Numerical simulation of pulmonary airway reopening by the multiphase lattice Boltzmann method

He, Bing; Qin, Chunyan; Chen, Wenbo; Wen, Binghai

doi:10.1016/j.camwa.2022.01.013

Cited by 6 publications

(5 citation statements)

References 46 publications

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“…At ideal gas pressure, the nonideal force can be calculated based on the overpressure part [ 23 , 42 , 43 , 44 , 51 ]:

From Equations ( 20 ) and ( 21 ), it is easy to obtain the formula for calculating the nonideal force based on the chemical potential, which contains only the density and the free energy density:

…”

Section: Theoretical Methods and Numerical Modelmentioning

confidence: 99%

Movable and Focus-Tunable Lens Based on Electrically Controllable Liquid: A Lattice Boltzmann Study

Wang

Zhuang

Qin

et al. 2022

Entropy

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Adjusting the focal length by changing the liquid interface of the liquid lens has become a potential method. In this paper, the lattice-Boltzmann-electrodynamic (LB-ED) method is used to numerically investigate the zooming process of a movable and focus-tunable electrowetting-on-dielectrics (EWOD) liquid lens by combining the LBM chemical potential model and the electrodynamic model. The LB method is used to solve the Navier–Stokes equation, and the Poisson–Boltzmann (PB) equation is introduced to solve the electric field distribution. The experimental results are consistent with the theoretical results of the Lippmann–Young equation. Through the simulation of a liquid lens zoom driven by EWOD, it is found that the lens changes from a convex lens to a concave lens with the voltage increases. The focal length change rate in the convex lens stage gradually increases with voltage. In the concave lens stage, the focal length change rate is opposite to that in the convex lens stage. During the zooming process, the low-viscosity liquid exhibits oscillation, and the high-viscosity liquid appears as overdamping. Additionally, methods were proposed to accelerate lens stabilization at low and high viscosities, achieving speed improvements of about 30% and 50%, respectively. Simulations of lens motion at different viscosities demonstrate that higher-viscosity liquids require higher voltages to achieve the same movement speed.

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“…At ideal gas pressure, the nonideal force can be calculated based on the overpressure part [ 23 , 42 , 43 , 44 , 51 ]:

From Equations ( 20 ) and ( 21 ), it is easy to obtain the formula for calculating the nonideal force based on the chemical potential, which contains only the density and the free energy density:

…”

Section: Theoretical Methods and Numerical Modelmentioning

confidence: 99%

Movable and Focus-Tunable Lens Based on Electrically Controllable Liquid: A Lattice Boltzmann Study

Wang

Zhuang

Qin

et al. 2022

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“…The multi-scale multiphase DFKT is expected to contribute to the area of materials science for energy-environment applications (Succi et al 2020) and medical purposes (Xu et al 2018b;Li et al 2022). For instance, it may help us: to understand the non-equilibrium transport processes of multiphase flow in proton exchange membrane fuel cells for obtaining better performance, and lower cost, emission and noise (Chen, Kang & Tao 2021a); to investigate the non-equilibrium nucleate boiling mechanism and design suitable surface structures for enhancing nucleate boiling heat transfer efficiency (Biferale et al 2012;Li et al , 2020Fei et al 2020); to optimize heat source location (Dai et al 2020) and improve the latent heat thermal energy storage rate (Ren 2019;Tian et al 2022); to conduct mesoscale simulations of blood flow (Dupin, Halliday & Care 2006;Yan et al 2012), and generation, transmission and diffusion of bioaerosols (He et al 2022).…”

Section: Discrete Formulation Of Density Functional Kinetic Theorymentioning

confidence: 99%

Discrete Boltzmann multi-scale modelling of non-equilibrium multiphase flows

Gan

Xu²,

Lai³

et al. 2022

J. Fluid Mech.

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The aim of this paper is twofold: the first aim is to formulate and validate a multi-scale discrete Boltzmann method (DBM) based on density functional kinetic theory for thermal multiphase flow systems, ranging from continuum to transition flow regime; the second aim is to present some new insights into the thermo-hydrodynamic non-equilibrium (THNE) effects in the phase separation process. Methodologically, for bulk flow, DBM includes three main pillars: (i) the determination of the fewest kinetic moment relations, which are required by the description of significant THNE effects beyond the realm of continuum fluid mechanics; (ii) the construction of an appropriate discrete equilibrium distribution function recovering all the desired kinetic moments; (iii) the detection, description, presentation and analysis of THNE based on the moments of the non-equilibrium distribution ( $f-f^{(eq)}$ ). The incorporation of appropriate additional higher-order thermodynamic kinetic moments considerably extends the DBM's capability of handling larger values of the liquid–vapour density ratio, curbing spurious currents, and ensuring mass/momentum/energy conservation. Compared with the DBM with only first-order THNE (Gan et al., Soft Matt., vol. 11 (26), 2015, pp. 5336–5345), the model retrieves kinetic moments beyond the third-order super-Burnett level, and is accurate for weak, moderate and strong THNE cases even when the local Knudsen number exceeds $1/3$ . Physically, the ending point of the linear relation between THNE and the concerned physical parameter provides a distinct criterion to identify whether the system is near or far from equilibrium. Besides, the surface tension suppresses the local THNE around the interface, but expands the THNE range and strengthens the THNE intensity away from the interface through interface smoothing and widening.

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“…As an example of use, the state of the art has proposed studies to simulate the flow of a fluid, the authors create two neural networks, one for the speed of the fluid and the other for the permeability [36][37][38][39]:…”

Section: Related Workmentioning

confidence: 99%

“…By creating this neural network model for the 2 variables in their temporal and spatial evolution, they also integrate physical constraints ensuring mass conservation. These physical constraints can be integrated into the loss function [40][41][42][43].…”

Section: Related Workmentioning

confidence: 99%

Optimization of the Creation of a Training Set for the Calibration of a Model Reproducing the Vibration Behavior of an Overhead Line Conductor

Amroun,

Hafid,

Ammi

2022

IJICS

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One of the applications that machine learning can offer to the world of Engineering and Fluid Mechanics in particular is the calibration of models making it possible to approximate the representation of a particular phenomenon. Indeed, the computational cost generated by some fluid mechanics models pushes scientists to use other models close to the original models but less computationally intensive in order to facilitate their handling. Among the different approaches used: machine learning coupled with some optimization methods and algorithms in order to reduce the computation cost induced. This paper proposes a new framework called OPTI-ENS: a new flexible, optimized and improved method, to calibrate a physical model, called the wake oscillator (WO), which simulates the vibratory behaviors of overhead line conductors. An approximation of a heavy and complex model called the strip theory (ST) model. OPTI-ENS is composed of an ensemble machine learning algorithm (ENS) and an optimization algorithm of the WO model so that the WO model can generate the adequate training data as input to the ENS model. ENS model will therefore take as input the data from the WO model and output the data from the ST model. As a benchmark, a series of Machine learning models have been implemented and tested. The OPTI-ENS algorithm was retained with a best Coefficient of determination (R2 Score) of almost 0.7 and a Root mean square error (RMSE) of 7.57e-09. In addition, this model is approximately 170 times faster (in terms of calculation time) than an ENS model without optimization of the generation of training data by the WO model. This type of approach therefore makes it possible to calibrate the WO model so that simulations of the behavior of overhead line conductors are carried out only with the WO model.

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Numerical simulation of pulmonary airway reopening by the multiphase lattice Boltzmann method

Cited by 6 publications

References 46 publications

Movable and Focus-Tunable Lens Based on Electrically Controllable Liquid: A Lattice Boltzmann Study

Movable and Focus-Tunable Lens Based on Electrically Controllable Liquid: A Lattice Boltzmann Study

Discrete Boltzmann multi-scale modelling of non-equilibrium multiphase flows

Optimization of the Creation of a Training Set for the Calibration of a Model Reproducing the Vibration Behavior of an Overhead Line Conductor

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