Droplet spreading on a porous surface: A lattice Boltzmann study

Frank, Xavier; Perré, Patrick

doi:10.1063/1.3701996

Cited by 57 publications

(54 citation statements)

References 40 publications

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“…The wettability of porous substrates has been studied in previous works [19,20,[23][24][25], however, among which, the substrate surface and the inside pores have unique wettability. To manipulate the spreading and the permeating time scale, we design hybrid wettability characteristics on the substrate surface and the inside pores, for example, hydrophobic surface and hydrophilic inside pores or hydrophilic surface and hydrophilic inside pores.…”

Section: Effects Of Substrate Propertiesmentioning

confidence: 99%

“…to study the process of droplets impinging, spreading, and permeating porous substrates. Frank et al [24,25] studied the spreading laws of the droplet inertia-controlled stage by changing the wettability and porosity using a lattice Boltzmann method.…”

Section: Introductionmentioning

confidence: 99%

“…The others [14,15,20,21,24,25] studied the spreading and permeating integrally. The separate and competitive mechanisms of the spreading and permeation processes are still unclear, which motivates the present study.…”

Section: Introductionmentioning

confidence: 99%

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Droplet spreading and permeating on the hybrid-wettability porous substrates: a lattice Boltzmann method study

Wenkai

et al. 2016

Open Physics

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Abstract:The spreading and permeation of droplets on porous substrates is a fundamental process in a variety of applications, such as coating, dyeing, and printing. The spreading and permeating usually occur synchronously but play different roles in the practical applications. The mechanisms of the competition between spreading and permeation is significant but still unclear. A lattice Boltzmann method is used to study the spreading and permeation of droplets on hybrid-wettability porous substrates, with different wettability on the surface and the inside pores. The competition between the spreading and the permeation processes is studied in this work from the effects of the substrate and the fluid properties, including the substrate wettability, the porous parameters, as well as the fluid surface tension and viscosity. The results show that increasing the surface wettability and the porosity contact angle both inhibit the spreading and the permeation processes. When the inside porosity contact angle is larger than 90 ∘ (hydrophobic), the permeation process does not occur. The droplets suspend on substrates with Cassie state. The droplets are more easily to permeate into substrates with a small inside porosity contact angle (hydrophilic), as well as large pore sizes. Otherwise, the droplets are more easily to spread on substrate surfaces with small surface contact angle (hydrophilic) and smaller pore sizes. The competition between droplet spreading and permeation is also related to the fluid properties. The permeation process is enhanced by increasing of surface

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Section: Effects Of Substrate Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Droplet spreading and permeating on the hybrid-wettability porous substrates: a lattice Boltzmann method study

Wenkai

et al. 2016

Open Physics

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“…It is also worth mentioning that sphere packings represent real systems in chromatography 24 and chemical engineering. 25 Popularity of the lattice Boltzmann method [26][27][28][29] as a flow solver can be attributed to its acceptable accuracy while using the bounce-back (BB) boundary condition, 9,30 for which the lattice populations facing a solid voxel are reflected back from it. Simplicity, locality, and robustness of BB made it attractive among other boundary rules.…”

Section: Introductionmentioning

confidence: 99%

Behavior of numerical error in pore-scale lattice Boltzmann simulations with simple bounce-back rule: Analysis and highly accurate extrapolation

Khirevich

Patzek

2018

Physics of Fluids

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We perform the viscosity-independent Stokes flow simulations in regular sphere packings using the two-relaxation-times (TRT) lattice Boltzmann method (LBM) with the simple bounce-back (BB) rule. Our special discretization procedure reduces the scatter in integral quantities, such as drag force, and quantifies the solution convergence error. We assume transition to linear (−1) convergence rate for different sets of TRT parameters and use this assumption to provide a simple extrapolation scheme. After establishing the accurate reference values of drag for a wide range of porosities, 0.26–0.78, we show a ten-fold decrease in the drag error using the suggested extrapolations. This error decrease allows the simple LBM/BB scheme to reach an accuracy of the high-order interpolated boundary schemes. The suggested extrapolation approach is straightforward to apply in porous media, whose pore space can be discretized at several resolutions.

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“…In [16] three-dimensional simulations were carried out to study the effect of impact velocity and surface roughness on the spreading of droplets on to a substrate consisting of randomly placed and orientated freely penetrating disks using the lattice-Boltzmann method. The same methodology was used in [17] to simulate the pore-level droplet spreading on a porous surface and investigated the power-law time-evolution of the wetted zone radius. The present study attempts to numerically analyse the characteristics of a droplet interacting with a real porous surface, using a 3D porous media that is presented in [18].…”

Section: Introductionmentioning

confidence: 99%

Simulation of droplet spreading on micro-CT reconstructed 3D real porous media using the volume-of-fluid method

Aboukhedr

Mitroglou²,

Georgoulas

et al. 2017

Proceedings ILASS–Europe 2017. 28th Conference on Liquid Atomization and Spray Systems

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Droplet impact on porous media has a broad range of applications such as material processing, drug delivery and ink injection etc. The simulation studies of such processes are rather limited. To represent the spreading and absorption process of the droplet on porous materials, robust numerical schemes capable of accurately representing wettability as well as capillary effects need to be established. The current work, presents one of the first studies of droplet impact on a real porous media geometry model extracted from a micro-CT scan. The process involves processing of CT image and subsequent threshold based on the structures segmentation. The porous geometry is extracted in the form of a STL (STereoLithography) model, which, with the aid of dedicated software like ANSA and SnappyHexMesh, is converted to an unstructured mesh for successful discretization of the flow domain. The solution algorithm is developed within the open source CFD toolbox OpenFOAM. The numerical framework to track the droplet interface during the impact and the absorption phases is based on previous work [1,2]. The volume-of-fluid (VOF) method is used to capture the location of the interface, combined with additional sharpening and smoothing algorithms to minimise spurious velocities developed at the capillary dominated part of the phenomenon (droplet recession and penetration). A systematic variation of the main factors that affect this process are considered, i.e. wettability, porous size, impact velocity. To investigate the influence of porous structures on droplet spreading, the average porosity of the media is varied between 18.5% and 23.3% . From these numerical experiments, we can conclude that the droplet imbibition mainly depends on the porous wettability and secondly that the recoiling phase can be observed in the hydrophobic case but not in the hydrophilic case. Keywords; Droplet Spreading, Droplet Absorption, Porous media, 3D micro-Topography, VOF Introduction Micro-scale fluid phenomena are involved in various applications and research areas [3]. Understanding the behaviour of droplet spreading on porous media is important for a variety of industrial applications, such as ink jet printing, raindrops on textile, spray paint on wood, 3D-printing, penetration of rain drops into building walls, needle less injection, coating of porous materials, irrigation, cooling of electronic devices etc. Droplet spreading on solid flat surfaces has been the subject of numerous experimental and numerical studies over the last few decades [5,6]. However, droplet impact on porous media is still far from being understood. Studies of such micro-scale fluid phenomena need careful and combined consideration of droplet dynamics and porous media characteristics. Generally, this phenomenon is controlled by two main counter-acting processes: droplet spreading on porous surfaces and imbibition inside the porous media [8]. As the droplet spreads on the surface it also fills the voids of the porous material due to capillary action. The spreading be...

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Droplet spreading on a porous surface: A lattice Boltzmann study

Cited by 57 publications

References 40 publications

Droplet spreading and permeating on the hybrid-wettability porous substrates: a lattice Boltzmann method study

Droplet spreading and permeating on the hybrid-wettability porous substrates: a lattice Boltzmann method study

Behavior of numerical error in pore-scale lattice Boltzmann simulations with simple bounce-back rule: Analysis and highly accurate extrapolation

Simulation of droplet spreading on micro-CT reconstructed 3D real porous media using the volume-of-fluid method

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