Effect of surface-active contaminants on radial thermocapillary flows

Bickel, Thomas

doi:10.1140/epje/i2019-11896-5

Cited by 17 publications

(14 citation statements)

References 47 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In this section we present an analytical model we have developed to explain our simulations and experimental results. Similar configurations have been analytically analyzed 34 for an air-oil system. In that case, the effect of surfactants is much weaker (oil is a non-polar fluid).…”

Section: Discussionmentioning

confidence: 93%

Effect of insoluble surfactants on a thermocapillary flow

et al. 2021

View full text Add to dashboard Cite

The thermocapillary effect, arising flow due to a temperature gradient along a fluid interface, is the dominant effect in some industrial and microfluidic processes and must be studied in order to optimize them. In this work, we analyze how insoluble surfactants adsorbed at the interface can affect such a flow. In particular, we analyze the case where the thermocapillary flow is induced at the air-water interface by locally heating it with an infrared laser, setup that is used to manipulate floating particles through the generated flow.Since water is a polar fluid, the air-water interface is easily polluted by surfactants. We developed a numerical model considering the uncontrolled presence of surfactants, which evidences that the effect of the surface contamination cannot be neglected, even for small surfactants concentration. The results of this numerical model were compared with different experimental measurements: particle tracking velocimetry, convection cell radius measurements and thermography of the surface. All the experimental observations agree with the numerical model with the initial surface contamination being a fitting parameter. The model was then validated comparing its results with measurements for which a known quantity of surfactant was added to the interface. Finally, an analytical model was developed to explain the effects of the governing parameters, which agrees with the simulations and the experimental results. The developed models give us insights towards the miniaturization of the manipulation platform.

show abstract

Section: Discussionmentioning

confidence: 93%

Effect of insoluble surfactants on a thermocapillary flow

et al. 2021

View full text Add to dashboard Cite

show abstract

“…In the case of a particle straddling an interface the key parameter for the particle drag is the particle contact angle which determine the partition between the two fluids with different viscosities [6]. Hydrodynamics can also be used to treat the situation when surface active species are present at the interface; a relatively high surface concentration of such species confers specific surface viscosities to the interface and changes the flow boundary conditions (BC) [7] [8]. Even tiny quantity of such species may dramatically affect the BC as recently predicted [9].…”

Section: Introductionmentioning

confidence: 99%

Motion of micro- and nano- particles interacting with a fluid interface

Villa

Boniello

Stocco

et al. 2020

Advances in Colloid and Interface Science

View full text Add to dashboard Cite

In this article, we review both theoretical models and experimental results on the motion of micro-and nanoparticles that are close to a fluid interface or move in between two fluids. Viscous drags together with dissipations due to fluctuations of the fluid interface and its physicochemical properties affect strongly the translational and rotational drags of colloidal particles, which are subjected to Brownian motion in thermal equilibrium. Even if many theoretical and experimental investigations have been carried out, additional scientific efforts in hydrodynamics, statistical physics, wetting and colloid science are still needed to explain unexpected experimental results and to measure particle motion in time and space scales, which are not accessible so far.

show abstract

“…In order to understand this behavior, we visualize the surface excess concentration fields around the particles and revert once more to dimensional analysis. As compared to the clean interface, we need to introduce two additional dimensionless groups: a surface Péclet number, defined Pe s ¼ VR=D s , where D s is the surface diffusion coefficient, and the ratio between solutal and thermal Marangoni stresses, Π ¼ βΔT=ðδΓ 0 Þ [46]. Since the surface diffusion coefficient can easily be 2 orders of magnitude lower than the thermal diffusion coefficient [47], the transition Pe s ≃ 1 happens at a correspondingly lower ΔT, for which the surface excess concentration field starts to deviate significantly from the diffusion-dominated regime.…”

mentioning

confidence: 99%

Microscale Marangoni Surfers

et al. 2020

View full text Add to dashboard Cite

We apply laser light to induce the asymmetric heating of Janus colloids adsorbed at water-oil interfaces and realize active micrometric "Marangoni surfers." The coupling of temperature and surfactant concentration gradients generates Marangoni stresses leading to self-propulsion. Particle velocities span 4 orders of magnitude, from microns/s to cm/s, depending on laser power and surfactant concentration. Experiments are rationalized by finite elements simulations, defining different propulsion regimes relative to the magnitude of the thermal and solutal Marangoni stress components.

show abstract

Effect of surface-active contaminants on radial thermocapillary flows

Cited by 17 publications

References 47 publications

Effect of insoluble surfactants on a thermocapillary flow

Effect of insoluble surfactants on a thermocapillary flow

Motion of micro- and nano- particles interacting with a fluid interface

Microscale Marangoni Surfers

Contact Info

Product

Resources

About