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We present a numerical study on vortex-induced vibration (VIV) of a freely vibrating two degree-of-freedom circular cylinder in close proximity to a stationary plane wall. Fully implicit combined field scheme based on Petrov–Galerkin formulation has been employed to analyze the nonlinear effects of wall proximity on the vibrational amplitudes and hydrodynamic forces. Two-dimensional simulations are performed as a function of decreasing gap to cylinder diameter ratio for reduced velocities at ReD=100 and ReL=2900, where ReD and ReL denote the Reynolds numbers based on the cylinder diameter and the upstream distance, respectively. We investigate the origin of enhanced streamwise oscillation of freely vibrating near-wall cylinder as compared to the isolated cylinder counterpart. For that purpose, detailed analysis of the amplitudes, frequency characteristics and the phase relations has been performed for the isolated and near-wall configurations. Initial and lower branches in the amplitude response are found from the gap ratios of 0.75 to 10, similar in nature to the isolated cylinder laminar VIV. A third response branch has been found between the initial and the lower branch at the gap ratio of . For near-wall cases, phase relation between drag force and streamwise displacement varies from close to 0° to 180°. Between , the effect of wall proximity on the frequency response tends to disappear. The effect of mass-ratio is further investigated. Finally, we introduce new correlations for characterizing peak amplitudes and forces as a function of the gap ratio for a cylinder vibrating in the vicinity of a stationary plane wall. 相似文献
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É. N. Bereslavskii 《Journal of Applied Mechanics and Technical Physics》1989,30(5):755-758
Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 88–91, September–October, 1989. 相似文献
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A. Ya. Oleinik 《Fluid Dynamics》1967,2(5):97-100
Water filtration to partially penetrating wells in a uniform confined stratum has been extensively studied recently. Considerably less study has been made of filtration to partially penetrating wells in layered strata, which are frequently encountered in practice. Some particular cases of this problem were considered in [1–4], and its most complete solution was given in [4]. However, this solution is presented in a general form which is difficult to apply in practice.In the following we present the solution of the water filtration problem to partially penetrating wells in a two-layer confined stratum for the cases of the operating portion of the well located in both the upper and lower stratum layers. The problem is solved by the method developed in [5, 6], where the potential of a point sink is first found, and then the potential of a line sink of intensity q is found, which is then used as the operating portion of the well.Applying to the resulting solutions the known method of filtration resistances, approximate relations are presented for the final calculations. 相似文献
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Martien A. Hulsen 《Theoretical and Computational Fluid Dynamics》1993,5(1):33-48
A numerical method is used to study the influence of inertia and elongational properties on the vortex growth in the flow of a viscoelastic fluid through a four-to-one contraction. It appears that the vortex growth regime and the divergent flow regime, which are observed in experiments for some fluids, can be found for a choice of the material parameters where both the elongational stresses and the inertia forces are large for the flow rate considered. After studying the type and the vorticity it is concluded that the appearance of a divergent flow regime is likely to be a critical phenomenon (i.e., a change of type for a critical velocity) and that large elongational stresses are essential as well. 相似文献
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Matthew R. Begley 《Journal of the mechanics and physics of solids》2004,52(9):2005-2023
We present theoretical and experimental results to describe the mechanics of indentation of a clamped circular membrane with a frictionless spherical indenter. Analytical expressions and numerical simulations are presented for the relationships between contact radius, finite indentation strains (and stresses), pre-stretch, loads and deflection. These closed-form solutions are contrasted with point-load models that neglect the contact size (i.e. classical Schwerin-type solutions), and lead to important differences in the indentation strain and load-deflection response. The accuracy of these closed form expressions is illustrated by comparisons with detailed numerical results and experiments on thin elastomer films. We show that the closed-form solutions can be used to extract mechanical properties from indentation testing of freestanding films, with important implications for developing new tests on nanoscale films and/or compliant materials such as polymers and biological substances. 相似文献
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Vlasios Leontidis Jie Chen Lucien Baldas Stéphane Colin 《Heat and Mass Transfer》2014,50(8):1065-1080
A numerical procedure has been developed for modeling 2D thermal creep flows with Fluent®. Complete first order velocity slip, including thermal creep and walls curvature effects, as well as temperature jump, boundary conditions, are implemented via C routines. After validation on benchmark flows, the technique is used for designing a Knudsen pump with curved microchannels and it is demonstrated that this micropump can be efficient in the slip flow regime. 相似文献
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V. I. Zalkind V. V. Kirillov Yu. A. Larionov N. S. Semenov 《Journal of Applied Mechanics and Technical Physics》1970,11(1):131-135
The preliminary results of an investigation of the operation of MHD generator electrodes at relatively high current densities are reported. The experiments were conducted in the channel of a MHD generator, driven by combustion products, with both cooled metal and silicon carbide electrodes. Observation and photographs of the electrodes revealed that at sufficiently high currents microarcs appear at the electrode surface. The phenomenological aspects of arc behavior under conditions characteristic of MHD generator operation are examined. The electrode-insulator interface has an important influence on arc behavior, as does the film of potassium compounds deposited on the electrode surface. These characteristics of the microarcs may be of considerable significance in relation to electrode erosion processes.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, Vol. 11, No. 1, pp. 130–134, January–February, 1970. 相似文献
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An immersed interface method for flow past circular cylinder in the vicinity of a plane moving wall 下载免费PDF全文
Two‐dimensional flows past a stationary circular cylinder near a plane boundary are numerically simulated using an immersed interface method with second‐order accuracy. Instead of a fixed wall, a moving wall with no‐slip boundary is considered to avoid the complex involvement of the boundary layer and to focus only on the shear‐free wall proximity effects for investigating the force dynamics and flow fields. To analyze the convergence and accuracy of our implementation, numerical studies have been first performed on a simple test problem of rotational flow, where the second order of convergence is confirmed through numerical experiments and an optimal range of relative grid‐match ratio of Lagrangian to Eulerian grid sizes has been recommended. By comparing the force quantities and the Strouhal number, the accuracy of this method has been demonstrated on the flow past a stationary isolated cylinder. The cylinder is then put in proximity to the wall to investigate the shear‐free wall proximity effects in the low Reynolds number regime (20≤Re≤200). The gap ratio, e/D, where e denotes the gap between the cylinder and the moving wall and D denotes the diameter of the cylinder, is taken from 0.10 to 2.00 to determine the critical gap ratio, (e/D)critical, for the alternate vortex shedding, where the fluid forces, flow fields and the streamwise velocity profiles are studied. One of the key findings is that the (e/D)critical for the alternate vortex shedding decreases as the Reynolds number increases. We also find that, in this low Reynolds number regime, the mean drag coefficient increases and peaks at e/D = 0.5 with the increase of e/D and keeps decreasing gently from e/D = 0.5 to e/D = 2.0, while the mean lift coefficient decreases monotonically with the increase of e/D. New correlations are then proposed for computing force coefficients as a function of Re and e/D for a cylinder in the vicinity of a moving plane wall. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献