Slot coating of time-dependent structured materials: Effects of thixotropy on the flow dynamics and operating limits

IF 2.7 2区工程技术 Q2 MECHANICS

Journal of Non-Newtonian Fluid Mechanics Pub Date : 2024-10-22 DOI:10.1016/j.jnnfm.2024.105344

C. Sanchez-Perez, D. Maza, I.R. Siqueira, P.R. de Souza Mendes, M.S. Carvalho

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引用次数: 0

Abstract

Some of the most common liquid-like formulations rooted in the coating industry consist of rheologically complex structured materials such as inks, paints, and slurries. Yet, the impact of time-dependent structuring effects due to thixotropy on thin film coating applications remains elusive and still unclear. Here, we present a computational study of the effects of thixotropy on slot coating of time-dependent structured materials. By coupling a recent fluidity-based constitutive model for thixotropic materials with a well-established finite element/elliptic mesh generation method for free surface flows, we assess the role of thixotropy by comparing the predictions from the thixotropic model with those from a simple Generalized Newtonian Fluid model that uses the same flow curve for the material steady-state equilibrium viscosity. We find that thixotropy can indeed have a major impact on slot coating applications, potentially bringing strong implications not only to the flow dynamics but also to the operating limits of the process. In conclusion, the results and discussions we present in this study underscore the importance of accounting for thixotropy to genuinely model and fundamentally understand the behavior of time-dependent structured materials with complex rheology in processing flows like those ubiquitous across the broad fields of coating science and engineering.

查看原文本刊更多论文

随时间变化的结构材料槽涂层：触变性对流动动力学和工作极限的影响

涂料工业中最常见的一些液态配方由流变学结构复杂的材料组成，如油墨、油漆和泥浆。然而，由触变性引起的随时间变化的结构效应对薄膜涂层应用的影响仍然难以捉摸，尚不清楚。在此，我们介绍了触变性对随时间变化的结构材料的槽涂层影响的计算研究。通过将最新的基于流体力学的触变性材料构成模型与成熟的自由表面流有限元/椭圆网格生成方法相结合，我们比较了触变性模型与简单的广义牛顿流体模型的预测结果，评估了触变性的作用，后者使用相同的流动曲线来计算材料的稳态平衡粘度。我们发现，触变性确实会对槽涂层应用产生重大影响，不仅会对流动动力学产生重大影响，还会对工艺的操作极限产生重大影响。总之，我们在本研究中介绍的结果和讨论强调了考虑触变性对真正建模和从根本上理解具有复杂流变性的随时间变化的结构材料在加工流中的行为的重要性，这些材料在涂层科学和工程的广泛领域中无处不在。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Journal of Non-Newtonian Fluid Mechanics 物理-力学

CiteScore

5.00

自引率

19.40%

发文量

109

审稿时长

61 days

期刊介绍： The Journal of Non-Newtonian Fluid Mechanics publishes research on flowing soft matter systems. Submissions in all areas of flowing complex fluids are welcomed, including polymer melts and solutions, suspensions, colloids, surfactant solutions, biological fluids, gels, liquid crystals and granular materials. Flow problems relevant to microfluidics, lab-on-a-chip, nanofluidics, biological flows, geophysical flows, industrial processes and other applications are of interest. Subjects considered suitable for the journal include the following (not necessarily in order of importance): Theoretical, computational and experimental studies of naturally or technologically relevant flow problems where the non-Newtonian nature of the fluid is important in determining the character of the flow. We seek in particular studies that lend mechanistic insight into flow behavior in complex fluids or highlight flow phenomena unique to complex fluids. Examples include Instabilities, unsteady and turbulent or chaotic flow characteristics in non-Newtonian fluids, Multiphase flows involving complex fluids, Problems involving transport phenomena such as heat and mass transfer and mixing, to the extent that the non-Newtonian flow behavior is central to the transport phenomena, Novel flow situations that suggest the need for further theoretical study, Practical situations of flow that are in need of systematic theoretical and experimental research. Such issues and developments commonly arise, for example, in the polymer processing, petroleum, pharmaceutical, biomedical and consumer product industries.