File:Simulation of von Karman street in flow around a disc - with streamlines.webm
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Size of this JPG preview of this WEBM file: 800 × 267 pixels. Other resolutions: 320 × 107 pixels | 640 × 213 pixels | 1,024 × 341 pixels | 1,280 × 427 pixels | 4,800 × 1,600 pixels.
Original file (WebM audio/video file, VP9, length 1 min 46 s, 4,800 × 1,600 pixels, 9.2 Mbps overall, file size: 115.98 MB)
Captions
Captions
Computer simulation of flow around a disc (so applies to flow around a long cylinder) at a Reynolds number 100 where vortices (shown as loops in the streamlines) form and detach from the disc, forming a von Karman street
Summary[edit]
| Description |
English: Lattice-Boltzmann simulation (in 2D) of flow round a disc (radius 20 lattice sites) at a Reynolds number of 100 (using diameter as lengthscale). Around a reduced time of 10, the instability studied by von Karman and others sets in and the wake becomes unstable and starts to oscillate up and down every few reduced time units. It sheds vortices downstream, with alternate vortices shed at the top and bottom of the obstacle to flow. This pattern of vortex shedding forms a "von Karman street" of vortices seen in the second half of this movie.
A von Karman street is characteristic of intermediate, around 100, values of Reynolds numbers. The curves shown are streamlines, which are tangent curves to the flowfield at each point. Vortices show up as loops in the streamlines. Note that the loops/vortices that detach from the top and bottom halves of the disc rotate in opposite directions. Technical details: Simulation box is nx=420 (flow direction) by ny=140 lattice sites, Zou-He BC at left (entrance) sets flow speed to 0.04 in LB units, kinematic viscosity 0.012. Lattice Boltzmann code modified version of Palabos (U Geneva) Python LB code. PBCs along vertical axis and note that for convenience simulation box is quite small so there will be finite size effects. |
| Date | |
| Source | Own work |
| Author | Rpsear |
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| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 20:31, 5 August 2023 | 1 min 46 s, 4,800 × 1,600 (115.98 MB) | Rpsear (talk | contribs) | Uploaded own work with UploadWizard |
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