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ENCIT 2020
18th Brazilian Congress of Thermal Sciences and Engineering
NUMERICAL STUDY OF THE PSEUDOPOTENTIAL LATTICE BOLTZMANN METHOD THERMODYNAMIC CONSISTENCY FOR FLAT INTERFACES
Submission Author:
Luiz Czelusniak , SP
Co-Authors:
Luiz Czelusniak, Luben Cabezas Gómez
Presenter: Luiz Czelusniak
doi://10.26678/ABCM.ENCIT2020.CIT20-0451
Abstract
The pseudopotential lattice Boltzmann method has growing as an alternative tool for multiphase simulations in respect with traditional CFD (Computational Fluid Dynamics) techniques. Recently, many works were developed to overcome the limitations of the original pseudopotential method. These works extended the method to provide improved thermodynamic consistency and tunable surface tension. The thermodynamic consistency is assured by adding a new term into the macroscopic pressure tensor. By adjusting the coefficient of this term, it is possible to control the shape of the coexistence curve. In this way, before a numerical simulation be carried, it is necessary to determine which is the correct value of this coefficient that provide thermodynamic consistency for a specific equation of state. In this work it is developed a numerical routine to determine the theoretical value of this coefficient. The procedure is tested for two different equations of state (EOS), for the Carnahan-Starling EOS the theoretical coexistence curve was determined within 1.5e0-3 % of accuracy, while for the Peng-Robinson EOS the higher deviation was smaller then 0.12 %. Also, it was noted that for both cases at lower reduced temperatures a small change in the coefficient that controls the coexistence curve promotes a large variation in the phase densities. After that the theoretical coexistence curve of the pseudopotential lattice Boltzmann method was compared with the results from numerical simulation in order to quantify the discretization errors. It was discovered that the gas phase densities obtained by numerical simulation deviates almost 140 % then the predicted by the theory for reduced temperature close to Tr=0.5 which suggest that discretization errors play an important role for small reduced temperatures.
Keywords
Lattice Boltzmann method, Pseudopotential Method, Thermodynamic Consistency
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