Feasibility Study of Different Pseudopotential Multiphase Lattice Boltzmann Methods for Dendritic Solidification

2017 ◽  
Author(s):  
Seyed Amin Nabavizadeh ◽  
Mohsen Eshraghi ◽  
Sergio D. Felicelli
Keyword(s):  
Mechanical Properties ◽  
Lattice Boltzmann ◽  
Multiphase Model ◽  
Dendritic Solidification ◽  
Middle Range ◽  
Proposed Model ◽  
Exact Difference ◽  
Negative Effect ◽  
To Come ◽  
Boltzmann Method

The formation of porosity and bubbles during solidification in manufacturing processes like casting or welding of metals has a negative effect on the mechanical properties of the manufactured components. Numerical simulation of this problem is important since the direct observation of the interaction of bubbles with dendrites is limited by the opacity of metals. Therefore, developing a reliable numerical model is essential to predict the mechanical properties of materials after solidification. The pseudopotential multiphase model is a popular method for simulating multiphase flow using the lattice Boltzmann method. This model and its variations have been used to simulate a variety of problems successfully. However, the original pseudopotential model has some deficiencies, including large spurious current and restriction to model low density and viscosity ratios. Several schemes have been proposed to improve the pseudopotential multiphase model and overcome the limitations, including using a realistic equation of state, introducing a force with higher order of isotropy, introducing a middle-range repulsion force, and implementing the force similarly to the Exact Difference Method (EDM). The aim of this article is to investigate these various enhancements available for the pseudopotential multiphase model in order to come up with a reliable scheme to simulate motion and interaction of bubbles during dendritic solidification in binary alloys. The proposed model is validated against published literature.

scholarly journals Researches on leakage with lubricating oil using a composite multiphase lattice Boltzmann method

2021 ◽  
pp. 135-135
Author(s):  
Yuhan Li ◽  
Minxia Li ◽  
Yusheng Hu ◽  
Jia Xu ◽  
Liping Ren
Keyword(s):  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Phase Distribution ◽  
Passive Scalar ◽  
Lubricating Oil ◽  
Working Fluid ◽  
Experimental Investigations ◽  
Multiphase Model ◽  
Simulation Results ◽  
Boltzmann Method

In this paper, a novel model to investigate leakage of gaseous working fluid in pressured devices with lubricating oil was created with Lattice Boltzmann method and Shan-Chen multiphase model. A method to adapt actual pressure-density relation into the lattice via a self-adapting timestep and simplify the simulation of compressible fluid was developed. A model to simulate two-phased leakage with lubricating oil was created with a combination of Shan-Chen model and passive scalar model. The model can realize the phase distribution simulation in the leakage field without causing the pressure and the inter-phase interactions to overlap. This model is also able to be combined with other multiphase models. After a group of preliminary tests of the model, the characteristics of phase distribution and leakage were investigated qualitatively. Five types of phase distribution in the simulation results were classified, which are: uniformed distribution, sphered drips, gas channel, blocked channel and slug bubbles. The results of simulations show good conformance with actual leakage patterns. Preliminary discussions about the leakage features are made upon the results. However, these simulation results are only qualitative and cannot show the quantitative features in leakages. More experimental investigations should be carried out to realize correlations to the model.

Three-Dimensional Weighted Multiple-Relaxation-Time Pseudopotential Lattice Boltzmann Method for Multiphase Flow

2021 ◽  
Author(s):  
Jun Tang ◽  
Shengyuan Zhang ◽  
Huiying Wu
Keyword(s):  
Relaxation Time ◽  
Multiphase Flow ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Present Model ◽  
Orthogonal Transformation ◽  
Three Dimensional ◽  
Proposed Model ◽  
Multiple Relaxation Time ◽  
Boltzmann Method

Abstract The pseudopotential lattice Boltzmann (LB) method has been widely used for simulating multiphase flow due to its concise concept and computational simplicity. In this paper, based on the weighted orthogonal transformation matrix, a three-dimensional (3D) weighted multiple-relaxation-time pseudopotential lattice Boltzmann method (WRMT-LBM) is developed, in which the standard lattice stencil D3Q19 is adopted. Compared with the classical multiple-relaxation-time pseudopotential lattice Boltzmann method (CMRT-LBM) based on the orthogonal transformation matrix, the expressions of the equilibrium density distribution function and discrete force term in moment space are simplified in the present model, which contributes to simplifying the program implementation and improving the computational efficiency. Moreover, an additional discrete source term in moment space compatible with the proposed model is introduced to achieve tunable surface tension. A series of numerical tests are then implemented to investigate the performance of the proposed model. Compared with the CMRT-LBM, the results of the present model can achieve lower spurious velocity and higher computational efficiency while keeping comparable accuracy. Furthermore, using the present model, three benchmark cases, including droplet oscillation, droplet impacting on wall and droplet impact on thin film, are performed to investigate the performance of this model. The numerical results are in good agreement with the analytical solutions or the empirical correlations in the literature, which demonstrates that the present model can simulate the multiphase flow with large density ratio.

A Study of Fluid Interfaces and Moving Contact Lines Using the Lattice Boltzmann Method

2013 ◽  
Vol 13 (3) ◽  
pp. 725-740 ◽  
Author(s):  
S. Srivastava ◽  
P. Perlekar ◽  
L. Biferale ◽  
M. Sbragaglia ◽  
J.H. M. ten Thije Boonkkamp ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Lattice Boltzmann Method ◽  
Contact Line ◽  
Lattice Boltzmann ◽  
Dynamical Behavior ◽  
Pressure Jump ◽  
Multiphase Model ◽  
Moving Contact ◽  
Wall Boundary Conditions ◽  
Boltzmann Method

AbstractWe study the static and dynamical behavior of the contact line between two fluids and a solid plate by means of the Lattice Boltzmann method (LBM). The different fluid phases and their contact with the plate are simulated by means of standard Shan-Chen models. We investigate different regimes and compare the multicomponent vs. the multiphase LBM models near the contact line. A static interface profile is attained with the multiphase model just by balancing the hydrostatic pressure (due to gravity) with a pressure jump at the bottom. In order to study the same problem with the multicomponent case we propose and validate an idea of a body force acting only on one of the two fluid components. In order to reproduce results matching an infinite bath, boundary conditions at the bath side play a key role. We quantitatively compare open and wall boundary conditions and study their influence on the shape of the meniscus against static and lubrication theory solution.

scholarly journals Multi-component Lattice Boltzmann simulation of the hydrodynamics in drip emitters

2017 ◽  
Vol 48 (3) ◽  
pp. 175
Author(s):  
Giacomo Falcucci ◽  
Vesselin K. Krastev ◽  
Chiara Biscarini
Keyword(s):  
Experimental Data ◽  
Lattice Boltzmann ◽  
Numerical Technique ◽  
Simulation Tool ◽  
Irrigation Systems ◽  
Lattice Boltzmann Simulation ◽  
Proposed Model ◽  
Flow Through ◽  
Boltzmann Method ◽  
Good Agreement

In this paper, we propose a fast and efficient numerical technique based on the Lattice Boltzmann method (LBM) to model the flow through a reference drip emitter geometry. The aim of the study is to demonstrate the applicability of the LBM as a reliable simulation tool for the hydraulic optimisation of irrigation systems. Results for the water flow through a rectangular drip emitter are in good agreement with literature numerical and experimental data. Furthermore, we demonstrate the feasibility of the proposed model to simulate a multi-component flow that could be used to simulate the presence of additives, contaminants, and suspended particles.

scholarly journals Droplet Formation in a T-Junction Microfluidic Device in the Presence of an Electric Field

2015 ◽  
Author(s):  
Zeeshan Ahmad ◽  
Rattandeep Singh ◽  
Supreet Singh Bahga ◽  
Amit Gupta
Keyword(s):  
Electric Field ◽  
Microfluidic Device ◽  
Lattice Boltzmann ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Immiscible Fluids ◽  
Multiphase Model ◽  
Dispersed Phases ◽  
Rate Ratios ◽  
Boltzmann Method

In this work, the effect of applying an electric field on droplet formation in a T-junction microfluidic device is examined by simulations based on a recent technique known as lattice Boltzmann method (LBM). The electric field is applied in the main channel just beyond the confluence of the continuous and dispersed phases. A combined electrohydrodynamics-multiphase model that can simulate the flow of immiscible fluids in the presence of an electric field is developed and validated. The same model is then applied to study the droplet formation process in a T-junction microfluidic device at a capillary number of 0.01 and at different dispersed to continuous phase flow rate ratios. Results show that there is a decrease in the droplet size and an increase in formation frequency as the electric field is increased. The interplay of the electric and interfacial forces on droplet formation is investigated.

Numerical Simulation of the Nanofluid Phase Separation by Lattice Boltzmann Method

2014 ◽  
Vol 989-994 ◽  
pp. 619-622
Author(s):  
Shou Guang Yao ◽  
Xin Wang Jia ◽  
Chang Jiang Zhou ◽  
Yu Hong Nie
Keyword(s):  
Phase Separation ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Base Fluid ◽  
Pure Water ◽  
Lattice Boltzmann Model ◽  
Multiphase Model ◽  
Two Phase ◽  
Separation Phase ◽  
Boltzmann Method

Using shan-chen model of lattice Boltzmann method,considering the interaction between nanoparticles and base fluid, by modifying the nanofluids single-component multiphase model, established the nanofluid multi-component heterogeneous lattice Boltzmann model. The model was used to simulate square cavity phase separation of nanofluids, get the Nanofluid separation phase diagram, compared it with pure water phase separation diagram, the results show that, nanofluid in gas-liquid two phase separation process, the addition of nanoparticles is beneficial to produce bubbles, meanwhile the addition of nanoparticles caused a micro convection inside the base fluid, improved the performance of the spread of the base fluid, leaded to the transmission effect, hindered the coalescence of bubbles.

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