Oscillating convection modes in the surroundings of an air bubble under a horizontal heated wall

Chun, Ch.-H.; Raake, D.; Hansmann, G.

doi:10.1007/bf00211790

Cited by 27 publications

(15 citation statements)

References 7 publications

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“…The mentioned case of periodically oscillating flow of Mg= 18355 matches that result mentioned before by Raake et al [10], as oscillations were supposed to arise starting from a temperature gradient of 0.5 °C /mm, followed by high degree of oscillations at around of 1 °C/mm. According to figure 11, the discussed case of Mg= 18355, and rB /zB, ratio of bubble radius to its vertical expansion = 2.25, was expected by Chun et al al [3] to oscillate periodically. This matches our results.…”

Section: Resultsmentioning

confidence: 85%

“…One can notice an increase of the mean temperature in case of the larger bubble, due to the injection of more amount of air to the bubble. Further analysis of the temporal temperature variations at a discrete point around the bubble can help to evaluate the behaviour of the flow [3]. Figure 8 shows laminar flow fields around the injected bubble at different low Mg-number conditions, where no obvious temperature oscillations of amplitude higher than 0.03 °C appear.…”

Section: Resultsmentioning

confidence: 99%

“…Fig. 11: Mode selection on the plane of the modified Mg-number vs. the bubble geometry parameter rB /zB [3].…”

Section: Resultsmentioning

confidence: 99%

“…Wozniak et al [1,2] [1] the mean whole temperature gradient along the liquid matrix |∂T/∂Z|∞ is simply considered. In this work, the form used by Chun et al [3] is used, as both geometrical parameters of the bubble are considered. Moreover, the actual temperature gradient near the bubble is used in the equation instead of the whole temperature gradient of the test fluid.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, one can purposefully use the temperature gradient to eliminate or move bubbles or drops suspended in liquid metals [5], as well as in other applications ICMFHT 102-2 like manufacturing of single-walled carbon nanotubes [6], monocrystal production, and investigating Flame spread above liquid fuels [7], to mention only a few examples. Many efforts have been made to study Marangoni convection, also to determine the behaviour of the flow, and the factors leading to instabilities of that flow like periodic oscillations or non-periodic ones till it turns to turbulent flow, [8], [9], [3], and [10]. Therefore, our work aims at developing a test cell for high Mg-numbers to study the flow behaviour of the examined volatile fluid, where high non-periodic oscillations are achieved.…”

Section: Introductionmentioning

confidence: 99%

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Preparatory Experiments on Oscillatory Thermocapillary bubble Convection

Tadrous¹,

Wozniak²

2019

Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer

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Thermocapillary-driven convection around a bubble under a heated wall is experimentally investigated under gravitational conditions. The induced flows are categorized into laminar, periodic oscillatory, and non-periodic oscillatory flow through the pattern of the tracer particle motion around the bubble using particle image velocimetry PIV, and through surface temperature variation using resistance temperature detectors (RTDs). Transient temperature development at a discrete point can reflect the fluctuations of the flow. Chaotic flows are observed in these experiments. They are distinguished from the periodic oscillatory flow through the non-periodicity of temperature fluctuations along a certain point around the bubble within the flow domain.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

“…Fig. 11: Mode selection on the plane of the modified Mg-number vs. the bubble geometry parameter rB /zB [3].…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Preparatory Experiments on Oscillatory Thermocapillary bubble Convection

Tadrous¹,

Wozniak²

2019

Proceedings of the 4th World Congress on Momentum, Heat and Mass Transfer

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Experimental Investigation of non‐periodic oscillations in a surface tension driven flow around a bubble

Tadrous

Wozniak

2021

Proc Appl Math and Mech

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Thermocapillary convection around an air bubble under a heated wall is experimentally investigated under gravitational conditions. The flow is basically studied through temperature fluctuation plots near the bubble periphery, which is subjected to an upward flow driving temperature gradient. This study illuminates the thermocapillary-buoyancy convective flow behaviour within the regime of non-periodic oscillations. Moreover, the fluid flow is qualitatively categorized according to the transient behaviour of the thermocapillary vortex boundary line around the bubble using the shadowgraph technique. A low viscous silicone oil as test fluid restricts reaching higher temperature gradients to avoid the formation of undesired vapour bubbles. However, pursuing the experiments under high pressures allowed reaching higher temperature gradients in order to achieve the non-periodic flow regime. Both periodic and chaotic oscillations of the liquid flow around the bubble were recorded. They were distinguished from each other through the periodicity of the visualized thermocapillary vortex boundary line movements. The recording of temperature fluctuations at positions near the bubble during a time period ∆t demonstrated the thermocapillary fluid flow behaviour at different Marangoni-numbers M g.

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