Forces on Cylinders and Spheres in a Sinusoidally Oscillating Fluid

1975 ◽  
Vol 42 (1) ◽  
pp. 32-37 ◽  
Author(s):  
T. Sarpkaya
Keyword(s):  
Fourier Analysis ◽  
Reynolds Numbers ◽  
Transverse Force ◽  
Circular Cylinders ◽  
Driving Frequency ◽  
Line Force ◽  
Cylinders And Spheres

The in-line and transverse forces acting on circular cylinders and the in-line force acting on spheres immersed in a harmonically oscillating fluid in a U-shaped vertical tunnel have been measured. The drag, inertia, and the transverse force (lift) coefficients have been determined through the use of a Fourier analysis and found to depend on a period parameter. The results have shown that the transverse force on cylinders is as large as the in-line force and alternates at frequencies ranging from one to four times the driving frequency of the fluid within the range of subcritical Reynolds numbers encountered in the investigation.

Forces on Cylinders Near a Plane Boundary in a Sinusoidally Oscillating Fluid

1976 ◽  
Vol 98 (3) ◽  
pp. 499-503 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Reynolds Number ◽  
Least Squares ◽  
Least Squares Method ◽  
Lift Coefficient ◽  
Transverse Force ◽  
Circular Cylinders ◽  
Plane Boundary ◽  
Water Tunnel ◽  
Inertia Coefficient ◽  
Line Force

The in-line and transverse forces acting on circular cylinders placed near a plane boundary in a sinusoidally oscillating fluid in a U-shaped vertical water tunnel have been measured. The period parameter UmT/D was varied from about 2 to 40, the Reynolds number from 4000 to 25,000, and the gap between the cylinder and the plane boundary from 0.01 D to 1.0D. The drag and inertia coefficients for the in-line force have been determined through the use of the Morison’s equation and the Fourier analysis, least squares method, and a modified least squares method. The transverse force coefficients have been obtained for the forces toward the wall and away from the wall. The results show that the in-line and transverse forces could acquire very large magnitudes and give rise to serious oscillations. For very small values of the period parameter, effects of flow separation become negligible and the inertia coefficient for the in-line force and the lift coefficient for the transverse force approach those predicted by the potential theory.

scholarly journals FORCES ON ROUGH-WALLED CIRCULAR CYLINDERS

1976 ◽  
Vol 1 (15) ◽  
pp. 134 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Vortex Shedding ◽  
Oscillatory Flow ◽  
Least Squares Method ◽  
Reynolds Numbers ◽  
Transverse Force ◽  
Circular Cylinders ◽  
Mean Square ◽  
Relative Roughness

This paper presents the results of an extensive experimental investigation of the in-line and transverse forces acting on sand-roughened circular cylinders placed in oscillatory flow at Reynolds numbers up to 1,500,000, Keulegan-Carpenter numbers up to 100, and relative roughnesses from 1/800 to 1/50. The drag and inertia coefficients have been determined through the use of the Fourier analysis and the least squares method. The transverse force (lift) has been analysed in terms of its maximum and root-mean-square values. In addition, the frequency of vortex shedding and the Strouhal number have been determined. The results have shown that all of the coefficients cited above are functions of the Reynolds number, Keulegan-Carpenter number, and the relative roughness height. The results have also shown that the effect of roughness is quite profound and that the drag coefficients obtained from tests in steady flow are not applicable to harmonic flows even when the loading is predominantly drag.

In-Line and Transverse Forces on Cylinders in Oscillatory Flow at High Reynolds Numbers

1977 ◽  
Vol 21 (04) ◽  
pp. 200-216 ◽  
Author(s):  
Turgut Sarpkaya
Keyword(s):  
Oscillatory Flow ◽  
Least Squares Method ◽  
Reynolds Numbers ◽  
Transverse Force ◽  
Circular Cylinders ◽  
Relative Roughness ◽  
High Reynolds Numbers ◽  
Smooth Cylinder ◽  
New Interpretation ◽  
High Reynolds

This paper presents the results of an extensive experimental investigation of the in-line and transverse forces acting on smooth and sand roughened circular cylinders placed in oscillatory flow at Reynolds numbers up to 1.5 × 106, Keulegan Carpenter numbers up to 100, and relative roughnesses from 1/800 to 1/50. The drag and inertia coefficients have been determined through the use of the Fourier analysis and the least-squares method. The transverse force (lift) has been analyzed in terms of its maximum, semi peak-to-peak, and root-mean-squarevalues. In addition, the frequency of vortex shedding and the Strouhal number have been determined. The results have shown that (a) for smooth cylinders, all of the coefficients just cited are functions of the Reynolds and Keulegan-Carpenter numbers, particularly for Reynolds numbers larger than about 20 000; (b) for rough cylinders, the force coefficients also depend on the relative roughness k/D and differ significantly from corresponding to the smooth cylinder; and that (c) the use of the frequencyparameter' D2/vT and the roughness Reynolds number Umk/vallows a new interpretation of the present as well as the previously obtained data.

scholarly journals Aerodynamics of smooth and rough square-section prisms at incidence in very high Reynolds-number cross-flows

2021 ◽  
Vol 62 (3) ◽  
Author(s):  
Nils Paul van Hinsberg
Keyword(s):  
Reynolds Number ◽  
Cross Sections ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Surface Boundary ◽  
Experimental Proof ◽  
Surface Boundary Layer ◽  
Pitch Moment ◽  
The Mean ◽  
High Reynolds

Abstract The aerodynamics of smooth and slightly rough prisms with square cross-sections and sharp edges is investigated through wind tunnel experiments. Mean and fluctuating forces, the mean pitch moment, Strouhal numbers, the mean surface pressures and the mean wake profiles in the mid-span cross-section of the prism are recorded simultaneously for Reynolds numbers between 1$$\times$$ × 10$$^{5}$$ 5 $$\le$$ ≤ Re$$_{D}$$ D $$\le$$ ≤ 1$$\times$$ × 10$$^{7}$$ 7 . For the smooth prism with $$k_s$$ k s /D = 4$$\times$$ × 10$$^{-5}$$ - 5 , tests were performed at three angles of incidence, i.e. $$\alpha$$ α = 0$$^{\circ }$$ ∘ , −22.5$$^{\circ }$$ ∘ and −45$$^{\circ }$$ ∘ , whereas only both “symmetric” angles were studied for its slightly rough counterpart with $$k_s$$ k s /D = 1$$\times$$ × 10$$^{-3}$$ - 3 . First-time experimental proof is given that, within the accuracy of the data, no significant variation with Reynolds number occurs for all mean and fluctuating aerodynamic coefficients of smooth square prisms up to Reynolds numbers as high as $$\mathcal {O}$$ O (10$$^{7}$$ 7 ). This Reynolds-number independent behaviour applies to the Strouhal number and the wake profile as well. In contrast to what is known from square prisms with rounded edges and circular cylinders, an increase in surface roughness height by a factor 25 on the current sharp-edged square prism does not lead to any notable effects on the surface boundary layer and thus on the prism’s aerodynamics. For both prisms, distinct changes in the aerostatics between the various angles of incidence are seen to take place though. Graphic abstract

scholarly journals On the Scope of Lagrangian Vortex Methods for Two-Dimensional Flow Simulations and the POD Technique Application for Data Storing and Analyzing

Entropy ◽  
2021 ◽  
Vol 23 (1) ◽  
pp. 118
Author(s):  
Kseniia Kuzmina ◽  
Ilia Marchevsky ◽  
Irina Soldatova ◽  
Yulia Izmailova
Keyword(s):  
Flow Simulation ◽  
Internal Flow ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Vortex Methods ◽  
Flow Simulations ◽  
Additional Information ◽  
Two Dimensional Flow ◽  
Different Shapes ◽  
Problem Formulations

The possibilities of applying the pure Lagrangian vortex methods of computational fluid dynamics to viscous incompressible flow simulations are considered in relation to various problem formulations. The modification of vortex methods—the Viscous Vortex Domain method—is used which is implemented in the VM2D code developed by the authors. Problems of flow simulation around airfoils with different shapes at various Reynolds numbers are considered: the Blasius problem, the flow around circular cylinders at different Reynolds numbers, the flow around a wing airfoil at the Reynolds numbers 104 and 105, the flow around two closely spaced circular cylinders and the flow around rectangular airfoils with a different chord to the thickness ratio. In addition, the problem of the internal flow modeling in the channel with a backward-facing step is considered. To store the results of the calculations, the POD technique is used, which, in addition, allows one to investigate the structure of the flow and obtain some additional information about the properties of flow regimes.

Numerical Simulation for Flow over Two Circular Cylinders in Micro Channel with Lattice Boltzmann Method

2014 ◽  
Vol 670-671 ◽  
pp. 747-750
Author(s):  
Zhi Jun Gong ◽  
Jiao Yang ◽  
Wen Fei Wu
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Recirculation Zone ◽  
Flow Characteristics ◽  
Reynolds Numbers ◽  
Circular Cylinders ◽  
Micro Channel ◽  
Zone Length ◽  
Spacing Ratio ◽  
Boltzmann Method

For indepth study on flow characteristics for fluid bypass obstacles in micro-channel, the Lattice Boltzmann Method (LBM) was used to simulate fluid flow over two circular cylinders in side-by-side arrangement of a micro-channel. The velocity distribution and recirculation zone length under different Reynolds numbers (Re = 0~100) and different spacing ratio (H/D= 0~2.0) were obtained. The results show that the pattern of flow and the size of recirculation zone in the micro-channel depend on the combined effect of Re and H/D.

Extra Drag Force on a Circular Cylinder Due to the Presence of Solid Particles in Subsonic Compressible Flow

1991 ◽  
Author(s):  
Stanley B. Mellsen
Keyword(s):  
Compressible Flow ◽  
Incompressible Flow ◽  
Aerodynamic Drag ◽  
Collection Efficiency ◽  
Reynolds Numbers ◽  
Solid Particles ◽  
Circular Cylinders ◽  
Critical Mach Number ◽  
Wide Range ◽  
Inertia Parameters

Abstract The effect of particles, such as dust in air on aerodynamic drag of circular cylinders was calculated for compressible flow at critical Mach number and for incompressible flow. The effect of compressibility was found negligible for particles larger than about 10 μm, for which the air can be considered a continuum. Drag coefficient and collection efficiency are provided for a wide range of inertia parameters and Reynolds numbers for both compressible and incompressible flow.

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