scholarly journals A Multiple-Grid Lattice Boltzmann Method for Natural Convection under Low and High Prandtl Numbers

Fluids ◽  
2021 ◽  
Vol 6 (4) ◽  
pp. 148
Author(s):  
Seyed Amin Nabavizadeh ◽  
Himel Barua ◽  
Mohsen Eshraghi ◽  
Sergio D. Felicelli

A multi-distribution lattice Boltzmann Bhatnagar–Gross–Krook (BGK) model with a multiple-grid lattice Boltzmann (MGLB) model is proposed to efficiently simulate natural convection over a wide range of Prandtl numbers. In this method, different grid sizes and time steps for heat transfer and fluid flow equations are chosen. The model is validated against natural convection in a square cavity, since extensive benchmark solutions are available for that problem. The proposed method can resolve the computational difficulty in simulating problems with very different time scales, in particular, when using extremely low or high Prandtl numbers. The technique can also enhance computational speed and stability while keeping the simplicity of the BGK method. Compared with the conventional lattice Boltzmann method, the simulation time can be reduced up to one-tenth of the time while maintaining the accuracy in an acceptable range. The proposed model can be extended to other lattice Boltzmann collision models and three-dimensional cases, making it a great candidate for large-scale simulations.

Author(s):  
Ridha Djebali ◽  
Mohammed El Ganaoui ◽  
Habib Sammouda

The lattice Boltzmann method based on the BGK model has been used to simulate laminar natural convection in a heated rectangular cavity on the uniform grid. The hydrodynamic and thermal fields are solved by using the double populations approach. A general benchmark has been carried out to show the effects of secondary parameters at their wide range. Excellent agreement is obtained by comparison with available literature.


Author(s):  
Anoosheh Niavarani-Kheirier ◽  
Masoud Darbandi ◽  
Gerry E. Schneider

The main objective of the current work is to utilize Lattice Boltzmann Method (LBM) for simulating buoyancy-driven flow considering the hybrid thermal lattice Boltzmann equation (HTLBE). After deriving the required formulations, they are validated against a wide range of Rayleigh numbers in buoyancy-driven square cavity problem. The performance of the method is investigated on parallel machines using Message Passing Interface (MPI) library and implementing domain decomposition technique to solve problems with large order of computations. The achieved results show that the code is highly efficient to solve large scale problems with excellent speedup.


2016 ◽  
Vol 26 (4) ◽  
pp. 735-747
Author(s):  
Kai Feldhusen ◽  
Ralf Deiterding ◽  
Claus Wagner

Abstract Utilizing the Boussinesq approximation, a double-population incompressible thermal lattice Boltzmann method (LBM) for forced and natural convection in two and three space dimensions is developed and validated. A block-structured dynamic adaptive mesh refinement (AMR) procedure tailored for the LBM is applied to enable computationally efficient simulations of moderate to high Rayleigh number flows which are characterized by a large scale disparity in boundary layers and free stream flow. As test cases, the analytically accessible problem of a two-dimensional (2D) forced convection flow through two porous plates and the non-Cartesian configuration of a heated rotating cylinder are considered. The objective of the latter is to advance the boundary conditions for an accurate treatment of curved boundaries and to demonstrate the effect on the solution. The effectiveness of the overall approach is demonstrated for the natural convection benchmark of a 2D cavity with differentially heated walls at Rayleigh numbers from 103 up to 108. To demonstrate the benefit of the employed AMR procedure for three-dimensional (3D) problems, results from the natural convection in a cubic cavity at Rayleigh numbers from 103 up to 105 are compared with benchmark results.


Author(s):  
Mo Yang ◽  
Yuwei Zhou ◽  
Yuwen Zhang ◽  
Enjie Bian ◽  
Zheng Li

The Lattice Boltzmann method is used to simulate the flow patterns of natural convection in horizontal cylindrical annulus for aspect ratios in the range of 0.4≤A≤10 and for Prandtl numbers varying from 0.1 to 0.7. At Pr = 0.3 and A = 2, flow patterns on the whole range of Rayleigh number are mapped indicating the lower and upper critical values for transitions. At Pr = 0.7, the influence of aspect ratio on flow pattern is analyzed acquiring the result that the oscillation flow never happens at A≤3. At A = 2, several Prandtl numbers are calculated at certain Rayleigh number and the conclusion is that the steady upward flow keeps when 0.5≤Pr. The results are found in good agreement with existed studies.


2009 ◽  
Vol 23 (24) ◽  
pp. 4907-4932 ◽  
Author(s):  
ABBAS FAKHARI ◽  
MOHAMMAD HASSAN RAHIMIAN

In this paper, the lattice Boltzmann method is employed to simulate buoyancy-driven motion of a single bubble. First, an axisymmetric bubble motion under buoyancy force in an enclosed duct is investigated for some range of Eötvös number and a wide range of Archimedes and Morton numbers. Numerical results are compared with experimental data and theoretical predictions, and satisfactory agreement is shown. It is seen that increase of Eötvös or Archimedes number increases the rate of deformation of the bubble. At a high enough Archimedes value and low Morton numbers breakup of the bubble is observed. Then, a bubble rising and finally bursting at a free surface is simulated. It is seen that at higher Archimedes numbers the rise velocity of the bubble is greater and the center of the free interface rises further. On the other hand, at high Eötvös values the bubble deforms more and becomes more stretched in the radial direction, which in turn results in lower rise velocity and, hence, lower elevations for the center of the free surface.


2021 ◽  
Vol 32 (1) ◽  
pp. 21-28
Author(s):  
Umar Fauzi

The Lattice Boltzmann Method is one of the computational fluid dynamics methods that can be applied to simulate fluid based on the microscopic and kinetic theory of gases. In this study, earth mantle convection is simulated by combining the concept of lid-driven cavity simulation and natural convection using the Lattice Boltzmann method in a two-dimensional system (D2Q9). The results of the lid-driven cavity and natural convection simulation are comparable to previous works. This study shows that at a certain lid velocity, the direction of the moving plume is changed. This earth mantle convection simulation will give better and more reliable results by considering more complicated boundary conditions and adequate simulation systems.


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