Publications
30 results found
Ahmed H, Biancofiore L, 2023, Modeling polymeric lubricants with non-linear stress constitutive relations, JOURNAL OF NON-NEWTONIAN FLUID MECHANICS, Vol: 321, ISSN: 0377-0257
Bronte Ciriza D, Callegari A, Donato MG, et al., 2023, Optically Driven Janus Microengine with Full Orbital Motion Control., ACS Photonics, Vol: 10, Pages: 3223-3232, ISSN: 2330-4022
Microengines have shown promise for a variety of applications in nanotechnology, microfluidics, and nanomedicine, including targeted drug delivery, microscale pumping, and environmental remediation. However, achieving precise control over their dynamics remains a significant challenge. In this study, we introduce a microengine that exploits both optical and thermal effects to achieve a high degree of controllability. We find that in the presence of a strongly focused light beam, a gold-silica Janus particle becomes confined at the stationary point where the optical and thermal forces balance. By using circularly polarized light, we can transfer angular momentum to the particle, breaking the symmetry between the two forces and resulting in a tangential force that drives directed orbital motion. We can simultaneously control the velocity and direction of rotation of the particle changing the ellipticity of the incoming light beam while tuning the radius of the orbit with laser power. Our experimental results are validated using a geometrical optics phenomenological model that considers the optical force, the absorption of optical power, and the resulting heating of the particle. The demonstrated enhanced flexibility in the control of microengines opens up new possibilities for their utilization in a wide range of applications, including microscale transport, sensing, and actuation.
Bayram AG, Schwarzendahl FJ, Lowen H, et al., 2023, Motility-induced shear thickening in dense colloidal suspensions, SOFT MATTER, Vol: 19, Pages: 4571-4578, ISSN: 1744-683X
Mohamed H, Sesterhenn J, Biancofiore L, 2023, The effect of side walls on the stability of falling films, JOURNAL OF FLUID MECHANICS, Vol: 964, ISSN: 0022-1120
Cam MY, Giacopini M, Dini D, et al., 2023, A numerical algorithm to model wall slip and cavitation in two-dimensional hydrodynamically lubricated contacts, TRIBOLOGY INTERNATIONAL, Vol: 184, ISSN: 0301-679X
Ahmed H, Biancofiore L, 2022, A modified viscosity approach for shear thinning lubricants, PHYSICS OF FLUIDS, Vol: 34, ISSN: 1070-6631
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- Citations: 2
Mohamed OAA, Dallaston MC, Biancofiore L, 2021, Spatiotemporal evolution of evaporating liquid films sheared by a gas, PHYSICAL REVIEW FLUIDS, Vol: 6, ISSN: 2469-990X
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- Citations: 1
Gamaniel SS, Dini D, Biancofiore L, 2021, The effect of fluid viscoelasticity in lubricated contacts in the presence of cavitation, Tribology International, Vol: 160, ISSN: 0301-679X
In this work we study the influence of fluid viscoelasticity on the performance of lubricated contacts in the presence of cavitation. Several studies of viscoelastic lubricants have been carried out, but none of them have considered the possibility of the presence of cavitation. To describe the effect of viscoelasticity, we use the Oldroyd-B model. By assuming that the product between ϵ, i.e. the ratio between vertical and horizontal length scales, and the Weissenberg number (Wi), i.e. the ratio between polymer relaxation time and flow time scale, is small, we can linearise the viscoelastic thin film equations, following the approach pioneered by "Tichy, J., 1996, Non-Newtonian lubrication with the convected Maxwell model." Consequently, the zeroth-order in ϵWi corresponds to a Reynolds equation modified to describe also the film cavitation through the mass-conserving Elrod-Adams model. We consider the flow of viscoelastic lubricants using: (i) a cosine profile representing a journal bearing unwrapped geometry, and (ii) a pocketed profile to model a textured surface in lubricated contacts. The introduction of viscoelasticity decreases the length of cavitated region in the cosine profile due to the increasing pressure distribution within the film. Consequently, the load carrying capacity increases with Wi by up to 50% in the most favorable condition, confirming the beneficial influence of the polymers in bearings. On the other hand for the pocketed profile, results show that the load can increase or decrease at higher Wi depending on the texture position in the contact. The squeeze flow problem between two plates is also modeled for viscoelastic lubricants considering an oscillating top surface. For this configuration a load reduction is observed with increasing Wi due to the additional time needed to reform the film at high Wi. Furthermore, if viscoelastic effects increase, the cavitation region widens until reaching a value of Wi for which a full-film ref
Ahmed H, Biancofiore L, 2021, A new approach for modeling viscoelastic thin film lubrication, JOURNAL OF NON-NEWTONIAN FLUID MECHANICS, Vol: 292, ISSN: 0377-0257
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- Citations: 10
Zaqarashvili T, Albekioni M, Ballester JL, et al., 2021, Rossby Waves in Astrophysics, SPACE SCIENCE REVIEWS, Vol: 217, ISSN: 0038-6308
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- Citations: 35
Callegari A, Mousavi SM, Kasianiuk I, et al., 2021, Clustering of Janus particles in an optical potential driven by hydrodynamic fluxes, ISSN: 0277-786X
Self-organisation is driven by the interactions between the individual components of a system mediated by the environment, and is one of the most important strategies used by many biological systems to develop complex and functional structures. Furthermore, biologically-inspired self-organisation offers opportunities to develop the next generation of materials and devices for electronics, photonics and nanotechnology. In this work, we demonstrate experimentally that a system of Janus particles (silica microspheres half-coated with gold) aggregates into clusters in the presence of a Gaussian optical potential and disaggregates when the optical potential is switched off. We show that the underlying mechanism is the existence of a hydrodynamic flow induced by a temperature gradient generated by the light absorption at the metallic patches on the Janus particles. We also perform simulations, which agree well with the experiments and whose results permit us to clarify the underlying mechanism. The possibility of hydrodynamic-flux-induced reversible clustering may have applications in the fields of drug delivery, cargo transport, bioremediation and biopatterning.
Callegari A, Mousavi SM, Kasianiuk I, et al., 2021, Clustering of Janus particles under the effect of optical forces driven by hydrodynamic fluxes
Hydrodynamic fluxes generated by Janus particles in an optical potential drive reversible clustering of colloids.
Mohamed H, Biancofiore L, 2020, Linear stability analysis of evaporating falling liquid films, INTERNATIONAL JOURNAL OF MULTIPHASE FLOW, Vol: 130, ISSN: 0301-9322
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- Citations: 3
Biancofiore L, Giacopini M, Dini D, 2019, Interplay between wall slip and cavitation: A complementary variable approach, Tribology International, Vol: 137, Pages: 324-339, ISSN: 0301-679X
In this work a stable and reliable numerical model based on complementary variables is developed to study lubricated contacts characterised by slip at one or both surfaces and in the presence of cavitation. This model can be used to predict surface behaviour when cavitation induced by e.g. the presence of surface texture, slip, or a combination of the two is encountered, with varying surface parameters. For this purpose, two different algorithms are coupled to predict the formation of cavitation, through a mass-conserving formulation, and the presence of slip at the wall. The possible slippage is described by a limiting shear criterion formulated using a Tresca model. To show the flexibility of our model, several bearing geometries have been analysed, such as a twin parabolic slider, a cosine profile used to mimic a bearing, and a pocketed slider bearing employed to study the effect of surface texture. We observe that the lubrication performance (i.e. low friction coefficient) can be improved by using materials that promote slippage at the moving wall. The location of the slippage region can be optimised to find the lowest value of friction coefficient. Our theoretical developments and numerical implementation are shown to produce useful guidelines to improve and optimise the design of textured superoleophobic surfaces in the presence of lubricated contacts.
Mousavi SM, Kasianiuk I, Kasyanyuk D, et al., 2019, Clustering of Janus particles in an optical potential driven by hydrodynamic fluxes, SOFT MATTER, Vol: 15, Pages: 5748-5759, ISSN: 1744-683X
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- Citations: 13
Biancofiore L, Umurhan OM, 2019, Linear and nonlinear stability of a quasigeostrophic mixing layer subject to a uniform background shear, PHYSICAL REVIEW FLUIDS, Vol: 4, ISSN: 2469-990X
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- Citations: 1
Schmidt F, Magazzu A, Callegari A, et al., 2018, Microscopic Engine Powered by Critical Demixing, PHYSICAL REVIEW LETTERS, Vol: 120, ISSN: 0031-9007
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- Citations: 43
Schmidt F, Magazzù A, Callegari A, et al., 2018, A critical microscopic engine in an optical tweezers
An optically trapped absorbing microsphere in a sub-critical mixture rotates around the optical trap thanks to diffusiophoretic propulsion, which can be controlled by adjusting the optical power, the temperature, and the criticality of the mixture.
Biancofiore L, Heifetz E, Hoepffner J, et al., 2017, Understanding the destabilizing role for surface tension in planar shear flows in terms of wave interaction, PHYSICAL REVIEW FLUIDS, Vol: 2, ISSN: 2469-990X
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- Citations: 8
Biancofiore L, Brandt L, Zaki TA, 2017, Streak instability in viscoelastic Couette flow, PHYSICAL REVIEW FLUIDS, Vol: 2, ISSN: 2469-990X
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- Citations: 18
Schmidt F, Magazzù A, Callegari A, et al., 2017, Microscopic engine powered by critical demixing
We propose a new type of engine that is powered by the local, reversible demixing of a critical binary liquid. A microscopic particle is optically trapped and performs revolutions due to the emergence of diffusiophoresis.
Biancofiore L, Gallaire F, Heifetz E, 2015, Interaction between counterpropagating Rossby waves and capillary waves in planar shear flows, PHYSICS OF FLUIDS, Vol: 27, ISSN: 1070-6631
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- Citations: 17
Biancofiore L, Gallaire F, Laure P, et al., 2014, Direct numerical simulations of two-phase immiscible wakes, FLUID DYNAMICS RESEARCH, Vol: 46, ISSN: 0169-5983
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- Citations: 7
Biancofiore L, 2014, Crossover between two- and three-dimensional turbulence in spatial mixing layers, JOURNAL OF FLUID MECHANICS, Vol: 745, Pages: 164-179, ISSN: 0022-1120
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- Citations: 12
Biancofiore L, Gallaire F, 2012, Counterpropagating Rossby waves in confined plane wakes, PHYSICS OF FLUIDS, Vol: 24, ISSN: 1070-6631
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- Citations: 10
Biancofiore L, Gallaire F, Pasquetti R, 2012, Influence of confinement on obstacle-free turbulent wakes, Computers & Fluids, Vol: 58, Pages: 27-44, ISSN: 0045-7930
Biancofiore L, Gallaire F, Pasquetti R, 2011, Large eddy simulations of confined turbulent wake flows, Journal of Physics: Conference Series, Vol: 318, Pages: 042044-042044
Biancofiore L, Gallaire F, Pasquetti R, 2011, Influence of confinement on a two-dimensional wake, JOURNAL OF FLUID MECHANICS, Vol: 688, Pages: 297-320, ISSN: 0022-1120
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- Citations: 17
Biancofiore L, Gallaire F, 2011, The influence of shear layer thickness on the stability of confined two-dimensional wakes, PHYSICS OF FLUIDS, Vol: 23, ISSN: 1070-6631
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- Citations: 15
Biancofiore L, Gallaire F, 2010, Influence of confinement on temporal stability of plane jets and wakes, PHYSICS OF FLUIDS, Vol: 22, ISSN: 1070-6631
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- Citations: 9
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