Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis
Surface gravity wavepackets in intermediate water depth experiencing an abrupt depth decrease are investigated experimentally. The experiments provide validation for the second-order (in steepness) theory for narrow-banded surface gravity wavepackets experiencing a sudden depth transition derived in...
| Main Authors: | , , , |
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| Format: | Journal article |
| Language: | English |
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Cambridge University Press
2021
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| _version_ | 1826268779328307200 |
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| author | Li, Y Draycott, S Adcock, T Van Den Bremer, T |
| author_facet | Li, Y Draycott, S Adcock, T Van Den Bremer, T |
| author_sort | Li, Y |
| collection | OXFORD |
| description | Surface gravity wavepackets in intermediate water depth experiencing an abrupt depth decrease are investigated experimentally. The experiments provide validation for the second-order (in steepness) theory for narrow-banded surface gravity wavepackets experiencing a sudden depth transition derived in a companion paper (Li et al., J. Fluid Mech., 2021, 915, A71). We observe the generation of free second-order sub- and superharmonic wavepackets due to the sudden depth transition, in addition to changes to the main (first-order) wavepacket and its second-order bound waves. Locally, just after the step, this leads to the superposition of different wavepacket components. Thereafter, separation occurs because of the different group speeds of the free second-order sub- and superharmonic wavepackets compared with the main packet. Experiments show that the local superposition of waves can lead to significant amplification of wave crests near the top of a step, as predicted by theory. In addition to a step, we also experimentally examine more gradual depth changes in the form of 1 : 1 and 1 : 3 slopes to explore the limits of the theory's validity. Although we find small differences in amplitude and phase comparing these steep slopes with a step, these experiments suggest that the theoretical model derived in Part 1 for wavepackets travelling over a step is applicable to slopes steeper than 1 : 3. |
| first_indexed | 2024-03-06T21:14:51Z |
| format | Journal article |
| id | oxford-uuid:3f6c6163-a932-404d-9cdb-0e0ad00e3d18 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T21:14:51Z |
| publishDate | 2021 |
| publisher | Cambridge University Press |
| record_format | dspace |
| spelling | oxford-uuid:3f6c6163-a932-404d-9cdb-0e0ad00e3d182022-03-26T14:31:58ZSurface wavepackets subject to an abrupt depth change. Part II: experimental analysisJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:3f6c6163-a932-404d-9cdb-0e0ad00e3d18EnglishSymplectic ElementsCambridge University Press2021Li, YDraycott, SAdcock, TVan Den Bremer, TSurface gravity wavepackets in intermediate water depth experiencing an abrupt depth decrease are investigated experimentally. The experiments provide validation for the second-order (in steepness) theory for narrow-banded surface gravity wavepackets experiencing a sudden depth transition derived in a companion paper (Li et al., J. Fluid Mech., 2021, 915, A71). We observe the generation of free second-order sub- and superharmonic wavepackets due to the sudden depth transition, in addition to changes to the main (first-order) wavepacket and its second-order bound waves. Locally, just after the step, this leads to the superposition of different wavepacket components. Thereafter, separation occurs because of the different group speeds of the free second-order sub- and superharmonic wavepackets compared with the main packet. Experiments show that the local superposition of waves can lead to significant amplification of wave crests near the top of a step, as predicted by theory. In addition to a step, we also experimentally examine more gradual depth changes in the form of 1 : 1 and 1 : 3 slopes to explore the limits of the theory's validity. Although we find small differences in amplitude and phase comparing these steep slopes with a step, these experiments suggest that the theoretical model derived in Part 1 for wavepackets travelling over a step is applicable to slopes steeper than 1 : 3. |
| spellingShingle | Li, Y Draycott, S Adcock, T Van Den Bremer, T Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title | Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title_full | Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title_fullStr | Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title_full_unstemmed | Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title_short | Surface wavepackets subject to an abrupt depth change. Part II: experimental analysis |
| title_sort | surface wavepackets subject to an abrupt depth change part ii experimental analysis |
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