Use of trajectory analysis to study stability of colloidal dispersions in flow fields

Zeichner, G. R.; Schowalter, W. R.

doi:10.1002/aic.690230306

Cited by 202 publications

(182 citation statements)

References 24 publications

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“…In fact, because interparticle forces are so important in flocculation processes, stability results similar to those displayed in Fig. 3 are also found in shear-induced flocculation (5,7). That is, lyophobic colloids can be unstable at low and high shear rates, but stable against shear-induced flocculation at intermediate rates.…”

Section: (G(r) }supporting

confidence: 66%

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Gravity-induced flocculation

Melik

Fogler

1984

Journal of Colloid and Interface Science

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In polydisperse colloidal systems, flocculation can occur as a result of the differential creaming rates between small and large particles. As an improvement on earlier work, we have rigorously modelled this process of gravity-induced flocculation by incorporating gravitational and interparticle (both attractive and repulsive) forces, as well as hydrodynamic interactions in our analysis. From this analysis capture cross-sections and collision frequencies can be precisely defined and computed. In the absence of electrostatic repulsion, the gravity-induced flocculation rate is approximately proportional to gO.8O (where g is the local acceleration of gravity) and not g as previously predicted. When electrostatic repulsion is significant, particles can flocculate into either a primary or secondary minimum (as described by DLVO theory), or remain dispersed. The possibility of two different types of doublets leads to an interesting phenomenon. When Brownian motion can be neglected, dilute spherical sols can be unstable at low and high gravitational forces, but stable against gravity-induced flocculation at intermediate values.

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Section: (G(r) }supporting

confidence: 66%

“…[1][2][3][4][5][6][7][8][9][10], there has been no analogous study of particle/particle aggregation due to sedimentation (gravity-induced) flocculation in polydisperse colloidal systems. Gravity-induced flocculation arises from the differential creaming rates between large and small particles.…”

Section: Introductionmentioning

confidence: 99%

Gravity-induced flocculation

Melik

Fogler

1984

Journal of Colloid and Interface Science

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“…characterizing aerosol stability as a function of flow type, have been carried out previously in the context of steady laminar flows (Zeichner & Schowalter 1977;Feke & Schowalter 1983), laminar chaotic flows (Bidkar & Khakhar 1990) and for a homogeneous stationary isotropic turbulence flow field (Brunk, Koch & Lion 1998). It has been found in these calculations that the neglect of hydrodynamic interactions usually leads to significant over-predictions of coagulation efficiency (Brunk et al 1998).…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Trajectory analysis for non-Brownian inertial suspensions in simple shear flow

Subramanian

Brady

2006

J. Fluid Mech.

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We analyse pair trajectories of equal-sized spherical particles in simple shear flow for small but finite Stokes numbers. The Stokes number, St =γ τ p , is a dimensionless measure of particle inertia; here, τ p is the inertial relaxation time of an individual particle andγ is the shear rate. In the limit of weak particle inertia, a regular small-St expansion of the particle velocity is used in the equations of motion to obtain trajectory equations to the desired order in St. and St 1/3 φ 1, respectively. Further, the region of zero-Stokes closed trajectories is destroyed, and there exists a new attracting limit cycle whose location in the shearing plane is, at leading order, independent of St. The extension of the present analysis to include a generic linear flow, and the implications of the finite-St trajectory modifications for coagulating systems are discussed.

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“…On the other hand, JV^remains constant since it is independent of external force, as seen in Eq. (13). For interpretation of the results in the stability plane, consider a situation in which doublets are present in a suspension for NR= 104 as in Fig.…”

Section: Stability Of Colloidal Particlesmentioning

confidence: 99%

Collision efficiency and colloidal stability of unequal size spherical particles moving through quiescent viscous liquid.

Yuu

Nakagawa

Mihara

et al. 1987

J. Chem. Eng. Japan

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Collision efficiencies have been computed for unequal-size spherical particles settling in quiescent viscous liquids, taking into account the hydrodynamic interaction, interparticle attraction and electrostatic repulsion. The results are closely related to the mechanism of coagulation of colloidal particles in a sedimentation field. If the interparticle attraction and electrostatic repulsion are both negligibly small as comparedto viscous drag, the collision efficiency r\ is very small, i.e. about 0.003. However, a relatively large Van der Waals force makes tj greater than unity. As the ratio of the radii of the two particles (smaller divided by larger) decreases the collision efficiency also decreases. The repulsive force between particles determines whether the collision efficiency is zero or larger than zero, but it does not affect the magnitude of the collision efficiency. By including the effect of electrostatic repulsion wewere able to develop criteria which determine the stability (or flocculation) of colloidal particles.

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Use of trajectory analysis to study stability of colloidal dispersions in flow fields

Cited by 202 publications

References 24 publications

Gravity-induced flocculation

Gravity-induced flocculation

Trajectory analysis for non-Brownian inertial suspensions in simple shear flow

Collision efficiency and colloidal stability of unequal size spherical particles moving through quiescent viscous liquid.

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