scholarly journals Regimes of motion of magnetocapillary swimmers

2021 ◽  
Vol 44 (4) ◽  
Author(s):  
Alexander Sukhov ◽  
Maxime Hubert ◽  
Galien Grosjean ◽  
Oleg Trosman ◽  
Sebastian Ziegler ◽  
...  
Keyword(s):  
Surface Tension ◽  
Lattice Boltzmann Method ◽  
Magnetic Moment ◽  
Lattice Boltzmann ◽  
Self Assembly ◽  
Maximum Velocity ◽  
The Self ◽  
Magnetic Contribution ◽  
Magnetic Forces ◽  
Boltzmann Method

Abstract The dynamics of a triangular magnetocapillary swimmer is studied using the lattice Boltzmann method. We extend on our previous work, which deals with the self-assembly and a specific type of the swimmer motion characterized by the swimmer’s maximum velocity centred around the particle’s inverse viscous time. Here, we identify additional regimes of motion. First, modifying the ratio of surface tension and magnetic forces allows to study the swimmer propagation in the regime of significantly lower frequencies mainly defined by the strength of the magnetocapillary potential. Second, introducing a constant magnetic contribution in each of the particles in addition to their magnetic moment induced by external fields leads to another regime characterized by strong in-plane swimmer reorientations that resemble experimental observations. Graphic Abstract

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

Open Physics ◽  
2016 ◽  
Vol 14 (1) ◽  
pp. 483-491 ◽  
Author(s):  
Wen-Kai Ge ◽  
Gui Lu ◽  
Xin Xu ◽  
Xiao-Dong Wang
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Droplet Spreading ◽  
Small Surface ◽  
Pore Sizes ◽  
Fluid Properties ◽  
Boltzmann Method ◽  
Porous Substrates

AbstractThe 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 surfacewettability 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 tension, leading to a smaller droplet lifetime. The goals of this study are to provide methods to manipulate the spreading and permeation separately, which are of practical interest in many industrial applications.

Verification of surface tension in the parallel free surface lattice Boltzmann method in waLBerla

2011 ◽  
Vol 45 (1) ◽  
pp. 177-186 ◽  
Author(s):  
Stefan Donath ◽  
Klaus Mecke ◽  
Swapna Rabha ◽  
Vivek Buwa ◽  
Ulrich Rüde
Keyword(s):  
Surface Tension ◽  
Free Surface ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Surface Lattice ◽  
Boltzmann Method

Simulation of Droplet Flows Using Lattice Boltzmann Method

2008 ◽  
Author(s):  
Amit Gupta ◽  
Ranganathan Kumar
Keyword(s):  
Surface Tension ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Potential Method ◽  
Time Interval ◽  
Short Time Interval ◽  
Impact Surface ◽  
Spread Factor ◽  
Boltzmann Method ◽  
The Impact

In this work, the mesoscale approach of two-dimensional lattice Boltzmann method (LBM) has been employed to study droplet collision with a dry wall. The impact of drops with solid walls is simulated by using the pseudo-potential method of LBM. Simulations have been conducted for 2<We<162, and it is shown that the maximum spreading of the drop on the solid surface depends on the surrounding density, velocity of impact, surface tension, and the surface wetting characteristics. For a short time interval right after the impact the spreading diameter is shown to follow a parabolic dependence with time. The spread factor is seen to be higher as the Weber number increases. Under certain conditions when the drop has a high impact velocity and/or low surface tension, the kinetic energy of impact dominates over the dissipation and surface energy, leading to breakup of the drop into smaller drops. This breakup is shown to depend upon the wetting/non-wetting nature of the surface used. The spread factor is found to be a maximum at the time of breakup.

Flow Behaviour Around Square and Circular Obstacles in 2D and 3D Configurations Using Lattice Boltzmann Method

2014 ◽  
Author(s):  
Wafik Abassi ◽  
Fethi Aloui ◽  
Sassi Ben Nasrallah ◽  
Laurent Keirsbulck ◽  
Jack Legrand
Keyword(s):  
Lattice Boltzmann Method ◽  
Cross Section ◽  
Vortex Shedding ◽  
Lattice Boltzmann ◽  
Flow Behavior ◽  
Circular Cross Section ◽  
Practical Interest ◽  
Maximum Velocity ◽  
Boltzmann Method ◽  
2D And 3D

The investigation of wakes of bluff bodies in a channel is still relevant despite the large number of works devoted on it, in both experimental and numerical studies. This attractiveness is mainly due to its related applications and practical interest in varied engineering fields. The understanding of dynamic flow behavior and the topology of the instability structures occurring in the wake is essential in order to optimize the obstacle shape according to the desired objectives. A confined laminar flow around a square and a circle, placed in a channel is numerically investigated in this work using Lattice Boltzmann method. The study is then extended to 3D computations with horizontal cylinder within a square then a circular cross-section mounted inside a rectangular duct. The Reynolds number (Re), based on the maximum velocity and the cross-section height varies between 50 and 120 and the blockage ratio is r=1/3. This geometry is representative of a passive method to enhance mixing in the laminar channel flow. LBM was built up on the D2Q9 and D3Q19 model for respectively 2D and 3D computations. The single relaxation time approach called the lattice-BGK method was adopted. The topology of the vortex-shedding phenomena and wake behavior according the Reynolds numbers, for both geometries of the obstacle are focused. The effect of wall confinement on the flow transition to the vortex shedding regime is discussed. Velocity profiles and integral parameters such as recirculation length and Strouhal number were investigated. The numerical results are supported by literatures works results for the same configuration showing the performance of LBM as numerical tools simulation for such kind of flows.

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