Spreading and fingering in a yield-stress fluid during spin coating

Holloway, Kristi E.; Tabuteau, Hervé; Bruyn, John R. de

doi:10.1007/s00397-009-0409-1

Cited by 8 publications

(5 citation statements)

References 29 publications

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“…The fluid used in this experimental study is a solution of polymer micro-gel Carbopol at a 0.1 wt% concentration. In the literature, this material has been widely used as a model viscoplastic fluid in standard rheological measurements [23,24], channel configurations [16,25,26], drag force studies [27,28], and more complex hydrodynamics such as gravity-driven free-surface flows [29][30][31], fingering instabilities [32,33] and drop impacts [34,35]. The choice for this yield-stress fluid is often related to its ease of preparation and to the stability of its rheological properties over time (i.e.…”

Section: A Model Yield-stress Fluidmentioning

confidence: 99%

Experimental study of the solid-liquid interface in a yield-stress fluid flow upstream of a step

Luu¹,

Philippe²,

Chambon

2015

Phys. Rev. E

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We present an experimental study investigating the transition zone between a liquid-like unyielded region and a solid-like yielded region in a yield-stress fluid. The configuration consists of a rectangular closed-channel flow disturbed by the presence of a step. Upstream of the step, a solid-liquid interface between a dead zone and a flow zone appears. In this study, we use a model fluid, namely polymer micro-gel Carbopol, which exhibits Herschel-Bulkley viscoplastic rheology. Exploiting the fluid transparency, the flow is monitored by particle image velocimetry using an internal visualization technique. The main outcome of this study is to show that, except in a thin transition layer close to the solid-liquid interface, the flow behaves as an apparent Poiseuille flow with an apparent slip condition at the base. The slip frontier is found to be almost independent of the flow rate while the corresponding slip velocity increases with the flow rate.

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Section: A Model Yield-stress Fluidmentioning

confidence: 99%

Experimental study of the solid-liquid interface in a yield-stress fluid flow upstream of a step

Luu¹,

Philippe²,

Chambon

2015

Phys. Rev. E

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“…These may be caused by Marangoni instabilities or fluid mechanical instabilities (83,88), or by gas phase influences (89).…”

Section: Spin Coatingmentioning

confidence: 99%

Coating Processes

Cohen¹,

Lightfoot²

2011

Kirk-Othmer Encyclopedia of Chemical Technology

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Coating process technology is in widespread use because the surface of most materials needs to be treated in order for the final product to meet all the functional needs and requirements. The modification is accomplished by applying a coating or series of coatings to the material to improve its performance and make it more suitable for use, or to give it different characteristics. Many of the commercially available coating applicators are described, including units for simultaneous multilayer application, for discrete coating, and for patch coating. While convection drying is emphasized, brief descriptions of conduction and infrared heating, as well as of UV and electron‐beam curing, are given.

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“…[1][2][3][4][5][6][7][8] The presence of particles in such a spreading thin film of liquid (i.e., a suspension or a slurry) is encountered in different applications [9][10][11] and can exhibit several complexities during spreading and ensuing fingering patterns. [12][13][14] For suspensions which exhibit yield stress behavior, the capillary ridge gets stabilized by the innate yield strength of the fluid allowing the film to spread to a larger area before the instability ensues. 12,15 Linear stability analysis of the thin film equations for such yield stress fluids, incorporating a suitable stress constitutive equation, correctly predicts the observed behavior.…”

Section: Introductionmentioning

confidence: 99%

“…12,15 Linear stability analysis of the thin film equations for such yield stress fluids, incorporating a suitable stress constitutive equation, correctly predicts the observed behavior. 15 In certain cases, however, the instability can be simply due to local yielding of the suspension 14 and not the usual contact line instability along the advancing film front. An enhancement in the fingering instability, compared to the base suspending liquid, is predicted using linear stability analysis of thin film equations for hard sphere, non-Brownian, well-mixed suspensions.…”

Section: Introductionmentioning

confidence: 99%

Fingering instability of a suspension film spreading on a spinning disk

et al. 2016

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The spreading of a thin film of suspension on a spinning disk and the accompanying contact line instability is studied through flow visualization experiments. The critical radius for the onset of instability shows an increase with increase in the particle fraction ($\phi_{p}$) before decreasing slightly at the highest value of $\phi_{p}$ studied, while the instability wavelength ($\lambda$) exhibits a non-monotonic dependence. The value of $\lambda$ is close to that for a partially wetting liquid at lower $\phi_{p}$, it decreases with increasing $\phi_{p}$ to a minimum before increasing again at largest $\phi_{p}$. The non-monotonic trends observed for $\lambda$ are discussed in light of the linear stability analysis of thin film equations derived for suspensions by Cook {\it et al.} [Linear stability of particle-laden thin films, Eur. Phys. J.: Spec. Top. {\bf 166}, 77 (2009)] and Balmforth {\it et al.} [Surface tension driven fingering of a viscoplastic film, J. Non Newtonian Fluid Mech. {\bf 142}, 143 (2007)].Comment: 8 pages, 6 figure

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Spreading and fingering in a yield-stress fluid during spin coating

Cited by 8 publications

References 29 publications

Experimental study of the solid-liquid interface in a yield-stress fluid flow upstream of a step

Experimental study of the solid-liquid interface in a yield-stress fluid flow upstream of a step

Coating Processes

Fingering instability of a suspension film spreading on a spinning disk

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