Vortex ring head-on collision with a heated vertical plate

Arévalo, Gabriel; Hernández, R. H.; Nicot, Christian; Plaza, F.

doi:10.1063/1.2759880

Cited by 14 publications

(20 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Many tests were performed where only thermal data were recorded and it was found that these high levels of localized heat transfer were consistently present and always at least double the free convection level. This is in stark contrast to the value of 15 % reported from spatially averaged measurements (Arévalo et al 2007) and illustrates that the vortex has a very localized but dominant impact on the convection.…”

Section: Vortex-ring-wall Interaction and Resulting Heat Transfercontrasting

confidence: 54%

“…Vortex rings have been extensively investigated and are very well understood from a fluid mechanics standpoint (Shariff & Leonard 1992) but not much work is available considering vortex-ring flows in combination with heat transfer. In a recent experimental investigation (Arévalo et al 2007) a vortex ring was created in air and allowed to impact on a heated vertical plate. The spatially averaged heat transfer from the surface was found to increase by up to 15 % over natural convection levels while the vortex was in contact with the surface.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The role of large-scale vortical structures in transient convective heat transfer augmentation

2013

View full text Add to dashboard Cite

The physical mechanism by which large-scale vortical structures augment convective heat transfer is a fundamental problem of turbulent flows. To investigate this phenomenon, two separate experiments were performed using simultaneous heat transfer and flow field measurements to study the vortex-wall interaction. Individual vortices were identified and studied both as part of a turbulent stagnation flow and as isolated vortex rings impacting on a surface. By examining the temporal evolution of both the flow field and the resulting heat transfer, it was observed that the surface thermal transport was governed by the transient interaction of the vortical structure with the wall. The magnitude of the heat transfer augmentation was dependent on the instantaneous strength, size and position of the vortex relative to the boundary layer. Based on these observations, an analytical model was developed from first principles that predicts the time-resolved surface convection using the transient properties of the vortical structure during its interaction with the wall. The analytical model was then applied, first to the simplified vortex ring model and then to the more complex stagnation region experiments. In both cases, the model was able to accurately predict the time-resolved convection resulting from the vortex interactions with the wall. These results reveal the central role of large-scale turbulent structures in the augmentation of thermal transport and establish a simple model for quantitative predictions of transient heat transfer.

show abstract

Section: Vortex-ring-wall Interaction and Resulting Heat Transfercontrasting

confidence: 54%

Section: Introductionmentioning

confidence: 99%

The role of large-scale vortical structures in transient convective heat transfer augmentation

2013

View full text Add to dashboard Cite

show abstract

“…Recently, different experimental works have studied the collision of single vortex rings with vertical heated walls. [10][11][12] Arévalo et al 10 studied the interaction of a vortex ring in air in collision with a vertical heated wall, their results indicated that there was an increment of the heat transfer as a result of the impact which increases with the vortex Reynolds number. Later, Arévalo et al 11 expanded their study and conducted measurements with the particle image velocimetry (PIV) technique to show that the vorticity and shear stresses are the basic ingredients to enhance the heat transfer.…”

Section: Introductionmentioning

confidence: 97%

“…Different wall temperatures, Reynolds numbers, and piston stroke ratios are considered. Previous works [10][11][12] have shown that the interaction of the vortex ring and the thermal boundary layer generates an asymmetric expansion of the ring. We will show that this asymmetry is also observed in the trajectory of the vortex ring during collision.…”

Section: Introductionmentioning

confidence: 99%

Interaction of a vortex ring with a natural convective layer

et al. 2014

View full text Add to dashboard Cite

We study the dynamics of the interaction of a vortex ring with a shear flow, generated by a natural convective layer. Laminar vortex rings were generated in water with a piston-cylinder arrangement. To generate the shear flow, a vertical wall was heated by a thermal bath held at constant temperature to produce a laminar and stable thermal boundary layer with a Grashof number of O(108). Measurements of the two-dimensional velocity field were obtained with a time resolved particle image velocimetry technique. Additionally, a 3D numerical model was used to simulate the experimental conditions. We mainly conducted experiments for the piston stroke L/D0 = 1 and Re of O(1000). The velocity ratio r = Uvi/Ush (where Uvi is the initial vortex velocity and Ush is the maximum velocity of the shear layer) was in the range 2.2 ⩽ r ⩽ 3.6. The results show that as the vortex approaches the shear layer, the ring expands and stretches mainly in the vertical direction and tilts slightly forming an angle between the wall and the ring plane which increases to about 3°. The rate of reduction of circulation is slower at the lower section of the vortex ring indicating that the momentum transport is more significant in this region. Moreover, the vortex circulation at the lower section increases to about 20% compared to the isothermal case. An analysis of the different mechanisms leading to this ring-shear layer interaction is presented and comparisons with reported data are discussed.

show abstract

“…1 The mechanism has revealed particular features that make the vortex ring a realistic candidate to enhance heat transfer from small electronic devices. A simplified situation involving this collision mechanism has been reported by other authors providing important insight on vortex stretching [2][3][4] and pressure gradients 4,5 at the wall, where the vortex core could be responsible for local and peaked shear stresses.…”

Section: Introductionmentioning

confidence: 99%

Particle image velocimetry measurements of vortex rings head-on collision with a heated vertical plate

et al. 2010

Self Cite

View full text Add to dashboard Cite

We report particle image velocimetry measurements of the collision of a vortex ring with a heated wall kept at constant temperature. We consider the case when both the vortex ring and the thermal boundary layer generated by the vertical heated wall are stable and laminar prior to any interaction. The impingement process can be divided into two parts. ͑i͒ A ring-driven stage, where the vortex ring grows in diameter while approaching the wall and therefore it sweeps progressively an increased surface on the wall. ͑ii͒ A boundary layer-driven stage, where the vortex ring moves upward due to the thermal convective motion generated by the heated wall. In some cases, the head-on collision triggers the ring's azimuthal instability as revealed by the formation of vortical structures arranged on a wavy starlike pattern and confirmed by flow visualizations. A single collision generates important velocity gradients and shear stresses along the wall accompanied with the creation of local vorticity normal to the vertical heated wall. Peak wall shear stresses occur near the point of impact of the vortex ring core.

show abstract

Vortex ring head-on collision with a heated vertical plate

Cited by 14 publications

References 14 publications

The role of large-scale vortical structures in transient convective heat transfer augmentation

The role of large-scale vortical structures in transient convective heat transfer augmentation

Interaction of a vortex ring with a natural convective layer

Particle image velocimetry measurements of vortex rings head-on collision with a heated vertical plate

Contact Info

Product

Resources

About