The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient
Thermovibrational flow can be seen as a variant of standard thermogravitational convection where steady gravity is replaced by a time-periodic acceleration. As in the parent phenomena, this type of thermal flow is extremely sensitive to the relative directions of the acceleration and the prevailing...
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MDPI AG
2021-01-01
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| Series: | Fluids |
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| Online Access: | https://www.mdpi.com/2311-5521/6/1/30 |
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| author | Georgie Crewdson Marcello Lappa |
| author_facet | Georgie Crewdson Marcello Lappa |
| author_sort | Georgie Crewdson |
| collection | DOAJ |
| description | Thermovibrational flow can be seen as a variant of standard thermogravitational convection where steady gravity is replaced by a time-periodic acceleration. As in the parent phenomena, this type of thermal flow is extremely sensitive to the relative directions of the acceleration and the prevailing temperature gradient. Starting from the realization that the overwhelming majority of research has focused on circumstances where the directions of vibrations and of the imposed temperature difference are perpendicular, we concentrate on the companion case in which they are parallel. The increased complexity of this situation essentially stems from the properties that are inherited from the corresponding case with steady gravity, i.e., the standard Rayleigh–Bénard convection. The need to overcome a threshold to induce convection from an initial quiescent state, together with the opposite tendency of acceleration to damp fluid motion when its sign is reversed, causes a variety of possible solutions that can display synchronous, non-synchronous, time-periodic, and multi-frequency responses. Assuming a square cavity as a reference case and a fluid with Pr = 15, we tackle the problem in a numerical framework based on the solution of the governing time-dependent and non-linear equations considering different amplitudes and frequencies of the applied vibrations. The corresponding vibrational Rayleigh number spans the interval from <i>Ra<sub>ω</sub></i> = 10<sup>4</sup> to <i>Ra<sub>ω</sub></i> = 10<sup>6</sup>. It is shown that a kaleidoscope of possible variants exist whose nature and variety calls for the simultaneous analysis of their temporal and spatial behavior, thermofluid-dynamic (TFD) distortions, and the Nusselt number, in synergy with existing theories on the effect of periodic accelerations on fluid systems. |
| first_indexed | 2024-03-09T05:31:40Z |
| format | Article |
| id | doaj.art-c1bd2e1a39204636a3d3af50c710806c |
| institution | Directory Open Access Journal |
| issn | 2311-5521 |
| language | English |
| last_indexed | 2024-03-09T05:31:40Z |
| publishDate | 2021-01-01 |
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| series | Fluids |
| spelling | doaj.art-c1bd2e1a39204636a3d3af50c710806c2023-12-03T12:32:30ZengMDPI AGFluids2311-55212021-01-01613010.3390/fluids6010030The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature GradientGeorgie Crewdson0Marcello Lappa1Department of Mechanical and Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UKDepartment of Mechanical and Aerospace Engineering, University of Strathclyde, James Weir Building, 75 Montrose Street, Glasgow G1 1XJ, UKThermovibrational flow can be seen as a variant of standard thermogravitational convection where steady gravity is replaced by a time-periodic acceleration. As in the parent phenomena, this type of thermal flow is extremely sensitive to the relative directions of the acceleration and the prevailing temperature gradient. Starting from the realization that the overwhelming majority of research has focused on circumstances where the directions of vibrations and of the imposed temperature difference are perpendicular, we concentrate on the companion case in which they are parallel. The increased complexity of this situation essentially stems from the properties that are inherited from the corresponding case with steady gravity, i.e., the standard Rayleigh–Bénard convection. The need to overcome a threshold to induce convection from an initial quiescent state, together with the opposite tendency of acceleration to damp fluid motion when its sign is reversed, causes a variety of possible solutions that can display synchronous, non-synchronous, time-periodic, and multi-frequency responses. Assuming a square cavity as a reference case and a fluid with Pr = 15, we tackle the problem in a numerical framework based on the solution of the governing time-dependent and non-linear equations considering different amplitudes and frequencies of the applied vibrations. The corresponding vibrational Rayleigh number spans the interval from <i>Ra<sub>ω</sub></i> = 10<sup>4</sup> to <i>Ra<sub>ω</sub></i> = 10<sup>6</sup>. It is shown that a kaleidoscope of possible variants exist whose nature and variety calls for the simultaneous analysis of their temporal and spatial behavior, thermofluid-dynamic (TFD) distortions, and the Nusselt number, in synergy with existing theories on the effect of periodic accelerations on fluid systems.https://www.mdpi.com/2311-5521/6/1/30thermovibrational convectiongravity modulationthermofluid-dynamic distortionspatterning behavior |
| spellingShingle | Georgie Crewdson Marcello Lappa The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient Fluids thermovibrational convection gravity modulation thermofluid-dynamic distortions patterning behavior |
| title | The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient |
| title_full | The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient |
| title_fullStr | The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient |
| title_full_unstemmed | The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient |
| title_short | The Zoo of Modes of Convection in Liquids Vibrated along the Direction of the Temperature Gradient |
| title_sort | zoo of modes of convection in liquids vibrated along the direction of the temperature gradient |
| topic | thermovibrational convection gravity modulation thermofluid-dynamic distortions patterning behavior |
| url | https://www.mdpi.com/2311-5521/6/1/30 |
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