Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water
When a bubble rises freely in still water, it often moves along a zigzag or spiral trajectory. In order to explore the mechanism of this movement, an experiment was conducted to record the changes in the movement trajectory and bubble shape. The results show that this movement can be explained by th...
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MDPI AG
2023-05-01
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| Series: | Applied Sciences |
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| Online Access: | https://www.mdpi.com/2076-3417/13/11/6500 |
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| author | He Liu Yajie Zhang Yanju Wei Zhiqiang Mu Yajing Yang Muhammad Shahid Farooq |
| author_facet | He Liu Yajie Zhang Yanju Wei Zhiqiang Mu Yajing Yang Muhammad Shahid Farooq |
| author_sort | He Liu |
| collection | DOAJ |
| description | When a bubble rises freely in still water, it often moves along a zigzag or spiral trajectory. In order to explore the mechanism of this movement, an experiment was conducted to record the changes in the movement trajectory and bubble shape. The results show that this movement can be explained by the swing of trailing vortices and the change in vorticity. There is asymmetric shedding of the trailing vortices. The change in bubble velocity caused by the shedding of the bubble trailing vortices will lead to an asymmetric change in the vorticity of the trailing vortices. Two factors lead to an asymmetric change in the drag force of the trailing vortices on both sides of the bubble, resulting in the zigzag trajectory. Only when the aspect ratio <i>λ</i> reaches 2.0 will the bubble move along the zigzag. The trailing vortices moving in two orthogonal directions will lead to a spiral trajectory. The movement of the trailing vortices not only changes the trajectory of the bubble but also changes its shape. The effect of the trailing vortices on the bubble can be equivalent to a low-pressure area around a bubble. When a bubble moves along a zigzag trajectory, the low-pressure area at the trailing of a bubble swings back and forth in a plane, and the bubble is flatter. When moving along a spiral trajectory, the low-pressure area rotates around the trailing of the bubble and becomes more spherical. Compared with a zigzag trajectory, a bubble has a higher velocity and lower frequency when moving along a spiral trajectory. |
| first_indexed | 2024-03-11T03:11:29Z |
| format | Article |
| id | doaj.art-66e3cadce61249318127117ef0a7c830 |
| institution | Directory Open Access Journal |
| issn | 2076-3417 |
| language | English |
| last_indexed | 2024-03-11T03:11:29Z |
| publishDate | 2023-05-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Applied Sciences |
| spelling | doaj.art-66e3cadce61249318127117ef0a7c8302023-11-18T07:32:58ZengMDPI AGApplied Sciences2076-34172023-05-011311650010.3390/app13116500Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still WaterHe Liu0Yajie Zhang1Yanju Wei2Zhiqiang Mu3Yajing Yang4Muhammad Shahid Farooq5School of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Aerospace Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaSchool of Energy and Power Engineering, Xi’an Jiaotong University, Xi’an 710049, ChinaWhen a bubble rises freely in still water, it often moves along a zigzag or spiral trajectory. In order to explore the mechanism of this movement, an experiment was conducted to record the changes in the movement trajectory and bubble shape. The results show that this movement can be explained by the swing of trailing vortices and the change in vorticity. There is asymmetric shedding of the trailing vortices. The change in bubble velocity caused by the shedding of the bubble trailing vortices will lead to an asymmetric change in the vorticity of the trailing vortices. Two factors lead to an asymmetric change in the drag force of the trailing vortices on both sides of the bubble, resulting in the zigzag trajectory. Only when the aspect ratio <i>λ</i> reaches 2.0 will the bubble move along the zigzag. The trailing vortices moving in two orthogonal directions will lead to a spiral trajectory. The movement of the trailing vortices not only changes the trajectory of the bubble but also changes its shape. The effect of the trailing vortices on the bubble can be equivalent to a low-pressure area around a bubble. When a bubble moves along a zigzag trajectory, the low-pressure area at the trailing of a bubble swings back and forth in a plane, and the bubble is flatter. When moving along a spiral trajectory, the low-pressure area rotates around the trailing of the bubble and becomes more spherical. Compared with a zigzag trajectory, a bubble has a higher velocity and lower frequency when moving along a spiral trajectory.https://www.mdpi.com/2076-3417/13/11/6500zigzag and spiral trajectorythe swing of trailing vorticesthe change of vorticityoscillation frequencylow-pressure area |
| spellingShingle | He Liu Yajie Zhang Yanju Wei Zhiqiang Mu Yajing Yang Muhammad Shahid Farooq Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water Applied Sciences zigzag and spiral trajectory the swing of trailing vortices the change of vorticity oscillation frequency low-pressure area |
| title | Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water |
| title_full | Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water |
| title_fullStr | Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water |
| title_full_unstemmed | Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water |
| title_short | Characteristics and Mechanisms of the Zigzag and Spiral Movement of Rising Bubbles in Still Water |
| title_sort | characteristics and mechanisms of the zigzag and spiral movement of rising bubbles in still water |
| topic | zigzag and spiral trajectory the swing of trailing vortices the change of vorticity oscillation frequency low-pressure area |
| url | https://www.mdpi.com/2076-3417/13/11/6500 |
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