Two-dimensional lattice Boltzmann modeling for effective thermal conductivity in carbon black filled composites

2017 ◽  
Vol 52 (15) ◽  
pp. 2047-2053 ◽  
Author(s):  
Yong-Jun Kim ◽  
Yu-Fei Tan ◽  
Sok Kim

Polymer composites filled with thermally conductive particles are widely used in thermo-electronic industry, and the prediction of effective properties is still important for design and use of composites. Thus, we propose a lattice Boltzmann model to predict the effective thermal conductivity of composites filled with carbon black. First, a method for reconstructing numerical material having filler distribution characteristic similar to that of actual material is introduced, and the process for obtaining the phase function and the volume fraction of grain filler is described. The energy transport governing equation is then solved through the two-dimensional discrete structure by using a lattice Boltzmann model. The effective thermal conductivity of two-phase composite is expressed by the conductivity of each phase and the temperature distribution in discrete rectangle. The resultant prediction is compared with theoretical and experimental data and indicates good agreement with experimental data.

Water ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 439 ◽  
Author(s):  
Sara Venturi ◽  
Silvia Di Francesco ◽  
Martin Geier ◽  
Piergiorgio Manciola

This work compares three forcing schemes for a recently introduced cascaded lattice Boltzmann shallow water model: a basic scheme, a second-order scheme, and a centred scheme. Although the force is applied in the streaming step of the lattice Boltzmann model, the acceleration is also considered in the transformation to central moments. The model performance is tested for one and two dimensional benchmarks.


2009 ◽  
Vol 52 (4) ◽  
pp. 681-693 ◽  
Author(s):  
Chen Feng ◽  
Xu Ai-Guo ◽  
Zhang Guang-Cai ◽  
Gan Yan-Biao ◽  
Cheng Tao ◽  
...  

Author(s):  
Ajay Vadakkepatt ◽  
Bradley L. Trembacki ◽  
Sanjay R. Mathur ◽  
Jayathi Y. Murthy

Simulations of lithium ion batteries on a cell level are usually performed with volume averaging methods that employ effective transport properties. Bruggeman’s model, which is widely used to determine these effective properties, is solely based on the volume fraction of these porous electrodes. However, other factors like the topology and microstructure of electrodes also play a crucial role in determining effective properties. In this paper, a general derivation of the effective thermal conductivity of multiphase materials, which can be correlated with these factors, is derived using the volume averaging technique. For demonstration, three-dimensional microstructures of various porous materials are reconstructed from scanned images. These images are used to generate fully-resolved finite volume meshes representing the various constituents. The resulting mesh is then employed for numerical analysis of thermal transport, results from which are used for correlating the effective thermal conductivity with various parameters describing the microstructure. It is shown that commonly used power law exponents in the Bruggeman model for effective thermal conductivity must be recalibrated to fit the effective thermal conductivity computed from these detailed simulations.


2011 ◽  
Vol 10 (3) ◽  
pp. 767-784 ◽  
Author(s):  
Amit Gupta ◽  
Ranganathan Kumar

AbstractA two-dimensional lattice Boltzmann model has been employed to simulate the impingement of a liquid drop on a dry surface. For a range of Weber number, Reynolds number and low density ratios, multiple phases leading to breakup have been obtained. An analytical solution for breakup as function of Reynolds and Weber number based on the conservation of energy is shown to match well with the simulations. At the moment breakup occurs, the spread diameter is maximum; it increases with Weber number and reaches an asymptotic value at a density ratio of 10. Droplet breakup is found to be more viable for the case when the wall is non-wetting or neutral as compared to a wetting surface. Upon breakup, the distance between the daughter droplets is much higher for the case with a non-wetting wall, which illustrates the role of the surface interactions in the outcome of the impact.


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