Performance of Various Fluid-Solid Coupling Methods for DNS of Particulate Flow

Uhlmann, Markus; Pinelli, Alfredo

doi:10.1007/1-4020-4977-3_22

Cited by 5 publications

(3 citation statements)

References 10 publications

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“…the flow is non-trivially unsteady in the fixed frame of reference; secondly, the use of a fractional step method introduces a "slip error" on the fluid-solid interface which is of order ∆t (cf. discussion in Uhlmann, 2005b). From table 8 it can be seen that the respective errors of all particle-related degrees of freedom (except for u pH at D/∆x = 48) behave in a monotonic fashion at this lower value of the CFL number, i.e.…”

Section: Steady Oblique Regimementioning

confidence: 82%

The motion of a single heavy sphere in ambient fluid: A benchmark for interface-resolved particulate flow simulations with significant relative velocities

Uhlmann

Dušek

2014

International Journal of Multiphase Flow

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Detailed data describing the motion of a rigid sphere settling in unperturbed fluid is generated by means of highly-accurate spectral/spectral-element simulations with the purpose of serving as a future benchmark case. A single solid-to-fluid density ratio of 1.5 is chosen, while the value of the Galileo number is varied from 144 to 250 such as to cover the four basic regimes of particle motion (steady vertical, steady oblique, oscillating oblique, chaotic). This corresponds to a range of the particle Reynolds number from 185 to 365. In addition to the particle velocity data, extracts of the fluid velocity field are provided, as well as the pressure distribution on the sphere's surface. Furthermore, the same solid-fluid system is simulated with a particular non-boundary-conforming approach, i.e. the immersed boundary method proposed by Uhlmann (2005a), using various spatial resolutions. It is shown that the current benchmark case allows to adjust the resolution requirements for a given error tolerance in each flow regime.

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Section: Steady Oblique Regimementioning

confidence: 82%

The motion of a single heavy sphere in ambient fluid: A benchmark for interface-resolved particulate flow simulations with significant relative velocities

Uhlmann

Dušek

2014

International Journal of Multiphase Flow

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“…For reasons of efficiency, forcing is only applied to the surface of the spheres, leaving the flow field inside the particles to develop freely. Fadlun, Verzicco, Orlandi, and Mohd-Yusof (2000) have demonstrated that the external flow is essentially unchanged by this procedure; in Uhlmann (2005b) it was confirmed that the impact upon the particle motion is indeed small. Figure 1 shows the distribution of forcing points on the surface of a sphere with diameter D/∆x = 12.8 and the corresponding Eulerian grid in the vicinity.…”

Section: Methodsmentioning

confidence: 82%

Interface-resolved direct numerical simulation of vertical particulate channel flow in the turbulent regime

2008

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We have conducted a direct numerical simulation (DNS) study of dilute turbulent particulate flow in a vertical plane channel, considering thousands of finite-size rigid particles with resolved phase interfaces. The particle diameter corresponds to approximately 11 wall units and their terminal Reynolds number is set to 136. The fluid flow with bulk Reynolds number 2700 is directed upward, which maintains the particles suspended upon average. Two density ratios were simulated, differing by a factor of 4.5. The corresponding Stokes numbers of the two flow cases were O(10) in the near-wall region and O(1) in the outer flow. We have observed the formation of large-scale elongated streak-like structures with streamwise dimensions of the order of 8 channel half-widths and cross-stream dimensions of the order of one half-width. At the same time, we have found no evidence of significant formation of particle clusters, which suggests that the large structures are due to an intrinsic instability of the flow, triggered by the presence of the particles. It was found that the mean fluid velocity profile tends towards a concave shape, and the turbulence intensity as well as the normal stress anisotropy are strongly increased. The effect of varying the Stokes number while maintaining the buoyancy, particle size and volume fraction constant was relatively weak.

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“…While Uhlmann's (2005a) original method and successive similar methods; for example, Kempe and Fröhlich (2012), and Yang et al (2009) used Lagrangian forcing points only on the immersed boundary itself, the method described above also places Lagrangian points inside the immersed boundary (Uhlmann, 2005b). In the following, several test case flows are simulated using both types of Lagrangian-point placement allowing a direct assessment of validity and accuracy of the two forcing point strategies.…”

Section: Example Calculationsmentioning

confidence: 99%