops a new method that determines the filtration and formation-damage functions from pressure measurements only. The method uses pressure data at an intermediate point of the porous column (core), which supplements pressure measurements at the core inlet and outlet. The proposed method furnishes two retained-concentration functions for filtration and formation-damage. The method is validated by comparison with laboratory experiments. A high fit with the pressure data at three core points was observed. Moreover, the fitted model predicts the pressure measured at other core points with high precision.

Deterministic droplet-based co-encapsulation and pairing of microparticles via active sorting and downstream merging.

Co-encapsulation of two distinct particles within microfluidic droplets provides the means to achieve various high-throughput single-cell assays, such as biochemical reactions and cell-cell interactions in small isolated volumes. However, limited by the Poisson statistics, the co-encapsulation rate of the conventional co-flow approach is low even under optimal conditions. Only up to 13.5% of droplets precisely contain a pair of two distinct particles, while the rest, either being empty or encapsulating unpaired particles become wastes. Thus, the low co-encapsulation efficiency makes droplet-based assays impractical in biological applications involving low abundant bioparticles. In this paper, we present a highly promising droplet merging strategy to increase the co-encapsulation efficiency. Our method first enriches droplets exactly encapsulating a single particle via fluorescence or scattering-light activated sorting. Then, two droplets, each with a distinct particle, are precisely one-to-one paired and merged in a novel microwell device. This deterministic approach overcomes the Poisson statistics limitation facing conventional stochastic methods, yielding an up to 90% post-sorting particle capture rate and an overall 88.1% co-encapsulation rate. With its superior single-particle pairing performance, our system provides a promising technological platform to enable highly efficient microdroplet assays.

Mineralization kinetics of air bubbles allowing for the particle detachment and time of buoying of aggregates

The joint consideration of subprocesses of particle capture and detachment, and buoying of aggregates in the periodic nonfrothing flotation conditions shows that the mineral load formed on a separate part for its buoying time (τm). This load is a part of the equilibrium mineral load, which can be attained under the infinite mineralization time. It is proposed to characterize the composition and attainment rate of the mineral load by two dimensionless parameters, which depend on intensities of subprocesses. The sort parameter of particles (B) has been uniquely determined by the ratio of the detachment intensity to the capture intensity, while the dimensionless time (D) is determined by the ratio of the particle capture and detachment rate to the buoying velocity of the air bubble. The mineralization kinetic equation by many bubbles is derived in the exponential form similarly to the first-order Beloglazov equation. Intensities of capture and detachment subprocesses in the mineralization rate constant (K m) determine the magnitude of recovery by a separate bubble (ebm) for time τm, while the air consumption determines the summary recovery e.

Dynamics of Magnetic Nanoparticles in Newly Formed Microvascular Networks Surrounding Solid Tumours: A Parallel Programming Approach

In this paper we extend a previous 2D parallel implementation of a continuous-discrete model of tumour-induced angiogenesis. In particular, we examine the transport and capture of magnetic nanoparticles through a newly formed vascular network of blood vessels. We demonstrate how our models can be used to describe the dynamics of magnetic nanoparticles in a microvasculature and observe that the orientation of the blood vessels with respect to the magnetic force crucially affects particle capture rates leading to heterogeneous particle distributions. In addition, efficiency of magnetic particle capture depends on the ratio between the magnetic velocity and blood vessel aspect ratio. Such simulations allow a more detailed understanding of the use of magnetic nanoparticles as a mechanism for targeted anti-cancer drug delivery.