Some experimental results on sphere and disk drag

Roos, Frederick W.; Willmarth, William W.

doi:10.2514/3.6164

Cited by 282 publications

(150 citation statements)

References 18 publications

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“…As one could expect, the wake structure is exactly that of the flow past a fixed disk, once the uniform flow at infinity has been removed. The drag coefficient C D ≃ 1.20 compares well with the value C D ≃ 1.23 determined experimentally by Roos & Willmarth (1971); the recirculation length, l R , obtained by determining the point of the symmetry axis where V x = −1, is l R ≃ 2.2, in good agreement with the value l R ≃ 2.1 obtained numerically for Re = 116.9 by Meliga, Chomaz & Sipp (2009a).…”

Section: Base Flowsupporting

confidence: 87%

Global linear stability analysis of the wake and path of buoyancy-driven disks and thin cylinders

2014

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OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 11158 The stability of the vertical path of a gravity-or buoyancy-driven disk of arbitrary thickness falling or rising in a viscous fluid, recently studied through direct numerical simulation by Auguste, Magnaudet & Fabre (J. Fluid Mech., vol. 719, 2013, pp. 388-405), is investigated numerically in the framework of global linear stability. The disk is allowed to translate and rotate arbitrarily and the stability analysis is carried out on the fully coupled system obtained by linearizing the Navier-Stokes equations for the fluid and Newton's equations for the body. Three disks with different diameter-to-thickness ratios are considered: one is assumed to be infinitely thin, the other two are selected as archetypes of thin and thick cylindrical bodies, respectively. The analysis spans the whole range of body-to-fluid inertia ratios and considers Reynolds numbers (based on the fall/rise velocity and body diameter) up to 350. It reveals that four unstable modes with an azimuthal wavenumber m = ±1 exist in each case. Three of these modes result from a Hopf bifurcation while the fourth is associated with a stationary bifurcation. Varying the body-to-fluid inertia ratio yields rich and complex stability diagrams with several branch crossings resulting in frequency jumps; destabilization/restabilization sequences are also found to take place in some subdomains. The spatial structure of the unstable modes is also examined. Analyzing differences between their real and imaginary parts (which virtually correspond to two different instants of time in the dynamics of a given mode) allows us to assess qualitatively the strength of the mutual coupling between the body and fluid. Qualitative and quantitative differences between present predictions and known results for wake instability past a fixed disk enlighten the fact that the first non-vertical regimes generally result from an intrinsic coupling between the body and fluid and not merely from the instability of the sole wake.

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Section: Base Flowsupporting

confidence: 87%

Global linear stability analysis of the wake and path of buoyancy-driven disks and thin cylinders

2014

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“…Since the flow is steady and symmetric in this range, a 2D, steady-state, axisymmetric model could effectively capture the flow structure. Furthermore, the experimental drag data taken in the steady flow field was more reliable than measurements taken during vortex shedding at higher Reynolds numbers [24]. Additionally, the drag coefficient correlation used for comparison was valid for incompressible flows (at low Mach numbers), which required low velocities (and, therefore, low Reynolds numbers) [2].…”

Section: External Flow Over a Spherementioning

confidence: 98%

“…A figure displaying the spread of the percent difference with the 2 published sources can be seen in Figure 16. Based on the close alignment with the Clift et al correlation [4] and low average percent difference with the Roos and Willmarth experimental data [24], the Fluent simulations are very successful at modeling the drag on a sphere with drift flow conditions. …”

Section: D Axisymmetric Drift Regime: Domain Size Mesh Refinementmentioning

confidence: 99%

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Flight and Stability of a Laser Inertial Fusion Energy Target in the Drift Region between Injection and the Reaction Chamber with Computational Fluid Dynamics

Mitori

2013

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“…8. The drag coefficient measured by Roos and Willmarth (1971) and the drag coefficients computed by Mittal (1999) and Sheard et al (2003) are also presented for comparison. The results of the present study match well with results of previous research.…”

Section: Laminar Flow Around a Spherementioning

confidence: 99%

Convergence Characteristics of Upwind Method for Modified Artificial Compressibility Method

Lee¹,

Lee²

2011

International Journal of Aeronautical and Space Sciences

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This paper investigates the convergence characteristics of the modified artificial compressibility method proposed by Turkel. In particular, a focus is mode on the convergence characteristics due to variation of the preconditioning factor (α u ) and the artificial compressibility (β) in conjunction with an upwind method. For the investigations, a code using the modified artificial compressibility is developed. The code solves the axisymmetric incompressible Reynolds averaged Navier-Stokes equations. The cell-centered finite volume method is used in conjunction with Roe's approximate Riemann solver for the inviscid flux, and the central difference discretization is used for the viscous flux. Time marching is accomplished by the approximated factorizationalternate direction implicit method. In addition, Menter's k-ω shear stress transport turbulence model is adopted for analysis of turbulent flows. Inviscid, laminar, and turbulent flows are solved to investigate the accuracy of solutions and convergence behavior in the modified artificial compressibility method. The possible reason for loss of robustness of the modified artificial compressibility method with α u >1.0 is given.

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Some experimental results on sphere and disk drag

Cited by 282 publications

References 18 publications

Global linear stability analysis of the wake and path of buoyancy-driven disks and thin cylinders

Global linear stability analysis of the wake and path of buoyancy-driven disks and thin cylinders

Flight and Stability of a Laser Inertial Fusion Energy Target in the Drift Region between Injection and the Reaction Chamber with Computational Fluid Dynamics

Convergence Characteristics of Upwind Method for Modified Artificial Compressibility Method

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