A computational study of the effect of particle migration on the low-flow limit in slot coating of particle suspensions

Siqueira, Ivan R.; Carvalho, Márcio S.

doi:10.1007/s11998-019-00196-4

Cited by 14 publications

(9 citation statements)

References 28 publications

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“…There exists no velocity gradient in the plug flow zone 3. Meanwhile, despite the circulation, the fluid moving toward the upstream (zone 1) is limited 41,43 ; hence, the effect of particle agglomeration on the entire coating process is little. Most of the dispersions move to the right side of the feeding slot (zone 2) where the nonuniform shear flow has a strong impact on the particle distribution and aggregation in the resulting film 40 .…”

Section: Theoretical Analysismentioning

confidence: 99%

“…In the particulate coating processes, shear-driven particle migration is the dominant mechanism of particle transport and the leading cause of particle nonuniform distribution and agglomeration. 2,[40][41][42][43][44] In other words, the ink dispersion (i.e., flow effect) is determined by the coating flow structure, especially the shear rate distributions. This lays a foundation for the particulate coating window.…”

Section: Theoretical Analysismentioning

confidence: 99%

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Slot die coating window for a uniform fuel cell ink dispersion

Pan

Chen

et al. 2022

AIChE Journal

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The continuous roll‐to‐roll slot die coating technique has shown great potential for fuel cell electrode fabrication. It is essential to determine the particulate coating window to obtain a defect‐free film of uniform thickness and uniform particle dispersion. For this dual‐purpose, an additional upper operating limit has been proposed via a “flow field analysis scheme” that combines analysis and simulation. In this analysis, the fundamentals of flow pattern transition (Poiseuille–Couette–bubbly flow) behind coating limits are clarified. The Couette flow is advantageous for uniform shear rate and dispersion. Furthermore, phase‐field simulations systematically investigate the effect of fluid and geometrical parameters and quantitatively present the flow limit with explicit expression. Results reveal that the slope of the upper limit is inversely correlated with shear‐thinning index n while proportional to the coating gap H. Combining the bubble entrainment boundary, lower n and H are favorable for a larger particulate coating window.

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Section: Theoretical Analysismentioning

confidence: 99%

Section: Theoretical Analysismentioning

confidence: 99%

Slot die coating window for a uniform fuel cell ink dispersion

Pan

Chen

et al. 2022

AIChE Journal

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“…The method has been successfully used to study different free surface flows of Newtonian liquids, 9,17-21 viscoelastic polymer solutions, [22][23][24][25][26] and particle suspensions. [27][28][29][30][31] We present a brief review of the overall numerical scheme in this section. The interested reader can find more details elsewhere (e.g., see Pasquali 32 and the references therein).…”

Section: Finite Element Formulationmentioning

confidence: 99%

“…The computational method used in this work is based on a mixed finite element formulation for free surface flows. The method has been successfully used to study different free surface flows of Newtonian liquids, 9,17–21 viscoelastic polymer solutions, 22–26 and particle suspensions 27–31 . We present a brief review of the overall numerical scheme in this section.…”

Section: Mathematical Modelingmentioning

confidence: 99%

Computational study of planar extrudate swell flows with a viscous liquid–gas interface

et al. 2021

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We present a computational study of planar extrudate swell flows of Newtonian liquids with a viscous liquid-gas interface. The model consists of the equations of motion coupled with the Boussinesq-Scriven constitutive equation for the interfacial stress tensor. The resulting set of equations is solved with the finite element method coupled with an elliptic mesh generation strategy to capture the free surface. The results show a detailed parametric study in terms of the capillary number and the Boussinesq number, a dimensionless parameter used to measure the ratio of viscous forces at the interface to viscous forces in the bulk liquid. The predictions reveal that the extrudate swells dramatically as the interfacial viscosity grows. The interfacial viscosity slows down the flow both in the bulk liquid and at the interface, and thus the extrudate size increases to conserve mass in the slow plug flow that develops under the free surface.

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“…Based on Fluent software, Lee et al [8,9] studied the flow characteristics of Newtonian and non-Newtonian coatings in the process of slotted coating, providing a basis for the optimization design of slotted coating moulds. A fully coupled model proposed by Siqueira et al [10,11] was applied to the slotted coating flow. The slotted coating flow of slender particle suspension was analysed and the particle concentration and average orientation in the coating were studied.…”

Section: Introductionmentioning

confidence: 99%

Modelling and Simulation of Transverse Homogeneity of Slotted Coating Process

Wang¹,

Zhong²,

Li³

et al. 2022

J. Phys.: Conf. Ser.

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Slot coating is a kind of precise coating process, which is widely used in the production of membrane materials. The thickness deviation of coating along the transverse direction is the key index to measure the coating quality. The homogeneity of the transverse distribution of the coating velocity at the exit of the die is the most direct factor leading to the transverse thickness deviation of the coating. To predict the transverse homogeneity of slot coating, a mathematical model for the internal flow field in the die was established, where the incompressible Navier-Stokes equations were used to describe the fluid flow and generalized Newtonian fluid model was used to describe the rheological behaviour of non-Newtonian coating. An efficient explicit splitting algorithm based on finite element method is proposed to solve the model. To verify the effectiveness of the model and the algorithm, the internal flow field of a trapezoidal double cavity die with equal section was simulated. The transverse homogeneity obtained was close to the experimental measured value, which verified the validity of the model. Furthermore, the influence of measuring slot width on the transverse homogeneity of outlet velocity is studied, and the simulation results are consistent with the theoretical expectations.

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A computational study of the effect of particle migration on the low-flow limit in slot coating of particle suspensions

Cited by 14 publications

References 28 publications

Slot die coating window for a uniform fuel cell ink dispersion

Slot die coating window for a uniform fuel cell ink dispersion

Computational study of planar extrudate swell flows with a viscous liquid–gas interface

Modelling and Simulation of Transverse Homogeneity of Slotted Coating Process

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