Circular Cylinder Of Finite Length Research Articles

Drag of finite length circular cylinder in low Reynolds number region. Effect of plane side-walls.

The falling drag test of circular cylinders was carried out in a low Reynolds number region in order to study the effects of cylinder length and plane side-walls on the drag of cylinders. From the data analysis based on the dimensional analysis method, it is shown that the drag coefficient of finite length circular cylinders is expressed by an empirical formula composed of the Tachibana-Iemoto expression in two dimensional theory and the correlation function of three variables (L/D, H/D and B/H). In the useful region of our formula, the drag of cylinders increases with an increase of the ratio of length to diameter (L/D) and a decrease of plane side-wall variables (H/D and B/H).

Mobility of a Small Sphere in a Viscous Fluid Confined in a Rigid Circular Cylinder of Finite Length

A theoretical study is made on the effect of finiteness of the length of a circular cylinder on the translational motion of a small sphere along its centerline. Fluid occupying that region is assumed viscous and incompressible, and the analysis is based on the Stokes equations. The method of reflections is employed and first-order correction of the force experienced by the sphere is obtained. For longer cylinders, end-effects on the force are important only when the sphere is very close to the endwalls, while for cylinders whose length is the same order of magnitude as its radius, end-and sidewalls play equally significant roles. Among cylindrical boxes containing the same amount of fluid volume, additional resistance force at the center becomes minimum for a cylinder with its length/diameter ratio of about 0.56. Streamlines are also shown.

Numerical solution for the flow of viscoelastic fluids around an inclined circular cylinder.

Finite difference solutions have been obtained by the perturbation method to investigate the influence of shear thinning and elasticity on the flow around an inclined circular cylinder of finite length in a uniform flow. In this numerical analysis a generalized upper-convected Maxwell model, in which the viscosity changes according to the Cross model, has been used.

Application of a variational principle to acoustic radiation from a vibrating finite cylinder

A variational principle derived from the Kirchhoff‐Helmholtz integral corollary is applied to a rigid cylinder; previous applications have been to acoustic radiation and diffraction from an infinitely thin disk [J. H. Ginsberg et al., J. Acoust. Soc. Am. Suppl. 1 77, S60 (1985)]. For a finite length circular cylinder, additional complications are encountered because of the need to consider the cylindrical sides as well as ends. The basis functions for a Rayleigh‐Ritz solution have different analytical forms on the sides and ends, although they must be continuous at the edges. A larger number of functions are required to get a good representation of the surface pressure. Calculation of the resulting matrix elements for the determination of the expansion coefficients is nontrivial because of the logrithmic singularities presented by the Green's function integrals. The surface pressure is expected to be finite, but the tangential derivative of the surface pressure is a priori known to have a s−2/3 singularity at the edges separating the side wall and ends. It is not necessary that trial functions exhibit the latter behavior, but if they are so chosen, a good convengence is expected for a smaller number of basis functions. A numerical method based on splitting each integrand into a simple singularity term plus a nonsimple but bounded term is described. Numerical results are compared with those obtained by an alternative technique developed by P. H. Rogers [NRL Report 7240 (19 June 1972)].

Complex acoustic and electromagnetic resonance frequencies of prolate spheroids and related elongated objects and their physical interpretation

A numerical calculation of the complex eigenfrequencies of prolate spheroids and ellipsoids, and of finite-length circular cylinders undergoing acoustic or electromagnetic eigenvibrations is reported. While mainly longitudinal eigenvibrations have been studied previously, here we obtained eigenfrequencies of vibrations which contain azimuthal components. These give rise (e.g., for the case of a cylinder) to helical surface waves, and we were able to interpret the corresponding eigenfrequencies in terms of resonances caused by the phase matching of such surface waves as they repeatedly engulf, and propagate around, the vibrating object. Phase and group velocities and absorption coefficients of the surface waves are obtained numerically from the set of complex eigenfrequencies.

Transient Thermal Stress Problem in a Transversely Isotropic Finite Length Circular Cylinder Due to an Asymmetric Heating

Transient Thermal Stress Problem in a Transversely Isotropic Finite Length Circular Cylinder Due to an Asymmetric Heating

Flow Past Circular Cylinder of Finite Length Placed Normal to Ground Plane in Uniform Shear Flow

Flow Past Circular Cylinder of Finite Length Placed Normal to Ground Plane in Uniform Shear Flow

Scattering from wires and open circular cylinders of finite length using entire domain Galerkin expansions

Electromagnetic (EM) scattering by finite-length, perfectly conducting open cylinders (i.e., ducts or tubes) with circular cross sections is considered. The case of a straight wire, viewed as a thin cylinder, is examined in this context. The salient features of this study are a) use of the electric field integral equation (EFIE) as a starting point, b) solution of this equation by the Galerkin method, and c) representation of the axial variation of the currents on the scatterer by an entire domain (Fourier series) expansion. Edge modes are considered in the expansion set and their effect is examined. The open cylinder backscatter cross section is computed as a function of aspect angle for various radii and lengths and is compared with measured data.

Radiation configuration factors for obliquely oriented finite length circular cylinders

Radiation configuration factors for obliquely oriented finite length circular cylinders

The Drag Force for a Circular Cylinder of Finite Length in Dilute Polymer Solutions

ニュートン流体中および希薄高分子溶液中において無限長円柱および有限長円柱の抵抗を調べた. 直径と長さの比(e/d)の異なる数種類の円柱を用いて1<Re<5×104で抵抗を, 1.7×104<Re<5×104で円柱まわりの圧力分布を測定した. その結果次のことがらが明らかになった. (1)抵抗はe/dの増加に伴ってRe<20では減少し, Re>20では増加する. (2)希薄高分子溶液中ではニュートン流体中よりもRe>1×103で抵抗が大きく減少する.

Scattering of a plane electromagnetic wave by a conducting circular cylinder of finite length

AbstractThis paper presents an exact solution for scattering of a plane EM move (TM mode) by a perfect conducting circular hollow cylinder having no end caps. The scattered field is evaluated in the Fourier domain using the Wiener‐Hopf technique. The scattered field is divided into the IPO (improved physical optics) field, TE and TM modes in the cylinder and the diffracted fields at two edges. The range of the scattering angle where the IPO field gives good approximation is almost independent of the cylinder length if the cylinder length is larger than several wavelengths.

Transient Thermal Stress Problems in a Finite Length Circular Cylinder under a Nonuniform Heat Supply

Transient Thermal Stress Problems in a Finite Length Circular Cylinder under a Nonuniform Heat Supply

Free vibration of circular cylinders of variable thickness

Flexural vibrations of finite length circular cylinders with shear diaphragm ends and symmetric circumferential wall thickness variations are described by using the Rayleigh-Ritz method. Both symmetric and asymmetric solutions are presented. Only circumferential variations in the wall radial dimension are considered; the method is amenable, however, to consideration of longitudinal variations in wall thickness as well. The cylinder wall thickness variation is described as a Fourier series and the vibration is described as a series of modes of a uniform cylinder with the same mean radius. The theory has been applied to a cylinder whose inner bore is circular but is non-concentric with the circular outer surface. The mode shapes have been investigated experimentally by using time-averaged holograms of the vibrating cylinder and the results compare well with the predictions of the theory. The frequencies of the modes agree with the theoretical predictions to within 2%.

Unsteady fluid dynamic forces on a simply-supported circular cylinder of finite length conveying a flow, with applications to stability analysis

An exact analytic expression for the unsteady fluid pressure acting on the internal walls of a simply-supported circular cylindrical tube of finite length, carrying flow, is presented. The generalized force coefficients corresponding to specific modes of deformation are given explicitly. The results are applied to two problems: (1) the interaction of flow and buckling of thin-walled cylindrical shells subjected to lateral pressure and/or end thrust; (2) the aeroelastic stability of the shells. The second problem is aimed at resolving some controversy about post-divergence flutter oscillation of cylindrical shells or plates exposed to a subsonic flow. The shell equation, of the Morley type, is solved by Galerkin's method and an analytic approach is used to examine the stability of the system. It is important that damping be taken into account in the analysis. The undeformed configuration is always unstable when the flow speed exceeds the minimum divergence boundary.

A Numerical Investigation of the Efficiency with which Simple Columnar Ice Crystals Collide with Supercooled Water Drops

Abstract The Navier-Stokes equation of motion for two-dimensional, viscous, steady-state incompressible flow past an infinitely long circular cylinder was solved by numerical techniques for Reynolds numbers between 0.1 and 50. From the streamfunction and vorticity fields the pressure at the cylinder surface, the pressure drag, and the frictional drag were computed, and from the latter two the total drag on the cylinder was derived. The values found for the drag compared well with the best theoretical and experimental values reported in literature, suggesting that our flow fields were sufficiently accurate. These flow fields were used to determine the hydrodynamic interaction between simple columnar ice crystals idealized as circular cylinders of finite length L′, of radius aL′, and of Reynolds number NRe,L (67.1≤L′≤2440 µm; 23.5≤ aL′≤146.4 µm;0.2≤NRe,L <20) and spherical water drops of radius aS′ varying between 2 and 134µm. The flow fields used to describe the flow past drops were numerically computed by...

Natural frequencies of free finite-length circular cylinders

Sets of tables are given for the natural frequencies of the first five symmetric and first five antisymmetric modes of a hollow or solid cylinder for circumferential wave numbers n = 0, 1, 2. Contour graphs are given for the lowest frequencies as functions of (length)/(mean radius) and (thickness)/(mean radius).

Neumann Functions for Laplace's Equation for a Circular Cylinder of Finite Length

In this paper general solutions for the Neumann problem for a circular cylinder of finite length are presented in terms of re-defined Neumann functions. The Neumann function, which has a zero normal derivative on the boundary, does not exist in a finite region according to Gauss's theorem. However, there exists a potential function due to a unit source which has a non-zero normal derivative. This function is defined as the Neumann function in the finite region. The Neumann functions for a circular cylinder of finite length are presented in three different forms. They correspond to three types of expressions of the potential function, called z-, r-, and ϕ-forms after Dougall's work. These Neumann functions play the same role in the Neumann type boundary value problem as Green's function in the Dirichlet type problem. The different forms are useful because they have their own regions of rapid convergence.

Radial–Axial Transient Heat Conduction in a Region Bounded Internally by a Circular Cylinder of Finite Length and Appreciable Heat Capacity

The problem of two-dimensional transient heat conduction from a circular cylinder of finite length and appreciable heat capacity has been solved using a Laplace transformation with respect to time and a finite Fourier sine transformation with respect to the axial variable. A case of constant surface heat flux with the ends of the cylinder maintained at zero temperature is considered. The solution, valid for all values of time, is compared with that of Jaeger for the infinitely long cylinder. The results are of use in the evaluation of heat losses for the transient hot-wire method of determining the thermal conductivity of fluids.

The Experimental Investigation on the Flow Past a Circular Cylinder of Finite Length Placed Normal to the Plane Surface in a Uniform Stream

The Experimental Investigation on the Flow Past a Circular Cylinder of Finite Length Placed Normal to the Plane Surface in a Uniform Stream

Flow patterns in models of small airway units of the lung

Quasi-steady creeping flow in models of small airway units of the lung is investigated. A respiratory unit of the lung is modelled by a sphere, an oblate and a prolate ellipsoid of revolution, and a circular cylinder of finite length. The solution of the Stokes equations for each of these geometries is indicated for general axi-symmetric boundary conditions. For particular cases consistent with the models, streamlines are plotted and some velocity profiles are shown. It is suggested that bulk 00w in the ha1 generations of the lung is significant for gas transport even though diffusion is the predominant mechanism there.