Numerical simulations of internal wave generation by convection in water
Water's density maximum at 4[superscript ∘]C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4[superscript ∘]C, but stably stratified above 4[superscript ∘]C. We present numerical simulations of a wa...
| Main Authors: | , , , , , , |
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| Format: | Article |
| Language: | English |
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American Physical Society
2015
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| Online Access: | http://hdl.handle.net/1721.1/97601 https://orcid.org/0000-0003-4761-4766 |
| _version_ | 1811071337310978048 |
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| author | Lecoanet, Daniel Le Bars, Michael Vasil, Geoffrey M. Brown, Benjamin P. Quataert, Eliot Oishi, Jeffrey S. Burns, Keaton James |
| author2 | Massachusetts Institute of Technology. Department of Physics |
| author_facet | Massachusetts Institute of Technology. Department of Physics Lecoanet, Daniel Le Bars, Michael Vasil, Geoffrey M. Brown, Benjamin P. Quataert, Eliot Oishi, Jeffrey S. Burns, Keaton James |
| author_sort | Lecoanet, Daniel |
| collection | MIT |
| description | Water's density maximum at 4[superscript ∘]C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4[superscript ∘]C, but stably stratified above 4[superscript ∘]C. We present numerical simulations of a waterlike fluid near its density maximum in a two-dimensional domain. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. To isolate the physical mechanism exciting internal waves, we use the spectral code dedalus to run several simplified model simulations of our more detailed simulation. We use data from the full simulation as source terms in two simplified models of internal-wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via the mechanical oscillator effect. We find excellent agreement between the waves generated in the full simulation and the simplified simulation implementing the bulk excitation mechanism. The interface forcing simulations overexcite high-frequency waves because they assume the excitation is by the “impulsive” penetration of plumes, which spreads energy to high frequencies. However, we find that the real excitation is instead by the “sweeping” motion of plumes parallel to the interface. Our results imply that the bulk excitation mechanism is a very accurate heuristic for internal-wave generation by convection. |
| first_indexed | 2024-09-23T08:49:35Z |
| format | Article |
| id | mit-1721.1/97601 |
| institution | Massachusetts Institute of Technology |
| language | English |
| last_indexed | 2024-09-23T08:49:35Z |
| publishDate | 2015 |
| publisher | American Physical Society |
| record_format | dspace |
| spelling | mit-1721.1/976012022-09-23T14:48:18Z Numerical simulations of internal wave generation by convection in water Lecoanet, Daniel Le Bars, Michael Vasil, Geoffrey M. Brown, Benjamin P. Quataert, Eliot Oishi, Jeffrey S. Burns, Keaton James Massachusetts Institute of Technology. Department of Physics Burns, Keaton James Water's density maximum at 4[superscript ∘]C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4[superscript ∘]C, but stably stratified above 4[superscript ∘]C. We present numerical simulations of a waterlike fluid near its density maximum in a two-dimensional domain. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. To isolate the physical mechanism exciting internal waves, we use the spectral code dedalus to run several simplified model simulations of our more detailed simulation. We use data from the full simulation as source terms in two simplified models of internal-wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via the mechanical oscillator effect. We find excellent agreement between the waves generated in the full simulation and the simplified simulation implementing the bulk excitation mechanism. The interface forcing simulations overexcite high-frequency waves because they assume the excitation is by the “impulsive” penetration of plumes, which spreads energy to high frequencies. However, we find that the real excitation is instead by the “sweeping” motion of plumes parallel to the interface. Our results imply that the bulk excitation mechanism is a very accurate heuristic for internal-wave generation by convection. Kavli Institute for Astrophysics and Space Research (Graduate Fellowship) National Science Foundation (U.S.). Graduate Research Fellowship (Grant 1122374) 2015-07-01T15:22:55Z 2015-07-01T15:22:55Z 2015-06 2015-04 2015-06-30T22:00:05Z Article http://purl.org/eprint/type/JournalArticle 1539-3755 1550-2376 http://hdl.handle.net/1721.1/97601 Lecoanet, Daniel, Michael Le Bars, Keaton J. Burns, Geoffrey M. Vasil, Benjamin P. Brown, Eliot Quataert, and Jeffrey S. Oishi. "Numerical simulations of internal wave generation by convection in water." Phys. Rev. E 91, 063016 (June 2015). © 2015 American Physical Society https://orcid.org/0000-0003-4761-4766 en http://dx.doi.org/10.1103/PhysRevE.91.063016 Physical Review E Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. American Physical Society application/pdf American Physical Society American Physical Society |
| spellingShingle | Lecoanet, Daniel Le Bars, Michael Vasil, Geoffrey M. Brown, Benjamin P. Quataert, Eliot Oishi, Jeffrey S. Burns, Keaton James Numerical simulations of internal wave generation by convection in water |
| title | Numerical simulations of internal wave generation by convection in water |
| title_full | Numerical simulations of internal wave generation by convection in water |
| title_fullStr | Numerical simulations of internal wave generation by convection in water |
| title_full_unstemmed | Numerical simulations of internal wave generation by convection in water |
| title_short | Numerical simulations of internal wave generation by convection in water |
| title_sort | numerical simulations of internal wave generation by convection in water |
| url | http://hdl.handle.net/1721.1/97601 https://orcid.org/0000-0003-4761-4766 |
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