Moment‐based boundary conditions for straight on‐grid boundaries in three‐dimensional lattice Boltzmann simulations

Krastiņš, Ivars; Kao, Anne; Pericleous, K.; Reis, Timothy

doi:10.1002/fld.4856

Cited by 16 publications

(12 citation statements)

References 58 publications

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“…Its shortcoming, at present, is geometric flexibility. The methodology may be extended to higher dimensional lattices, and this discussion is reserved for a future publication [52]. The suitability of the methodology to complex geometries is yet to be seen.…”

Section: Resultsmentioning

confidence: 99%

Assessing moment-based boundary conditions for the lattice Boltzmann equation: A study of dipole-wall collisions

2018

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The accuracy of moment-based boundary conditions for no slip walls in lattice Boltzmann simulations is examined numerically by using the dipole-wall collision benchmark test for both normal and oblique cases. In the normal case the dipole hits the wall perpendicularly while in the oblique case the dipole hits the wall at an angle of 30 • to the horizontal. Boundary conditions are specified precisely at grid points by imposing constraints upon hydrodynamic moments only. These constraints are then translated into conditions for the unknown lattice Boltzmann distribution functions at boundaries. The two relaxation time (TRT) model is used with a judiciously chosen product of the two relaxation times. Stable results are achieved for higher Reynolds number up to 10000 for the normal collision and up to 7500 for the oblique case. An excellent agreement with a benchmark data is observed and the local boundary condition implementation is shown to be second order accurate.

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Section: Resultsmentioning

confidence: 99%

Assessing moment-based boundary conditions for the lattice Boltzmann equation: A study of dipole-wall collisions

2018

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“…However, this approach is limited to 2D implementations. In this work, to reduce the singularities and improve the performance of numerical simulation, an approach to treating the corner boundary condition is proposed for the DUGKS based on the D3Q19 model with 19 independent moments [ 73 ].

…”

Section: Methodsmentioning

confidence: 99%

Three-Dimensional Simulations of Anisotropic Slip Microflows Using the Discrete Unified Gas Kinetic Scheme

Guo

Hou

2022

Entropy

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The specific objective of the present work study is to propose an anisotropic slip boundary condition for three-dimensional (3D) simulations with adjustable streamwise and spanwise slip length by the discrete unified gas kinetic scheme (DUGKS). The present boundary condition is proposed based on the assumption of nonlinear velocity profiles near the wall instead of linear velocity profiles in a unidirectional steady flow. Moreover, a 3D corner boundary condition is introduced to the DUGKS to reduce the singularities. Numerical tests validate the effectiveness of the present method, which is more accurate than the bounce-back and specular reflection slip boundary condition in the lattice Boltzmann method. It is of significance to study the lid-driven cavity flow due to its applications and its capability in exhibiting important phenomena. Then, the present work explores, for the first time, the effects of anisotropic slip on the two-sided orthogonal oscillating micro-lid-driven cavity flow by adopting the present method. This work will generate fresh insight into the effects of anisotropic slip on the 3D flow in a two-sided orthogonal oscillating micro-lid-driven cavity. Some findings are obtained: The oscillating velocity of the wall has a weaker influence on the normal velocity component than on the tangential velocity component. In most cases, large slip length has a more significant influence on velocity profiles than small slip length. Compared with pure slip in both top and bottom walls, anisotropic slip on the top wall has a greater influence on flow, increasing the 3D mixing of flow. In short, the influence of slip on the flow field depends not only on slip length but also on the relative direction of the wall motion and the slip velocity. The findings can help in better understanding the anisotropic slip effect on the unsteady microflow and the design of microdevices.

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“…where g is the acceleration due to gravity, b C is the solutal expansion coefficient, and C 0 is a reference concentration set to bulk conditions. TESA consists of four key solvers: a cellular automata (CA) method for solidification 19 based on the lMatIC code, [20][21][22][23] a lattice Boltzmann method 24 for hydrodynamics, and finite difference methods for electromagnetism and the transport equations. TESA 25,26 has been validated and applied to various similar systems, including a study of channel formation in Ga-25 wt%In alloy.…”

Section: Methodsmentioning

confidence: 99%

Magnetic Effects on Microstructure and Solute Plume Dynamics of Directionally Solidifying Ga-In Alloy

Kao

Shevchenko

et al. 2020

JOM

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The effects of applying a 0.2-T transverse magnetic field on a solidifying Ga-25 wt%In alloy have been investigated through a joint experimental and numerical study. The magnetic field introduced significant changes to both the microstructure and the dynamics of escaping high-concentration Ga plumes. Plume migration across the interface was quantified and correlated to simulations to demonstrate that thermoelectric magnetohydrodynamics (TEMHD) is the underlying mechanism. TEMHD introduced macrosegregation within the dendritic structure, leading to the formation of a stable “chimney” channel by increasing the solutal buoyancy in the flow direction. The resulting pressure difference across the solidification front introduced a secondary hydrodynamic phenomenon that subsequently caused solute plume migration.

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Moment‐based boundary conditions for straight on‐grid boundaries in three‐dimensional lattice Boltzmann simulations

Cited by 16 publications

References 58 publications

Assessing moment-based boundary conditions for the lattice Boltzmann equation: A study of dipole-wall collisions

Assessing moment-based boundary conditions for the lattice Boltzmann equation: A study of dipole-wall collisions

Three-Dimensional Simulations of Anisotropic Slip Microflows Using the Discrete Unified Gas Kinetic Scheme

Magnetic Effects on Microstructure and Solute Plume Dynamics of Directionally Solidifying Ga-In Alloy

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