The turbulent flow of mildly elastic drag reducing fluids through a straight tube rotating around an axis perpendicular to
its own is analysed using boundary layer approximations. The momentum integral approach is used and the governing equations
have been solved numerically using the Runge-Kutta-Merson method. The influence of the Deborah number on the velocity distribution
and the boundary layer thickness has been exemplified through the analysis.
NCL Communication No. 3354. 相似文献
Conjugated polymers may be induced by intra‐ and/or intermolecular non‐covalent forces to fold into helical conformations. Helices formed by aromatic amide, hydrazide, and urea polymers possess a well‐organized cavity and depth, which is defined by their degree of polymerization. Driving forces may be intramolecular hydrogen bonding and/or solvophobicity, or guest induction. The resulting long helices represent a new class of unimacromolecular dynamic tubular architectures that exhibit unique properties or functions in, for example, molecular recognition, chirality transfer, and ion transporting. The recent advances are highlighted here.
The problem of axisymmetric wave flow of a viscous incompressible fluid in a system consisting of a long thin deformable tube and a terminal element that determines the conditions of wave reflection at the tube end is analyzed. An expression for the input admittance of the system is obtained and the dependence of the admittance on the system parameters is investigated. The resonant frequencies at which the admittance amplitude has extrema are found and it is shown that at these frequencies the admittance variations with variation of the terminal-element parameters are maximal. The dependence of the resonant frequency on the tube length is investigated. Possible applications of the results obtained to the hydromechanical interpretation of a novel method of pulse diagnostics are discussed. 相似文献
The present work is a study of the gas-flow phenomenon known as the “end of the vortex” (EoV), which spontaneously occurs at the lower end, or under, reverse-flow centrifugal separators such as cyclones or swirl tubes. Different CFD models of swirl tubes have been built to study and analyse this phenomenon in detail. The present numerical work is based on—and compared with—previous experimental observations of this phenomenon. The numerical models were built in complete agreement with the geometrical configurations and operating conditions used in these earlier experimental studies [1]. Two different configurations of swirl tubes were analyzed. One configuration was an in principle long tube with variable length in which the dependence on the vessel length of the behaviour of the vortex core in a simple, well-defined geometry was studied. The other configuration was equipped with a wide “dust collection vessel” at the bottom, the depth of which was varied, to study the behaviour of the vortex core in a widely-used geometry. 3-D LES simulations were carried out using the commercial CFD package Star-CD. The bending of the vortex core to the wall of the vessel and its precessional motion, constituting the phenomenon of the EoV, was seen in both configurations, and the obtained results are in very good agreement, both qualitatively and to an extent quantitatively, with previous experimental results [1]. 相似文献