Measuring Advection and Diffusion of Colloids in Shear Flow

Duits, Michael H.G.; Ghosh, Somnath; Mugele, Friedrich Gunther

doi:10.1021/acs.langmuir.5b01369

Cited by 18 publications

(15 citation statements)

References 49 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In dilute suspensions ( = 0.03), both D x and D y are practically equal to each other and almost independent of the overall flow rate and the y location (data shown elsewhere [46]) Exceptions to this are only found in close proximity of the walls due to the (anisotropic) hydrodynamic resistance close to the wall. As the particles are only weakly interacting with each other in dilute suspensions, their diffusive behavior should be similar to that of a solitary particle at rest as well as in flow.…”

Section: Influence Of Shearmentioning

confidence: 83%

“…To measure the velocity profile we extended publicly available particle tracking codes [56,57] to allow accurate measurement of diffusive motions that are superimposed onto a flow [46]. Briefly, the flow velocity v x (y) is first measured by dividing the Y range into bins and averaging intrabin displacements over (many) frames.…”

Section: Discussionmentioning

confidence: 99%

“…We measure the diffusive behaviors by applying particle tracking on data that are collected with a confocal scanning laser microscope. Although this method requires great care to ensure that the advective displacements are adequately removed before the diffusive ones are analyzed [46], it offers two key advantages: (i) The measurements are directional, i.e., both flow and shear directions are examined, and (ii) the measurements are spatially resolved, i.e., a distinction is made between the different flow lanes. This makes the method particularly well suited for the study of micron-sized spheres under (nearly) refractive index matched conditions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effects of shear and walls on the diffusion of colloids in microchannels

2015

Self Cite

View full text Add to dashboard Cite

Colloidal suspensions flowing through microchannels were studied for the effects of both the shear flow and the proximity of walls on the particles' self-diffusion. Use of hydrostatic pressure to pump micron-sized silica spheres dispersed in water-glycerol mixture through poly(dimethylsiloxane) channels with a cross section of 30×24μm(2), allowed variation in the local Peclet number (Pe) from 0.01 to 50. To obtain the diffusion coefficients, image-time series from a confocal scanning laser microscope were analyzed with a method that, after finding particle trajectories, subtracts the instantaneous advective displacements and subsequently measures the slopes of the mean squared displacement in the flow (x) and shear (y) directions. For dilute suspensions, the thus obtained diffusion coefficients (D(x) and D(y)) are close to the free diffusion coefficient at all shear rates. In concentrated suspensions, a clear increase with the Peclet number (for Pe > 10) is found, that is stronger for D(x) than for D(y). This effect of shear-induced collisions is counteracted by the contribution of walls, which cause a strong local reduction in D(x) and D(y).

show abstract

Section: Influence Of Shearmentioning

confidence: 83%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effects of shear and walls on the diffusion of colloids in microchannels

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…As is well-known in the literature, it is possible to map dimer models and the six-vertex models onto height models, and to make the connection with bosonic free field theory, also called gaussian free field in the mathematical literature (see e.g. [60,61,62,63,64]). In the physics literature, such methods are often called Coulomb gas methods (see Ref.…”

Section: Height Mapping and The Gaussian Free Fieldmentioning

confidence: 99%

Inhomogeneous field theory inside the arctic circle

Allegra¹,

Dubail²,

Stéphan³

et al. 2016

J. Stat. Mech.

123

252

View full text Add to dashboard Cite

Abstract. Motivated by quantum quenches in spin chains, a one-dimensional toy-model of fermionic particles evolving in imaginary-time from a domain-wall initial state is solved. The main interest of this toymodel is that it exhibits the arctic circle phenomenon, namely a spatial phase separation between a critically fluctuating region and a frozen region. Large-scale correlations inside the critical region are expressed in terms of correlators in a (euclidean) two-dimensional massless Dirac field theory. It is observed that this theory is inhomogenous: the metric is position-dependent, so it is in fact a Dirac theory in curved space. The technique used to solve the toy-model is then extended to deal with the transfer matrices of other models: dimers on the honeycomb and square lattice, and the six-vertex model at the free fermion point (∆ = 0). In all cases, explicit expressions are given for the long-range correlations in the critical region, as well as for the underlying Dirac action. Although the setup developed here is heavily based on fermionic observables, the results can be translated into the language of height configurations and of the gaussian free field, via bosonization. Correlations close to the phase boundary and the generic appearance of Airy processes in all these models are also briefly revisited in the appendix.

show abstract

“…The structures of various systems, such as colloidal suspensions including electrorheological fluids, [1][2][3] magnetorheological suspensions, [4][5][6][7] ferrofluids, [8][9][10][11] living cells suspensions, [12] and so on, are very sensitive to the change of interparticle forces. Unfortunately, some shearing flow that is inevitable in experiments and natural environments can cause the rotation of the colloidal particles, [13][14][15][16][17][18][19][20][21][22][23] thus reducing the interparticle force to some extent. An interaction between a rotating electric field and suspended particles or cells can also lead to a rotational motion of the particles.…”

Section: Introductionmentioning

confidence: 99%

Alternating-current relaxation of a rotating metallic particle

et al. 2016

View full text Add to dashboard Cite

Based on a first-principles approach, we establish an alternating-current (AC) relaxation theory for a rotating metallic particle with complex dielectric constant ε α =ε α − iσ α /ω 0 . Hereε α is the real part,σ α the conductivity, ω 0 the angular frequency of an AC electric field, and i = √ −1. Our theory yields an accurate interparticle force, which is in good agreement with the existing experiment. The agreement helps to show that the relaxations of two kinds of charges, namely, surface polarized charges (described byε α ) and free charges (corresponding toσ α ), contribute to the unusually large reduction in the attracting interparticle force. This theory can be adopted to determine the relaxation time of dynamic particles in various fields.

show abstract

Measuring Advection and Diffusion of Colloids in Shear Flow

Abstract: Analysis of the dynamics of colloids in shear flow

Cited by 18 publications

References 49 publications

Effects of shear and walls on the diffusion of colloids in microchannels

Effects of shear and walls on the diffusion of colloids in microchannels

Inhomogeneous field theory inside the arctic circle

Alternating-current relaxation of a rotating metallic particle

Contact Info

Product

Resources

About