Anomalous preasymptotic colloid transport by hydrodynamic dispersion in microfluidic capillary flow

Fridjonsson, Einar O.; Seymour, Joseph D.; Codd, Sarah L.

doi:10.1103/physreve.90.010301

Cited by 13 publications

(9 citation statements)

References 36 publications

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“…SNR was calculated as the mean signal magnitude from these ROIs divided by the standard deviation of signal magnitude from a region outside of the flow column. The SNR for [q 1 , q 2 , q 3 , q 4 , q 5 ] was [70,70,70,60,50] for the beadpack and [200,200,170,130,80] for the bulk, similar for both +q and −q and for all flow rates.…”

Section: Methodsmentioning

confidence: 95%

“…For a gas, e.g., propane with D ∼ 10 −6 m 2 /s [58], v min is on the order of 1 mm/s. Macromolecules and large particles can act as tracers and be sensitive to coherent displacements that are just larger than the particles themselves [59], e.g., for colloids with D ∼ 10 −13 m 2 /s [60] v min ∼ 100 nm/s. For free water, at room temperature with D = 2 × 10 −9 m 2 /s and ∆ = 1 s, the simple estimate √ 2D/∆ predicts v min ≈ 60 µm/s.…”

Section: Introduction To Phase Contrast Velocimetrymentioning

confidence: 99%

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Limits to flow detection in phase contrast MRI

Williamson

Komlosh

Benjamini

et al. 2020

Preprint

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Velocity detection with single pulsed gradient spin echo (PGSE) NMR is known to be limited by diffusion smearing the phase coherence and obscuring dispersive attenuation. We present an equation for the lowest detectable velocity with phase contrast velocimetry which incorporates the signal-to-noise ratio. We show how to best sample q-space when approaching this limit. We confirm that the apparent diffusion/dispersion coefficient can be used to infer fluid velocity for Péclet number Pé > 1. When measuring flow in biological systems we determined that with realistic experimental protocols the limits are roughly 1 µm/s for velocimetry and 300 µm/s for diffusometry.There is a strong interest to measure slow flows in vivo, e.g., measuring microcirculation of blood in capillary networks [6] and advective transport in the glymphatic system [7,8]. Knowledge of the lower limit of velocity resolution, as well as how to best measure slow velocities with PGSE MRI may open the door for these and other new applications. General TheoryOne beautiful aspect of magnetic resonance is the multitude of information which can be encoded into its complex signal. Pulsed gradient spin echo (PGSE) NMR exemplifies this in the solution to the Bloch-Torrey equations for the normalized complex signal E(q) arising from a fluid undergoing self-diffusion and coherent flow [9, 10, 11, 1],in which q sensitizes the signal to displacement during an observation time ∆. With rectangular gradient pulse shapes of amplitude g and duration δ, in the case that δ << ∆, q = γgδ where γ is the gyromagnetic ratio of the nuclei. Equation (1) shows that the phase shift between the real and imaginary channels and the attenuation of the signal intensity provide the ability to measure both mean coherent velocity, v, and random diffusion,

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Section: Methodsmentioning

confidence: 95%

Section: Introduction To Phase Contrast Velocimetrymentioning

confidence: 99%

Limits to flow detection in phase contrast MRI

Williamson

Komlosh

Benjamini

et al. 2020

Preprint

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“…The systems studied in this work are in the preasymptotic hydrodynamic dispersion regime (i.e. Δ o oR 2 /D 0 , for water: R 2 /D 0 ¼7.2 s with D 0 ¼2.2 Â 10 À 9 m 2 /s, for colloidal particles: R 2 /D SES ¼23.1 h with D SES ¼1.7 Â 10 -13 m 2 /s (Fridjonsson et al 2014b)). Fig.…”

Section: Methodsmentioning

confidence: 99%

“…These NMR "active" particles have previously been studied with NMR to measure the diffusion characteristics of the internal oil (Wassenius et al, 2003) and velocimetry Callaghan, 2004, 2005). They have been used to demonstrate irreversibility of particle motion at dilute concentrations (Brown et al, 2007), shear induced migration in capillaries (Brown et al, 2009) and hydrodynamic dispersion in microcapillaries (Fridjonsson et al, 2014b). They have also been used to study deposition in porous media (Fridjonsson et al, 2014a), flow partitioning in bifurcations (Fridjonsson et al, 2011), effects of oscillatory flow (Evertz et al, 2012) and transport dynamics in open cell polymer foams (Brosten et al, 2010).…”

mentioning

confidence: 99%

Colloid particle transport in a microcapillary: NMR study of particle and suspending fluid dynamics

Fridjonsson¹,

Seymour

2016

Chemical Engineering Science

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HIGHLIGHTSNMR 'active' colloidal particles at 22 vol% flowed through a μ-capillary Simultaneous measurement of particle and suspending fluid phase dynamics Dynamics of suspending fluid contains particle structure information Shear induced migration within μ-capillaries Results provide experimental data for further investigation and model verification Microcapillary Colloids NMR Hydrodynamic dispersion Particle dynamics ABSTRACT Precise manipulation of the hydrodynamic interaction between particles is particularly important for operation of microfluidic devices. Shear-induced migration gives rise to dynamical patterns within the flow that have been observed in a range of systems. In this work NMR 'active' colloidal particles (a¼1.25 mm) at volume fraction of 22% in an aqueous phase are flowed through a m-capillary (R¼126 mm) and the transport dynamics of the particle and suspending fluid phases are studied using dynamic NMR techniques. Simultaneous interrogation of shear rheology of the suspending fluid and particle phases of colloidal suspensions is presented. The dynamic behavior of the suspending fluid is shown to carry within it information about the structure of the colloidal particle ensembles on the time scales in-vestigated (Δ¼25 ms-250 ms) providing rich experimental data for further investigation and model verification. The importance of determining the particle concentration profile within μ-capillaries is explicitly demonstrated as shear induced migration causes significant concentration gradients to occur at strong flow conditions (i.e. Pe p ¼270).

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“…Most of these techniques struggle to be quantitatively applied to the opaque, complex water in crude oil emulsions considered here. Microscopy and light scattering techniques, for example, are either destructive or invasive; light scattering can only be applied to dilute emulsions; and confocal microscopy needs the addition of fluorescent contrast agents to one of the emulsion phases. ,− NMR pulsed field gradient (PFG) techniques generate the DSD of emulsions based on the measurement of the restricted self-diffusion of molecules within the boundaries of the droplet phase; these do not require dilution and are effectively non-invasive . They can be readily applied to concentrated, opaque, or complex emulsions , as is the case in the work presented here.…”

Section: Introductionmentioning

confidence: 99%

Oil-Based Binding Resins: Peculiar Water-in-Oil Emulsion Breakers

et al. 2019

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Asphaltenes are widely associated with the unwanted stability of water-in-crude oil (w/o) emulsions due to their inhibitory effect on water droplet coalescence. Here, we seek to prove that certain crude oil resins that can bind with asphaltenes, hereafter referred to as binding resins, are capable of solvating these asphaltenes such that the w/o emulsion destabilizes. W/o emulsions were formed using a variety of crude oils as well as model oils with varying amounts of resins and asphaltenes. A modified SARA fractionation technique was adopted to extract the required resins and asphaltenes. Emulsion stability was tracked over time both visually and via the use of pulsed field gradient nuclear magnetic resonance to quantify the emulsions’ water droplet size distributions. It was conclusively found that the binding resins significantly improved the demulsification rate of the emulsions formed using both crude oil and model oils. In the case of the model oils, this influence could only be attributed to the removal of the asphaltenes from the droplet surfaces by the binding resins; the effect was shown to be partially independent of the source of the binding resin. The use of this oil fraction subclass for emulsion destabilization shows great promise as a new flow assurance strategy by substituting costly synthetic chemical emulsion destabilizers with naturally occurring resins.

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Anomalous preasymptotic colloid transport by hydrodynamic dispersion in microfluidic capillary flow

Cited by 13 publications

References 36 publications

Limits to flow detection in phase contrast MRI

Limits to flow detection in phase contrast MRI

Colloid particle transport in a microcapillary: NMR study of particle and suspending fluid dynamics

Oil-Based Binding Resins: Peculiar Water-in-Oil Emulsion Breakers

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