On the CFD Analysis of a Stratified Taylor-Couette System Dedicated to the Fabrication of Nanosensors

Abstract

Abstract:Since the pioneering work of Taylor, the analysis of flow regimes of incompressible, viscous fluids contained in circular Couette systems with independently rotating cylinders have charmed many researchers. The characteristics of such kind of flows have been considered for some industrial applications. Recently, Taylor-Couette flows found an innovative application in the production of optical fiber nanotips, to be used in molecular biology and medical diagnostic fields. Starting from the activity of Barucci et al., the present work concerns the numerical analysis of a Taylor-Couette system composed by two coaxial counter-rotating cylinders with low aspect ratio and radius ratio, filled with three stratified fluids. An accurate analysis of the flow regimes is performed, considering both the variation of inner and outer rotational speed and the reduction of fiber radius due to etching process. The large variety of individuated flow configurations provides useful information about the possible use of the Taylor-Couette system in a wide range of engineering applications. For the present case, the final objective is to provide accurate information to manufacturers of fiber nanotips about the expected flow regimes, thus helping them in the setup of the control process that will be used to generate high-quality products.

Fiber-Optic Nanosensors for Chemical Detection

“…Using different dynamic regimes of rotation during this process, it is possible to vary the cone angle, the shape, and the roughness of the nanotips. Hydrodynamic flows during the process are analyzed theoretically [50].…”

“…Moreover, multiple tapered tips can be prepared using different dynamic regimes [46]. There is another variant of the dynamic etching method that employs the independent rotations of a container with an etchant, protective solvent, and etched fiber [49,50]. Both the container and fiber rotate around the same axis.…”

Several different ways to increase the accuracy of the numerical solution of the first order wave equation

“…The movement of gas in a wind tunnel, the propagation of tsunami waves, the spread of plasma in a trap, weather changes and other numerous phenomena in science and technology are described by various mathematical models represented as integral or partial differential equations. Modern computational algorithms make it possible to solve these systems of equations with sufficient accuracy in two-dimensional and three-dimensional approximations when solving various classes of problems [1][2], considering real geometries and non-stationarity of the process [3]. Further progress in the development of numerical methods is associated with the development of new numerical algorithms and an increase in the speed and power of modern computer technology [1], [4][5][6][7][8].…”

Experimental insights into elasto-inertial transitions in Taylor–Couette flows

“…Taylor–Couette (TC) flow, the flow between two concentric cylinders, has received considerable fundamental and practical interest over the last 100 years. It has served as a common rheological flow and a paradigm to study hydrodynamic instabilities since the work of [ 1 ]—due to its apparent geometrical simplicity—and enjoys numerous applications in manufacturing and process engineering: bioreactors for cell cultivation and tissue engineering [ 2 – 4 ], nanosensor fabrication [ 5 ], water purification [ 6 ], graphite exfoliation into graphene [ 7 ], starch hydrolysis [ 8 , 9 ], shearing of proteins [ 10 , 11 ] to name but a few.…”