Detlef Lohse | University of Twente (original) (raw)
Papers by Detlef Lohse
Physics of Fluids, 2003
When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical c... more When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical container and shaken vertically, thin jets are seen to emerge from an airy cloud of grains, almost like protuberances from the corona of the sun. A quasi two-dimensional setup reveals the jet-formation process: The sand accumulates in ripples, and below
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Journal of Fluid Mechanics, 2009
The growth and collapse of a vapour bubble inside a microtube is studied both experimentally and ... more The growth and collapse of a vapour bubble inside a microtube is studied both experimentally and theoretically. The length of the bubble, and the velocity and acceleration of its interface, are obtained from a high-speed image recording (typically 1. 25× 105 fps) ...
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Physical Review Letters, 2015
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ACS nano, Jan 26, 2015
Nanoscale droplets on a substrate are of great interest because of their relevance for droplet-ba... more Nanoscale droplets on a substrate are of great interest because of their relevance for droplet-based technologies for light manipulation, lab-on-chip devices, miniaturised reactors, encapsulation and many others. In this work, we establish a basic principle for the symmetrical arrangement of surface nanodroplets during their growth out of oversaturated solution established through solvent exchange, which takes place under simple and controlled flow conditions. In our model system, nanodroplets nucleate at the rim of spherical cap microstructures on a substrate, as a pulse of oversaturation is supplied by a solvent exchange process. We find that, while growing, the nanodroplets self-organise into highly symmetric arrangements, with respect to position, size, and mutual distance. The angle between the neighbouring droplets is four times the ratio between the base radii of the droplets and the spherical caps. We show and explain how the nanodroplets acquire the symmetrical spatial arra...
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The Journal of chemical physics, Jan 21, 2015
The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still ... more The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still not understood. Insufficient knowledge of the interaction potentials and the lack of relevant experimental access to the growth process are to blame for this failure. Here, we study the growth of fractal nanostructures in a two-dimensional (2D) system, intercalated between mica and graphene. Based on our scanning tunneling spectroscopy data, we provide compelling evidence that these fractals are 2D ice. They grow while they are in material contact with the atmosphere at 20 °C and without significant thermal contact to the ambient. The growth is studied in situ, in real time and space at the nanoscale. We find that the growing 2D ice nanocrystals assume a fractal shape, which is conventionally attributed to Diffusion Limited Aggregation (DLA). However, DLA requires a low mass density mother phase, in contrast to the actual currently present high mass density mother phase. Latent heat effe...
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The Journal of chemical physics, Jan 28, 2015
We numerically study different forms of nanoscale gaseous domains on a model for rough surfaces. ... more We numerically study different forms of nanoscale gaseous domains on a model for rough surfaces. Our calculations based on the constrained lattice density functional theory show that the inter-connectivity of pores surrounded by neighboring nanoposts, which model the surface roughness, leads to the formation of stable microscopic Cassie states. We investigate the dependence of the stability of the micro-Cassie states on substrate roughness, fluid-solid interaction, and chemical potential and then address the differences between the origin of the micro-Cassie states and that of surface nanobubbles within similar models. Finally, we show that the micro-Cassie states share some features with experimentally observed micropancakes at solid-water interfaces.
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Proceedings of the National Academy of Sciences of the United States of America, Jan 9, 2015
Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high... more Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, laboratory-on-chip devices, and near-field imaging techniques. Oil nanodroplets can be produced on a solid-liquid interface in a simple step of solvent exchange in which a good solvent of oil is displaced by a poor solvent. In this work, we experimentally and theoretically investigate the formation of nanodroplets by the solvent exchange process under well-controlled flow conditions. We find significant effects from the flow rate and the flow geometry on the droplet size. We develop a theoretical framework to account for these effects. The main idea is that the droplet nuclei are exposed to an oil oversaturation pulse during the exchange process. The analysis shows that the volume of the nanodroplets increases with the Peclet number [Formula: see text] of the flow as [Formula: see text], which is in good agreement with our exper...
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Review of Scientific Instruments, 2015
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Op de wand van een bekerglas gevuld met kraanwater zullen na enige tijd luchtbelletjes verschijne... more Op de wand van een bekerglas gevuld met kraanwater zullen na enige tijd luchtbelletjes verschijnen. Een alledaags fenomeen waar weinig mensen vreemd van opkijken. Maar sinds enige jaren zijn er extreem kleine luchtbellen op oppervlakken gevonden die ...
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Physical review. E, Statistical, nonlinear, and soft matter physics, 2015
Surface nanobubbles are experimentally known to survive for days at hydrophobic surfaces immersed... more Surface nanobubbles are experimentally known to survive for days at hydrophobic surfaces immersed in gas-oversaturated water. This is different from bulk nanobubbles, which are pressed out by the Laplace pressure against any gas oversaturation and dissolve in submilliseconds, as derived by Epstein and Plesset [J. Chem. Phys. 18, 1505 (1950)]. Pinning of the contact line has been speculated to be the reason for the stability of the surface nanobubbles. Building on an exact result by Popov [Phys. Rev. E 71, 036313 (2005)] on coffee stain evaporation, here we confirm this speculation by an exact calculation for single surface nanobubbles. It is based only on (i) the diffusion equation, (ii) Laplace pressure, and (iii) Henry's equation, i.e., fluid dynamical equations which are all known to be valid down to the nanometer scale. The crucial parameter is the gas oversaturation ζ of the liquid. At the stable equilibrium, the gas overpressures due to this oversaturation and the Laplace ...
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Physics Letters A, 1994
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Physics, 2008
ABSTRACT
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Macromolecular Materials and Engineering, 2011
... Figure 2. Photograph of the conical hot-film probe (55R42, Dantec Inc., Denmark). The probe i... more ... Figure 2. Photograph of the conical hot-film probe (55R42, Dantec Inc., Denmark). The probe is aligned perpendicular to the flow, which is directed downwards. ... Fluids 2006, 18, 038103. [11] J. Martinez-Mercado, D. Chehata-Gomez, D. van Gils, C. Sun, D. Lohse, J. Fluid Mech. ...
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Solid State Phenomena, 2008
... Visualizing nano-scale bubbles with cavitation Bram Borkent 1, a , Nicolas Bremond 2 , Manish... more ... Visualizing nano-scale bubbles with cavitation Bram Borkent 1, a , Nicolas Bremond 2 , Manish Arora 1 , Claus-Dieter Ohl 1 and Detlef Lohse 1 1 Physics of Fluids, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands ...
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Physical Review Letters, 2015
Two-dimensional simulations of Rayleigh-Bénard convection at Ra=5×10^{10} show that vertical loga... more Two-dimensional simulations of Rayleigh-Bénard convection at Ra=5×10^{10} show that vertical logarithmic mean temperature profiles can be observed in regions of the boundary layer where thermal plumes are emitted. The profile is logarithmic only in these regions and not in the rest of the boundary layer where it is sheared by the large-scale wind and impacted by plumes. In addition, the logarithmic behavior is not visible in the horizontal average. The findings reveal that the temperature profiles are strongly connected to thermal plume emission, and they support a perception that parts of the boundary layer can be turbulent while others are not. The transition to the ultimate regime, in which the boundary layers are considered to be fully turbulent, can therefore be understood as a gradual increase in the fraction of the plume-emitting ("turbulent") regions of the boundary layer.
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Langmuir : the ACS journal of surfaces and colloids, Jan 26, 2014
Understanding the wettability of graphene is the crucial step toward the design and control of gr... more Understanding the wettability of graphene is the crucial step toward the design and control of graphene-based surface in contact with liquids. In this work, the static microwettability of a supported single layer graphene (SLG) immersed in water or alcoholic aqueous solutions is revealed by the morphological characterization of the polymerized interfacial femtoliter droplets. As expected, the contact angle of the femtoliter droplets on the SLG in water is in between that on the underlying silanized silicon and that on graphite (HOPG). However, the wettability of femtoliter droplets on the SLG demonstrates a unique dependence on the compositions of the surrounding liquid medium: Their contact angle on SLG becomes much larger than that on both graphite and on silanized silicon, once short-chain alcohol molecules are present in the surrounding medium. To account for this finding, we hypothesize two scenarios to rationalize the effect of alcohol on the microwettability on SLG. The under...
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ABSTRACT
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Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 2000
Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large en... more Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level Re(sat) can be calculated analytically; different regimes can be observed. For large enough Re we find Re(sat) approximately Af, but intermittency can modify this scaling law. We suggest an experimental realization of periodically kicked turbulence to study the different regimes we theoretically predict and thus to better understand the effect of forcing on fully developed turbulence.
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Physics of Fluids, 2003
When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical c... more When a 6-mm layer of fine sand with an average grain size of 40 µm is poured into a cylindrical container and shaken vertically, thin jets are seen to emerge from an airy cloud of grains, almost like protuberances from the corona of the sun. A quasi two-dimensional setup reveals the jet-formation process: The sand accumulates in ripples, and below
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
Journal of Fluid Mechanics, 2009
The growth and collapse of a vapour bubble inside a microtube is studied both experimentally and ... more The growth and collapse of a vapour bubble inside a microtube is studied both experimentally and theoretically. The length of the bubble, and the velocity and acceleration of its interface, are obtained from a high-speed image recording (typically 1. 25× 105 fps) ...
Bookmarks Related papers MentionsView impact
Physical Review Letters, 2015
Bookmarks Related papers MentionsView impact
ACS nano, Jan 26, 2015
Nanoscale droplets on a substrate are of great interest because of their relevance for droplet-ba... more Nanoscale droplets on a substrate are of great interest because of their relevance for droplet-based technologies for light manipulation, lab-on-chip devices, miniaturised reactors, encapsulation and many others. In this work, we establish a basic principle for the symmetrical arrangement of surface nanodroplets during their growth out of oversaturated solution established through solvent exchange, which takes place under simple and controlled flow conditions. In our model system, nanodroplets nucleate at the rim of spherical cap microstructures on a substrate, as a pulse of oversaturation is supplied by a solvent exchange process. We find that, while growing, the nanodroplets self-organise into highly symmetric arrangements, with respect to position, size, and mutual distance. The angle between the neighbouring droplets is four times the ratio between the base radii of the droplets and the spherical caps. We show and explain how the nanodroplets acquire the symmetrical spatial arra...
Bookmarks Related papers MentionsView impact
The Journal of chemical physics, Jan 21, 2015
The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still ... more The basic science responsible for the fascinating shapes of ice crystals and snowflakes is still not understood. Insufficient knowledge of the interaction potentials and the lack of relevant experimental access to the growth process are to blame for this failure. Here, we study the growth of fractal nanostructures in a two-dimensional (2D) system, intercalated between mica and graphene. Based on our scanning tunneling spectroscopy data, we provide compelling evidence that these fractals are 2D ice. They grow while they are in material contact with the atmosphere at 20 °C and without significant thermal contact to the ambient. The growth is studied in situ, in real time and space at the nanoscale. We find that the growing 2D ice nanocrystals assume a fractal shape, which is conventionally attributed to Diffusion Limited Aggregation (DLA). However, DLA requires a low mass density mother phase, in contrast to the actual currently present high mass density mother phase. Latent heat effe...
Bookmarks Related papers MentionsView impact
Bookmarks Related papers MentionsView impact
The Journal of chemical physics, Jan 28, 2015
We numerically study different forms of nanoscale gaseous domains on a model for rough surfaces. ... more We numerically study different forms of nanoscale gaseous domains on a model for rough surfaces. Our calculations based on the constrained lattice density functional theory show that the inter-connectivity of pores surrounded by neighboring nanoposts, which model the surface roughness, leads to the formation of stable microscopic Cassie states. We investigate the dependence of the stability of the micro-Cassie states on substrate roughness, fluid-solid interaction, and chemical potential and then address the differences between the origin of the micro-Cassie states and that of surface nanobubbles within similar models. Finally, we show that the micro-Cassie states share some features with experimentally observed micropancakes at solid-water interfaces.
Bookmarks Related papers MentionsView impact
Proceedings of the National Academy of Sciences of the United States of America, Jan 9, 2015
Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high... more Nanodroplets on a solid surface (i.e., surface nanodroplets) have practical implications for high-throughput chemical and biological analysis, lubrications, laboratory-on-chip devices, and near-field imaging techniques. Oil nanodroplets can be produced on a solid-liquid interface in a simple step of solvent exchange in which a good solvent of oil is displaced by a poor solvent. In this work, we experimentally and theoretically investigate the formation of nanodroplets by the solvent exchange process under well-controlled flow conditions. We find significant effects from the flow rate and the flow geometry on the droplet size. We develop a theoretical framework to account for these effects. The main idea is that the droplet nuclei are exposed to an oil oversaturation pulse during the exchange process. The analysis shows that the volume of the nanodroplets increases with the Peclet number [Formula: see text] of the flow as [Formula: see text], which is in good agreement with our exper...
Bookmarks Related papers MentionsView impact
Review of Scientific Instruments, 2015
Bookmarks Related papers MentionsView impact
Op de wand van een bekerglas gevuld met kraanwater zullen na enige tijd luchtbelletjes verschijne... more Op de wand van een bekerglas gevuld met kraanwater zullen na enige tijd luchtbelletjes verschijnen. Een alledaags fenomeen waar weinig mensen vreemd van opkijken. Maar sinds enige jaren zijn er extreem kleine luchtbellen op oppervlakken gevonden die ...
Bookmarks Related papers MentionsView impact
Physical review. E, Statistical, nonlinear, and soft matter physics, 2015
Surface nanobubbles are experimentally known to survive for days at hydrophobic surfaces immersed... more Surface nanobubbles are experimentally known to survive for days at hydrophobic surfaces immersed in gas-oversaturated water. This is different from bulk nanobubbles, which are pressed out by the Laplace pressure against any gas oversaturation and dissolve in submilliseconds, as derived by Epstein and Plesset [J. Chem. Phys. 18, 1505 (1950)]. Pinning of the contact line has been speculated to be the reason for the stability of the surface nanobubbles. Building on an exact result by Popov [Phys. Rev. E 71, 036313 (2005)] on coffee stain evaporation, here we confirm this speculation by an exact calculation for single surface nanobubbles. It is based only on (i) the diffusion equation, (ii) Laplace pressure, and (iii) Henry's equation, i.e., fluid dynamical equations which are all known to be valid down to the nanometer scale. The crucial parameter is the gas oversaturation ζ of the liquid. At the stable equilibrium, the gas overpressures due to this oversaturation and the Laplace ...
Bookmarks Related papers MentionsView impact
Physics Letters A, 1994
Bookmarks Related papers MentionsView impact
Physics, 2008
ABSTRACT
Bookmarks Related papers MentionsView impact
Macromolecular Materials and Engineering, 2011
... Figure 2. Photograph of the conical hot-film probe (55R42, Dantec Inc., Denmark). The probe i... more ... Figure 2. Photograph of the conical hot-film probe (55R42, Dantec Inc., Denmark). The probe is aligned perpendicular to the flow, which is directed downwards. ... Fluids 2006, 18, 038103. [11] J. Martinez-Mercado, D. Chehata-Gomez, D. van Gils, C. Sun, D. Lohse, J. Fluid Mech. ...
Bookmarks Related papers MentionsView impact
Solid State Phenomena, 2008
... Visualizing nano-scale bubbles with cavitation Bram Borkent 1, a , Nicolas Bremond 2 , Manish... more ... Visualizing nano-scale bubbles with cavitation Bram Borkent 1, a , Nicolas Bremond 2 , Manish Arora 1 , Claus-Dieter Ohl 1 and Detlef Lohse 1 1 Physics of Fluids, University of Twente, PO Box 217, 7500 AE Enschede, The Netherlands ...
Bookmarks Related papers MentionsView impact
Physical Review Letters, 2015
Two-dimensional simulations of Rayleigh-Bénard convection at Ra=5×10^{10} show that vertical loga... more Two-dimensional simulations of Rayleigh-Bénard convection at Ra=5×10^{10} show that vertical logarithmic mean temperature profiles can be observed in regions of the boundary layer where thermal plumes are emitted. The profile is logarithmic only in these regions and not in the rest of the boundary layer where it is sheared by the large-scale wind and impacted by plumes. In addition, the logarithmic behavior is not visible in the horizontal average. The findings reveal that the temperature profiles are strongly connected to thermal plume emission, and they support a perception that parts of the boundary layer can be turbulent while others are not. The transition to the ultimate regime, in which the boundary layers are considered to be fully turbulent, can therefore be understood as a gradual increase in the fraction of the plume-emitting ("turbulent") regions of the boundary layer.
Bookmarks Related papers MentionsView impact
Langmuir : the ACS journal of surfaces and colloids, Jan 26, 2014
Understanding the wettability of graphene is the crucial step toward the design and control of gr... more Understanding the wettability of graphene is the crucial step toward the design and control of graphene-based surface in contact with liquids. In this work, the static microwettability of a supported single layer graphene (SLG) immersed in water or alcoholic aqueous solutions is revealed by the morphological characterization of the polymerized interfacial femtoliter droplets. As expected, the contact angle of the femtoliter droplets on the SLG in water is in between that on the underlying silanized silicon and that on graphite (HOPG). However, the wettability of femtoliter droplets on the SLG demonstrates a unique dependence on the compositions of the surrounding liquid medium: Their contact angle on SLG becomes much larger than that on both graphite and on silanized silicon, once short-chain alcohol molecules are present in the surrounding medium. To account for this finding, we hypothesize two scenarios to rationalize the effect of alcohol on the microwettability on SLG. The under...
Bookmarks Related papers MentionsView impact
ABSTRACT
Bookmarks Related papers MentionsView impact
Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics, 2000
Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large en... more Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level Re(sat) can be calculated analytically; different regimes can be observed. For large enough Re we find Re(sat) approximately Af, but intermittency can modify this scaling law. We suggest an experimental realization of periodically kicked turbulence to study the different regimes we theoretically predict and thus to better understand the effect of forcing on fully developed turbulence.
Bookmarks Related papers MentionsView impact