3D trapping of microbubbles by the Marangoni force

2021 ◽  
Author(s):  
Julio Sarabia Alonso ◽  
Ruben Ramos-Garcia ◽  
Svetlana Mansurova ◽  
Jose Ortega ◽  
F. M. Muñoz-Pérez
Keyword(s):  
Marangoni Force

scholarly journals Surface viscosity and Marangoni stresses at surfactant laden interfaces

2016 ◽  
Vol 792 ◽  
pp. 712-739 ◽  
Author(s):  
Gwynn J. Elfring ◽  
L. Gary Leal ◽  
Todd M. Squires
Keyword(s):  
Material Properties ◽  
Finite Time ◽  
Time Scale ◽  
Surfactant Concentration ◽  
Marangoni Flow ◽  
Force Measurements ◽  
Surface Viscosity ◽  
Surface Shear ◽  
Marangoni Force ◽  
Soluble Surfactant

We calculate here the force on a probe at a viscous, compressible interface, laden with soluble surfactant that equilibrates on a finite time scale. The motion of the probe through the interface drives variations in the surfactant concentration at the interface that in turn leads to a Marangoni flow that contributes to the force on the probe. We demonstrate that the Marangoni force on the probe depends non-trivially on the surface shear and dilatational viscosities of the interface indicating the difficulty in extracting these material properties from force measurements at compressible interfaces.

scholarly journals Relationship among Welding Defects with Convection and Material Flow Dynamic Considering Principal Forces in Plasma Arc Welding

Metals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1444
Author(s):  
Huu Loc Nguyen ◽  
Anh Van Nguyen ◽  
Han Le Duy ◽  
Thanh-Hai Nguyen ◽  
Shinichi Tashiro ◽  
...  
Keyword(s):  
Weld Pool ◽  
Material Flow ◽  
Arc Welding ◽  
Welding Current ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Flow Dynamic ◽  
Pool Surface ◽  
Welding Defects ◽  
Marangoni Force

The material flow dynamic and velocity distribution on the melted domain surface play a crucial role on the joint quality and formation of welding defects. In this study, authors investigated the effects of the low and high currents of plasma arc welding on the material flow and thermodynamics of molten pool and its relationship to the welding defects. The high-speed video camera (HSVC) was used to observe the convection of the melted domain and welded-joint appearance. Furthermore, to consider the Marangoni force activation, the temperature on the melted domain was measured by a thermal HSVC. The results revealed that the velocity distribution on the weld pool surface was higher than that inside the molten weld pool. Moreover, in the case of 80 A welding current, the convection speed of molten was faster than that in other cases (120 A and 160 A). The serious undercut and humping could be seen on the top surface (upper side) and unstable weld bead was visualized on the back side (bottom surface). In the case of 160 A welding current, the convection on the weld pool surface was much more complex in comparison with 80 A and 120 A cases. The excessive convex defect at the bottom side and the concave defect at the top surface were observed. In the case of 120 A welding current, two convection patterns with the main flow in the backward direction were seen. Almost no welding defect could be found. The interaction between the shear force and Marangoni force played a solid state on the convection and heat transportation processes in the plasma arc welding process.

Oscillation of a microbubble by means of Marangoni force

2020 ◽  
Author(s):  
Francisco Misael Muñoz Pérez ◽  
José Gabriel Ortega Mendoza ◽  
Arturo Guzmán Barraza
Keyword(s):  
Marangoni Force

scholarly journals Material Flow Behavior on Weld Pool Surface in Plasma Arc Welding Process Considering Dominant Driving Forces

2020 ◽  
Vol 10 (10) ◽  
pp. 3569 ◽  
Author(s):  
Manh Ngo Huu ◽  
Anh Nguyen Van ◽  
Tuan Nguyen Van ◽  
Dang Tran Hai ◽  
Thanh Nguyen Van ◽  
...  
Keyword(s):  
Weld Pool ◽  
Material Flow ◽  
Arc Welding ◽  
Shear Force ◽  
Driving Forces ◽  
Flow Behavior ◽  
Shielding Gas ◽  
Pool Surface ◽  
Marangoni Force ◽  
Weld Pool Surface

In this study, the effect of oxygen in the shielding gas on the material flow behavior of the weld pool surface was discussed to clarify the dominant driving weld pool force in keyhole plasma arc welding (KPAW). To address this issue, the convection flow on the top surface of weld pool was observed using a high-speed video camera. The temperature distribution on the surface along keyhole wall was measured using the two-color pyrometry method to confirm the Marangoni force activity on the weld pool. The results show that the inclination angle of the keyhole wall (keyhole shape) increased especially near the top surface due to the decrease in the surface tension of weld pool through surface oxidation when a shielding gas of Ar + 0.5% O2 was used. Due to the change in the keyhole shape, the upward and backward shear force compositions created a large inclination angle at the top surface of the keyhole. From the temperature measurement results, the Marangoni force was found to alter the direction when 0.5% O2 was mixed with the shielding gas. The shear force was found to be the strongest force among the four driving forces. The buoyant force and Lorentz force were very weak. The Marangoni force was stronger than the Lorentz force but was weaker than shear force. The interaction of shear force and Marangoni force controlled the behavior and speed of material flow on the weld pool surface. A strong upward and backward flow was observed in the case of mixture shielding gas, whereas a weak upward flow was observed for pure Ar. The heat transportation due to the weld pool convection significantly changed when only a small amount of oxygen was admixed in the shielding gas. The results can be applied to control the penetration ratio in KPAW.

Heating Analysis of a Water Droplet in Between Multi-Wall Hydrophobic Surfaces

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Abdullah Al-Sharafi ◽  
Bekir S. Yilbas ◽  
Ahmet Z. Sahin ◽  
Hussain Al-Qahtani
Keyword(s):  
Thermal Field ◽  
Thermal Response ◽  
Bond Number ◽  
Heat Diffusion ◽  
Bottom Plate ◽  
Experimental Conditions ◽  
Particle Injection ◽  
Marangoni Force ◽  
Heated Fluid ◽  
Temperature Enhancement

Abstract Droplet heat transfer in between parallelly located superhydrophobic plates is examined. The thermal field inside the droplet is predicted by adopting the experimental conditions. The influence of plates spacing (heights) on the thermal response of the droplet fluid is investigated. Particle injection velocimetry (PIV) is used to validate the velocity predictions. We demonstrated that predictions of flow velocity are in agreement with those of the PIV results. The heating of the droplet in the absence of the top plate gives four circulation cells in the droplet. Once the top superhydrophobic plate is introduced, the flow structure alters, and the number of the circulating structures reduces to two. Lowering the height of the plates increases the droplet Laplace pressure while modifying the fluid flow and thermal behavior. The Bond number is lower than one for all the cases considered; hence, demonstrating that the Marangoni force affects the formation of the circulation cells. The cells redistribute the heated fluid in the droplet interior, which is clearly apparent for the plates with small heights. Temperature enhancement in the droplet bottom section is attributed to the flow current formed due to heat diffusion. The Nusselt number corresponding to the bottom plate increases as the plate heights reduces; however, the opposite is true for that corresponding to the top plate.

scholarly journals Marangoni force-driven manipulation of photothermally-induced microbubbles

2018 ◽  
Vol 26 (6) ◽  
pp. 6653 ◽  
Author(s):  
J. G. Ortega-Mendoza ◽  
J. A. Sarabia-Alonso ◽  
P. Zaca-Morán ◽  
A. Padilla-Vivanco ◽  
C. Toxqui-Quitl ◽  
...  
Keyword(s):  
Marangoni Force

scholarly journals Study on Time Characteristics of Coupling Discharge in Pulsed Laser Induced Double-TIG Welding

2021 ◽  
Author(s):  
Xinkun Xu ◽  
Huanyu Yang ◽  
Liming Liu
Keyword(s):  
High Speed ◽  
Pulsed Laser ◽  
Pulse Action ◽  
Tig Welding ◽  
Duty Ratio ◽  
Regulation Mechanism ◽  
Arc Plasma ◽  
Existence Time ◽  
Arc Pressure ◽  
Marangoni Force

Abstract Based on the dynamic behavior of laser keyhole, the time characteristics of coupling discharge of heat source in pulsed laser induced double-TIG welding (LIDTW) are studied. The behaviors of arc plasma and laser keyhole were directly observed by high-speed camera and auxiliary illumination source. The physical characteristics of arc plasma were analyzed by spectrometer and arc quality analyzer. A physical model is established to reveal the regulation mechanism of time characteristics of coupling discharge. It is found that after laser pulse action the coupling discharge between keyhole plasma and double-arc plasma does not end immediately, and its time depends on the existence time of keyhole. During hybrid welding, when the combined force of arc pressure and Marangoni force can overcome the gravity, the liquid metal is forced out of the keyhole and the keyhole remains open. Improving the electron density of arc plasma and arc voltage and reducing the diameter of arc conductive channel by selecting appropriate parameters to is the key to prolong the existence time of keyhole, which is beneficial to improve the welding penetration. The coupling enhancement of double-arc electromagnetic field in LIDTW can effectively suppress keyhole backfill and increase the duty ratio of coupling discharge. When the total current intensity is 200 A, compared with laser induced single-TIG welding (LISTW), the existence time of keyhole in LIDTW increases by 77 %, the duty ratio of coupling discharge increases by 12 %, and the weld penetration increases by 29.2 %.

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