02139nas a2200157   4500008004100000022001400041245007800055210006900133260008700202300002700289490000700316520152700323100001701850700001801867856009601885       2016                        eng d  a1070-663100aFingering instability in the flow of a power-law fluid on a rotating disc0 aFingering instability in the flow of a powerlaw fluid on a rotat  a1305 WALT WHITMAN RD, STE 300, MELVILLE, NY 11747-4501 USAbAMER INST PHYSICScJAN  aArticle Number: 0131020 v283 a<p>A computational study of the flow of a non-Newtonian power law fluid on a spinning disc is considered here. The main goal of this work is to examine the effect of non-Newtonian nature of the fluid on the flow development and associated contact line instability. The governing mass and momentum balance equations are simplified using the lubrication theory. The resulting model equation is a fourth order non-linear PDE which describes the spatial and temporal evolutions of film thickness. The movement of the contact line is modeled using a constant angle slip model. To solve this moving boundary problem, a numerical method is developed using a Galerkin/finite element method based approach. The numerical results show that the spreading rate of the fluid strongly depends on power law exponent n. It increases with the increase in the shear thinning character of the fluid (n &lt; 1) and decreases with the increase in shear thickening nature of the fluid (n &gt; 1). It is also observed that the capillary ridge becomes sharper with the value of n. In order to examine the stability of these ridges, a linear stability theory is also developed for these power law fluids. The dispersion relationship depicting the growth rate for a given wave number has been reported and compared for different power-law fluids. It is found that the growth rate of the instability decreases as the fluid becomes more shear thinning in nature, whereas it increases for more shear thickening fluids. (C) 2016 AIP Publishing LLC.</p>1 aArora, Akash1 aDoshi, Pankaj  uhttps://library.ncl.res.in/content/fingering-instability-flow-power-law-fluid-rotating-disc02834nas a2200241   4500008004100000022001400041245007600055210006900131260010600200300001200306490000800318520195600326653002202282653002602304653002402330653002602354653001902380653002702399100002602426700001702452700001802469856010502487       2016                        eng d  a0045-793000aTwo-layer spin coating flow of newtonian liquids: a computational study0 aTwolayer spin coating flow of newtonian liquids a computational   aTHE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD OX5 1GB, ENGLANDbPERGAMON-ELSEVIER SCIENCE LTDcJUN  a180-1890 v1313 a<p>Spin coating is the most commonly used method in industries to form coating films of desired thickness and functionality. In case of two-layer spin coating process, stratified layers of two immiscible liquids are deposited onto the substrate simultaneously, which spread and thin to form two-layer coating film of finite thickness. Questions concerning the effect of surface/interfacial tension on uniformity of these films and contact line evolution are relevant and need thorough investigation. Therefore, an axisymmetric model governing the flow of two-layer spin coating process is developed here. Liquids used for the study are assumed to be Newtonian and fully wetting. The contact line singularity is resolved using a precursor layer model and the governing equations are simplified using lubrication approximation. A Galerkin finite-element method (G/FEM) based scheme is developed to solve the resulting fourth order non-linear PDEs. Simulation results reveal that the fluid properties like ratio of the viscosity of upper layer fluid to lower layer and ratio of the upper gas-liquid surface tension to inner liquid-liquid interfacial tension have profound impact on the time evolution of the film profile, contact radius and shape of the capillary ridges. It is observed that a uniform two-layer film surrounded by thin single layer film is formed when the viscosity ratio is small. On the contrary, when viscosity ratio is large, a thin two-layer film surrounded by bulky capillary ridges is formed. Similarly, the results also show that sharpness of capillary ridge increases with decrease in the surface tension ratio. Further, it is found that increase in the precursor layer thickness increases the spreading rate, thereby making the film more uniform. Finally, the uniformity of the final two-layer film does not get affected by the initial volume of fluid present in the upper layer. (C) 2016 Elsevier Ltd. All rights reserved.</p>10aAxisymmetric flow10aMathematical modeling10aMulti-layer coating10aPrecursor layer model10aThin-film flow10aTwo-layer spin coating1 aSahoo, Subhadarshinee1 aArora, Akash1 aDoshi, Pankaj  uhttps://library.ncl.res.in/content/two-layer-spin-coating-flow-newtonian-liquids-computational-study