File:Simulation of von Karman street in flow around a disc - velocity (arrows) and vorticity (colours).webm
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Size of this JPG preview of this WEBM file: 800 × 450 pixels. Other resolutions: 320 × 180 pixels | 640 × 360 pixels | 1,024 × 576 pixels | 1,280 × 720 pixels | 2,880 × 1,620 pixels.
Original file (WebM audio/video file, VP9, length 3 min 15 s, 2,880 × 1,620 pixels, 3.41 Mbps overall, file size: 79.31 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 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. Colour is vorticity, with red clockwise and blue anticlockwise. Note that as vortex as shown by red/blue moves to the right, that arrows showing flow velocity rotate around max in vorticity (darkest red/blue). Technical details: Simulation box is nx=500 (flow direction) by ny=180 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. One frame every 25 steps. 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 | 19:57, 17 June 2023 | 3 min 15 s, 2,880 × 1,620 (79.31 MB) | Rpsear (talk | contribs) | Uploaded own work with UploadWizard |
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