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11.
Numerical simulations have been performed for flow past two equal‐sized square cylinders in tandem arrangement subjected to incoming planar shear flow. Effect of L/d ratio and the shear parameter has been studied. The range of L/d ratio (ratio of center‐to‐center distance (L) to cylinder width (d)) is varied from 2 to 7 and the non‐dimensional shear parameter (K) is varied from 0.0 to 0.4 in steps of 0.1. For all the cases the Reynolds number (Re) based on centerline velocity and cylinder width is fixed at 100. The results are compared with that of isolated square cylinder with uniform flow. Strouhal number decreases with increasing shear parameter. There are more than one shedding frequency at high shear parameters and L/d ratios. The mean drag coefficient is decreased with shear parameter and lesser than that of the single cylinder. The root mean square (RMS) value of both lift and drag coefficients is higher for the downstream cylinder for all values of shear parameter. With increasing L/d ratio, for both lift and drag, the RMS value increases and then decreases for upstream cylinder, whereas it continuously increases for the downstream cylinder. The stagnation point is moved towards the top leading edge with increasing shear. The critical L/d ratio, which is defined as the distance between two cylinders, beyond which the vortex shedding from the upstream cylinder occurs, decreases with increasing shear parameter. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
12.
Interactive vortex shedding in the multiply connected domain formed by a pair of circular cylinders is analysed by the FEM–FDM blending technique. The vorticity–streamfunction formulation is used to solve the incompressible Navier–Stokes equations at Re = 100, with the time-dependent wall streamfunctions determined from the pressure constraint condition and the far-field streamfunctions from the integral series formula developed earlier by the authors. The standard Galerkin finite element method is used in the relatively small FEM subdomain and the finite difference method based on the general co-ordinate system in the rest of the flow domain. Symmetric, antisymmetric and asymmetric wake patterns are obtained confirming the earlier experimental findings. The bistable nature of the asymmetric vortex shedding as well as the intermittent drifting from one status to the other between symmetric and antisymmetric wake patterns are reported. 相似文献
13.
M. Rahman 《Applied Mathematical Modelling》1986,10(6):401-408
This paper considers the wave loads on large monolithic offshore structures. The second order wave force formulae developed by Rahman and Heaps, applicable to large circular cylinders in waves, are extended to evaluate the overturning moments on large circular cylinders. The theory is then applied to square section caissons in waves, to predict the wave loads on these structures. These calculations are performed using the exact form of the second order velocity potential, φ2, with arbitrary wave number, k2, and the approximate form of φ2, with twice the value of the wave number of the first order velocity potential. The second order analytical predictions are compared with available experimental data for various ranges of wave parameters for both circular and square caissons in large amplitude waves. 相似文献
14.
Jinying XuXiangdong Zhang 《Physics letters. A》2011,375(13):1524-1527
We present a rigorous multiple-scattering method to calculate the interaction energies due to electromagnetic field fluctuations in a cluster of parallel cylinders. Various kinds of cluster structure with both isotropic and anisotropic materials are considered. It is shown that Casimir interactions are sensitive to the positions of the cylinders in the cluster or the structure of the system. The sign of the interaction energy cannot only be changed by tuning the parameters of anisotropic materials, it can also be caused by changing the cylinders configuration of the system. 相似文献
15.
In this study, we have developed a new numerical approach to solve differential-type viscoelastic fluid models for a commonly used benchmark problem, namely, the steady Taylor—Couette flow between eccentric cylinders. The proposed numerical approach is special in that the nonlinear system of discretized algebraic flow equations is solved iteratively using a Newton–Krylov method along with an inverse-based incomplete lower-upper preconditioner. The numerical approach has been validated by solving the benchmark problem for the upper-convected Maxwell model at a large Deborah number. Excellent agreement with the numerical data reported in the literature has been found. In addition, a parameter study was performed for an extended White–Metzner model. A large eccentricity ratio was chosen for the cylinder system in order to allow flow recirculation to occur. We detected several interesting phenomena caused by the large eccentricity ratio of the cylinder system and by the viscoelastic nature of the fluid. Encouraged by the results of this study, we intend to investigate other polymeric fluids having a more complex microstructure in an eccentric annular flow field. 相似文献
16.
We consider the conduction of heat or electricity between a pair of equal, touching cylinders embedded in a matrix. We solve exactly a problem in which each cylinder contains a heat source, and analyse the solution asymptotically for the case in which the conductivity of the fibres is much greater than that of the matrix. Using this analysis, we assess the accuracy of approximate schemes for calculating the interactions between the fibres of a composite material. We conclude that the approximate solutions are better at predicting global quantities, such as total flux, than they are at predicting pointwise quantities such as the temperature field. 相似文献
17.
An approach developed earlier to solve two-dimensional static problems for noncircular cylindrical shells is used to analyze the effect of the spatial frequency and amplitude of corrugation on the stress–strain state of shells. The results of the analysis are presented in the form of plots and tables 相似文献
18.
本文研究了一端弹性支撑的并列双柱和串列双圆柱在气流中自由端的振幅响应,与单圆柱相比,在小间距时,串列双圆柱中前柱的横向振幅受到较强的激励。而在大间距时,振幅受到抑制,特别当L/D=3.5和4.0时,其振幅响应仅为单柱的1/3左右,而对于后柱,则在大间距时,纵向振幅响应有所增大,而且后柱的振幅响应要比前柱的大得多,而并列双圆柱的自由端振幅基本上受到抑制,在T/D>3.0之后,干扰很快减小到接近单个圆 相似文献
19.
20.
The purpose of this research is to investigate the effects of material inhomogeneity on the response of linearly elastic isotropic solid circular disks or cylinders, rotating at constant angular velocity about
a central axis. The work is motivated by the recent research activity on functionally graded materials (FGMs), i.e., materials
with spatially varying properties tailored to satisfy particular engineering applications. The analog of the classic problem
for a homogeneous isotropic rotating solid disk or cylinder is considered. The special case of a body with Young"s modulus depending on the
radial coordinate only, and with constant Poisson"s ratio, is examined. For the case when the Young"s modulus has a power-law
dependence on the radial coordinate, explicit exact solutions are obtained. It is shown that the stress response of the inhomogeneous disk (or cylinder) is significantly different from that of the homogeneous body. For example, the maximum radial and hoop
stresses do not, in general, occur at the center as in the case for the homogeneous material. Furthermore, for the case where the Young"s
modulus increases with radial distance from the center, it is shown that radially symmetric solutions exist provided the rate of growth of
the Young"s modulus is, at most, cubic in the radial variable. It is also shown for the general inhomogeneous isotropic case how the material inhomogeneity may
be tailored so that the radial and hoop stress are identical throughout the disk.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献