Asymptotic and numerical analysis of a simple model for blade coating

Motivated by the industrial process of blade coating, the two-dimensional flow of a thin film of Newtonian fluid on a horizontal substrate moving parallel to itself with constant speed under a fixed blade of finite length in which the flows upstream and downstream of the blade are coupled via the flow under the blade is analysed. A combination of asymptotic and numerical methods is used to investigate the number and nature of the steady solutions that exist. Specially, it is found that in the presence of gravity there is always at least one, and (depending on the parameter values) possibly as many as three, steady solutions, and that when multiple solutions occur they are identical under and downstream of the blade, but differ upstream of it. The stability of these solutions is investigated, and their asymptotic behaviour in the limits of large and small flux and weak and strong gravity effects, respectively, determined

A creative destruction approach to replication: implicit work and sex morality across cultures

How can we maximize what is learned from a replication study? In the creative destruction approach to replication, the original hypothesis is compared not only to the null hypothesis, but also to predictions derived from multiple alternative theoretical accounts of the phenomenon. To this end, new populations and measures are included in the design in addition to the original ones, to help determine which theory best accounts for the results across multiple key outcomes and contexts. The present pre-registered empirical project compared the Implicit Puritanism account of intuitive work and sex morality to theories positing regional, religious, and social class differences; explicit rather than implicit cultural differences in values; self-expression vs. survival values as a key cultural fault line; the general moralization of work; and false positive effects. Contradicting Implicit Puritanism's core theoretical claim of a distinct American work morality, a number of targeted findings replicated across multiple comparison cultures, whereas several failed to replicate in all samples and were identified as likely false positives. No support emerged for theories predicting regional variability and specific individual-differences moderators (religious affiliation, religiosity, and education level). Overall, the results provide evidence that work is intuitively moralized across cultures

Marangoni driven structures in thin film flows

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Streamlets and branching dynamics in surfactant driven flow

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Generation of high-resolution surface temperature distributions

We have performed numerical calculations to study the generation of arbitrary temperature profiles with high spatial resolution on the surface of a solid. The characteristics of steady-state distributions and time-dependent heating and cooling cycles are examined, as well as their dependence on material properties and device geometry. Ideally, low-power consumption and fast response times are desirable. The simulations show that the achievable spatial resolution is on the order of the substrate thickness and that the response time t1 depends on the width of the individual heating elements. Moreover, the rise time t1 can be significantly shortened by deposition of a thermal insulation layer, which also reduces the power consumption and increases lateral resolution

Physical mechanisms governing pattern fidelity in microscale offset printing

We have studied the offset printing of liquid polymers curable by exposure to ultraviolet light onto flat and unpatterned silicon and glass substrates. The interplay of capillary, viscous, and adhesion forces dominates the dynamics of ink transfer at small feature sizes and low capillary number. For smooth and nonporous substrates, pattern fidelity can be compromised because the ink contact lines are free to migrate across the substrate during plate separation. Using a combination of experiments and equilibrium simulations, we have identified the physical mechanisms controlling ink transfer and pattern fidelity. In considering the resolution limit of this technique, it appears that the dynamics of ink flow and redistribution during transfer do not explicitly depend on the absolute feature size, but only on the aspect ratio of film thickness to feature size. Direct printing holds promise as a high-throughput fabrication method for large area electronics

Shallow flows of generalised Newtonian fluids on an inclined plane

We derive a general evolution equation for a shallow layer of a generalised Newtonian fluid undergoing two-dimensional gravity-driven flow on an inclined plane. The flux term appearing in this equation is expressed in terms of an integral involving the prescribed constitutive relation and, crucially, does not require explicit knowledge of the velocity profile of the flow; this allows the equation to be formulated for any generalised Newtonian fluid. In particular, we develop general solutions for travelling waves on a mild slope and for kinematic waves on a moderately steep slope; these results provide simple and accessible models of, for example, the propagation of non-Newtonian mud and debris flows