Lattice Boltzmann modeling for the coalescence between a free droplet in gases and a sessile droplet on wettable substrate with contact angle hysteresis

2017 ◽  
Vol 232 (3) ◽  
pp. 431-444 ◽  
Author(s):  
Lei Wang ◽  
Jianglong Sun
Keyword(s):  
Contact Angle ◽  
Kinetic Energy ◽  
Lattice Boltzmann ◽  
Capillary Wave ◽  
Contact Angle Hysteresis ◽  
Typical Characteristic ◽  
Ohnesorge Number ◽  
Sessile Droplet ◽  
Two Phase ◽  
Boltzmann Method

The coalescence between a free droplet and a sessile droplet on wettable substrate is numerically studied. The axisymmetric lattice Boltzmann method for two-phase flows is used in modeling. Here the contact angle hysteresis (prescribed by advancing angle [Formula: see text] and receding angle [Formula: see text]) is taken into account. The effects of Ohnesorge number ( Oh), contact angle and its hysteresis, and the radius of the free droplet on the coalescence dynamics are investigated in detail. The Oh numbers ranging from 0.02 to 0.15 here makes the radius of the liquid bridge r and the time t follow power law. Also, Oh has remarkable impact on the development of capillary wave and on the amount of kinetic energy released from coalescence. It is found that the curve of the wetting radius varying with time includes several plateau stages, which is a typical characteristic for the effect of contact angle hysteresis. The larger window of contact angle hysteresis would result in smaller steady wetting radius after coalescence. Compared with the existence of contact angle hysteresis, the absence of contact angle hysteresis makes the droplets system release more kinetic energy during the coalescence but the released kinetic energy decays more rapidly and soon reduces to zero. Oppositely, if the contact angle hysteresis exists, the released kinetic energy would oscillate for a period of time before approaching zero.

Lattice Boltzmann Modelling of Contact Angle and Hysteresis Under Homogeneous and Heterogeneous Dynamic Wetting Regime

2019 ◽  
Author(s):  
Nursultan Zhumatay ◽  
Bagdagul Dauyeshova ◽  
Desmond Adair ◽  
Ernesto Monaco ◽  
Luis Rojas-Solorzano
Keyword(s):  
Contact Angle ◽  
Numerical Modelling ◽  
Lattice Boltzmann ◽  
Contact Angle Hysteresis ◽  
Contact Point ◽  
Intermolecular Forces ◽  
Lattice Boltzmann Model ◽  
Complex Nature ◽  
Sessile Droplet ◽  
Static Conditions

Abstract The contact angle is a measurement of wettability of a solid surface resulting from molecular attraction or repulsion at the encounter point between a liquid-gas interface and a wall. To date, the determination of the contact angle is commonly performed experimentally with very limited numerical modelling, due to the complex nature of the intermolecular forces at the liquid-gas-solid contact point, even in static conditions. This investigation presents the numerical modelling of the contact angle in static and dynamic conditions on homogeneous and heterogeneous wetting regimes using the multiphase Shan-Chen Lattice Boltzmann Model (SC-LBM). The dynamics of the phenomenon is modelled firstly through a statically suspended droplet and secondly through a sessile droplet subject to the shear flow of air. The Wenzel and Cassie-Baxter states are well reproduced as the response to surface roughness homogeneity. Numerical results demonstrate the excellent suitability of the multiphase SC-LBM for this problem. Furthermore, contact-angle hysteresis is determined under the homogeneous wetting dynamic regime. Two different motion modes were observed during the investigation of the contact angle hysteresis.

scholarly journals Lattice Boltzmann simulation of liquid falling on horizontal rectangular pillar arrays

2021 ◽  
Vol 321 ◽  
pp. 01014
Author(s):  
Makoto Sugimoto ◽  
Tatsuya Miyazaki ◽  
Zelin Li ◽  
Masayuki Kaneda ◽  
Kazuhiko Suga
Keyword(s):  
Lattice Boltzmann ◽  
Three Dimensional ◽  
Phase Field Model ◽  
Flow Simulation ◽  
High Viscosity ◽  
Two Phase ◽  
Lattice Boltzmann Simulation ◽  
Pillar Arrays ◽  
Boltzmann Method ◽  
Behavior Characteristic

Stator coils of automobiles in operation generate heat and are cooled by a coolant poured from above. Since the behavior characteristic of the coolant poured on the coils is not clarified yet due to its complexity, the three-dimensional two-phase flow simulation is conducted. In this study, as a steppingstone to the simulation of the liquid falling on the actual coils, the coils are modelled with horizontal rectangular pillar arrays whose governing parameters can be easily changed. The two-phase flows are simulated using the lattice Boltzmann method and the phase-field model, and the effects of the governing parameters, such as the physical properties of the cooling liquid, the wettability, and the gap between the pillars, on the wetting area are investigated. The results show that the oil tends to spread across the pillars because of its high viscosity. Moreover, the liquid spreads quickly when the contact angle is small. In the case that the pillars are stacked, the wetting area of the inner pillars is larger than that of the exposed pillars.

A multi-component two-phase lattice Boltzmann method applied to a 1-D Fischer–Tropsch reactor

2012 ◽  
Vol 207-208 ◽  
pp. 587-595 ◽  
Author(s):  
M.R. Kamali ◽  
S. Sundaresan ◽  
H.E.A. Van den Akker ◽  
J.J.J. Gillissen
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Fischer Tropsch ◽  
Two Phase ◽  
Boltzmann Method
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