Numerical Investigation of Bubble‐induced Marangoni Convection

O’Shaughnessy, S.M.; Robinson, A.J.

doi:10.1111/j.1749-6632.2008.04332.x

Cited by 14 publications

(22 citation statements)

References 28 publications

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“…The effect of increasing Marangoni number under 0-g conditions has been investigated by O'Shaughnessy and Robinson [13]. Consistent with the findings in [13], thermocapillary convection causes the formation of a flow of liquid away from the bubble tip, which can be visualised by the way in which the temperature contours deflect away from the hot wall.…”

Section: Influence Of Masupporting

confidence: 59%

“…The efficacy of this correlation on the lower cold wall heat transfer enhancement was later confirmed by the numerical investigation of O'Shaughnessy and Robinson [13]. Before this, however, Petrovic et al [5] used the same correlation to predict the heat transfer rate from an upward facing surface with several gas bubbles attached to it.…”

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 77%

“…In [13] they investigated the influence of increasing the Marangoni number in 0-g and determined that thermocapillary convection enhanced the local heat flux to over 65% when compared with pure conduction. Enhancment of local wall heat transfer was calculated to occur over a distance of approximately seven bubble radii.…”

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 99%

“…O'Shaughnessy and Robinson [13,21,22] were the first to numerically simulate thermal Marangoni convection with the expressed goal of quantifying the local wall heat transfer distribution around the bubbles. In [13] they investigated the influence of increasing the Marangoni number in 0-g and determined that thermocapillary convection enhanced the local heat flux to over 65% when compared with pure conduction.…”

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 99%

“…The fluid motion near the wall reduces the thermal boundary layer thickness and results in higher heat transfer rates compared with the far field [13].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy

O’Shaughnessy

Robinson

2013

International Journal of Heat and Mass Transfer

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Thermal Marangoni convection about a 1 mm radius hemispherical air bubble attached to a heated wall immersed in a silicone oil layer of constant depth of 5 mm was numerically investigated. Tests were performed for a range of Marangoni numbers (145≤Ma≤915) with varying levels of gravitational acceleration between zero gravity and earth gravity in order to quantify the rates of heat transfer. For the zero gravity condition, a thermocapillary-driven vortex develops around the bubble extending the entire height of the channel. This flow structure causes a jet-like flow of heated liquid to emanate from the bubble tip which impinged on the cold wall. With the addition of gravity, a counter rotating secondary buoyancydriven vortex forms which reduces the size of the thermocapillary vortex and disrupts the jet flow from the bubble tip. The wall heat flux profiles indicate that under zero gravity, the peak heat fluxes increase monotonically with Ma with an area of influence that increases asymptotically with Ma. Likewise, under gravity conditions the peak heat flux also increases with Ma and for low Ma is higher than that of 0-g. However, the area of influence is considerably smaller and not sensitive to Ma or the level of gravity. Experimental validation of selected terrestrial gravity numerical results was obtained using particle image velocimetry (PIV) for low to moderate Marangoni numbers. For all experiments, steadystate Marangoni convection was observed. The experimental flow patterns showed good agreement with the numerical solutions.

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Section: Influence Of Masupporting

confidence: 59%

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 77%

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 99%

Section: Bhunia and Kamotani [Ref] Numerically Investigated 2dmentioning

confidence: 99%

“…The fluid motion near the wall reduces the thermal boundary layer thickness and results in higher heat transfer rates compared with the far field [13].…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy

O’Shaughnessy

Robinson

2013

International Journal of Heat and Mass Transfer

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Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

2020

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The authors report on the results of surface treatment experiments using a solid-state amplified laser source emitting laser pulses with a pulse duration of 10 ps. The laser source allows the generation of pulse trains (bursts) with an intra-burst pulse repetition rate of 80 MHz (pulse-to-pulse time interval about 12.5 ns) with up to eight pulses per burst. In this study a wavelength of 1064 nm was used to investigate both ablation of material and laser-induced surface modifications occuring in metallic implant alloys CoCrMo (cobalt-chromium-molybdenum) and TiAlV (titanium-aluminum-vanadium) in dependence of the number of pulses and fluences per pulse in the burst. By using the burst mode, a smoothing effect occurs in a certain parameter range, resulting in very low surface roughness of the generated microstructures. It is demonstrated that at fluences per pulse which are smaller than the material-specific ablation threshold, a self-organized pore formation takes place if a defined number of pulses per burst is used. Thus, the advantage of the MHz burst mode in terms of a possible surface modification is established.

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In situ observation of the impact of hydrogen bubbles in Al–Cu melt on directional dendritic solidification

et al. 2021

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Much research has already been focused on the solid-bubble interaction in the interdendritic space for solidifying materials. However, commonly, bubble nucleation is not limited to the mushy zone but also occurs in the liquid melt. In the present research on an Al-$$10 \, \%\mathrm {wt. \,}$$ 10 % wt . Cu alloy, the interaction between these bubbles and the approaching solidification front becomes apparent under in situ X-radiography and allows for new insights into the influence of bubbles on the solidifying microstructure. The observed effects comprise bulging of the solidification front toward the bubble, bending of dendrites in front of the bubble, coronal outgrowths surrounding the bubbles, as well as bubble growth, bubble pushing, and bubble eruption. It is found that for the present Al–Cu alloy, the local variation in the solidification speed can be attributed to the bubbles’ insulating properties. The range of this effect was observed to be up to $$900 \,\upmu \text {m}$$ 900 μ m , depending on the bubble diameter, locally increasing solidification speed by up to $$350 \, \%$$ 350 % . The influences of Marangoni vortices and coronal nucleation of misoriented dendrites around bubbles on the homogeneity of the microstructure are discussed. A comparison with experiments on model alloys and simulations from various other studies highlights the similarities and differences to this metallic alloy system.

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Numerical Investigation of Bubble‐induced Marangoni Convection

Cited by 14 publications

References 28 publications

Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy

Heat transfer near an isolated hemispherical gas bubble: The combined influence of thermocapillarity and buoyancy

Surface treatment on cobalt and titanium alloys using picosecond laser pulses in burst mode

In situ observation of the impact of hydrogen bubbles in Al–Cu melt on directional dendritic solidification

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