dorsal/arxiv
View SchemaExtraction of coherent structures in a rotating turbulent flow experiment
| Authors | Jori E. Ruppert-Felsot, Olivier Praud, Eran Sharon, Harry L. Swinney |
|---|---|
| Categories | |
| ArXiv ID | physics/0410161 |
| URL | https://arxiv.org/abs/physics/0410161 |
| DOI | 10.1103/PhysRevE.72.016311 |
Abstract
The discrete wavelet packet transform (DWPT) and discrete wavelet transform (DWT) are used to extract and study the dynamics of coherent structures in a turbulent rotating fluid. Three-dimensional (3D) turbulence is generated by strong pumping through tubes at the bottom of a rotating tank (48.4 cm high, 39.4 cm diameter). This flow evolves toward two-dimensional (2D) turbulence with increasing height in the tank. Particle Image Velocimetry (PIV) measurements on the quasi-2D flow reveal many long-lived coherent vortices with a wide range of sizes. The vorticity fields exhibit vortex birth, merger, scattering, and destruction. We separate the flow into a low-entropy ``coherent'' and a high-entropy ``incoherent'' component by thresholding the coefficients of the DWPT and DWT of the vorticity fields. Similar thresholdings using the Fourier transform and JPEG compression together with the Okubo-Weiss criterion are also tested for comparison. We find that the DWPT and DWT yield similar results and are much more efficient at representing the total flow than a Fourier-based method. Only about 3% of the large-amplitude coefficients of the DWPT and DWT are necessary to represent the coherent component and preserve the vorticity probability density function, transport properties, and spatial and temporal correlations. The remaining small amplitude coefficients represent the incoherent component, which has near Gaussian vorticity PDF, contains no coherent structures, rapidly loses correlation in time, and does not contribute significantly to the transport properties of the flow. This suggests that one can describe and simulate such turbulent flow using a relatively small number of wavelet or wavelet packet modes.
{
"annotation_id": "1897d19f-6ec3-4b5d-bd71-fa2f4150dfec",
"date_created": "2026-03-02T18:00:53.625000Z",
"date_modified": "2026-03-02T18:00:53.625000Z",
"file_hash": "fc27bfa41787430a565ef68e3c796a024f564b90bdf384750ef216e039fc7fbd",
"private": false,
"record": {
"abstract": "The discrete wavelet packet transform (DWPT) and discrete wavelet transform\n(DWT) are used to extract and study the dynamics of coherent structures in a\nturbulent rotating fluid. Three-dimensional (3D) turbulence is generated by\nstrong pumping through tubes at the bottom of a rotating tank (48.4 cm high,\n39.4 cm diameter). This flow evolves toward two-dimensional (2D) turbulence\nwith increasing height in the tank. Particle Image Velocimetry (PIV)\nmeasurements on the quasi-2D flow reveal many long-lived coherent vortices with\na wide range of sizes. The vorticity fields exhibit vortex birth, merger,\nscattering, and destruction. We separate the flow into a low-entropy\n``coherent\u0027\u0027 and a high-entropy ``incoherent\u0027\u0027 component by thresholding the\ncoefficients of the DWPT and DWT of the vorticity fields. Similar thresholdings\nusing the Fourier transform and JPEG compression together with the Okubo-Weiss\ncriterion are also tested for comparison. We find that the DWPT and DWT yield\nsimilar results and are much more efficient at representing the total flow than\na Fourier-based method. Only about 3% of the large-amplitude coefficients of\nthe DWPT and DWT are necessary to represent the coherent component and preserve\nthe vorticity probability density function, transport properties, and spatial\nand temporal correlations. The remaining small amplitude coefficients represent\nthe incoherent component, which has near Gaussian vorticity PDF, contains no\ncoherent structures, rapidly loses correlation in time, and does not contribute\nsignificantly to the transport properties of the flow. This suggests that one\ncan describe and simulate such turbulent flow using a relatively small number\nof wavelet or wavelet packet modes.",
"arxiv_id": "physics/0410161",
"authors": [
"Jori E. Ruppert-Felsot",
"Olivier Praud",
"Eran Sharon",
"Harry L. Swinney"
],
"categories": [
"physics.flu-dyn"
],
"doi": "10.1103/PhysRevE.72.016311",
"title": "Extraction of coherent structures in a rotating turbulent flow experiment",
"url": "https://arxiv.org/abs/physics/0410161"
},
"schema_id": "dorsal/arxiv",
"source": {
"execution_id": "d03acb9f-73d0-4f34-825c-5d4e42b5a1a3",
"id": "arXiv Dataset IDs",
"type": "Model",
"variant": "snapshot-2026-03-01",
"version": "0.1.0"
},
"user_id": 1000002
}