Engineering & Physical Sciences
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Item A study of pseudopotential lattice Boltzmann method with applications to thermal bubble nucleation(Heriot-Watt University, 2020-09) Pasieczynski, Kamil; Chen, Doctor BaixinThe nature of the work dealt with in this thesis is mathematical modelling of multiphase flows. The main objective of this doctoral work was to study multiphase lattice Boltzmann models (LBM) and to develop an advanced pseudopotential model. Specifically, advanced thermal lattice Boltzmann models were applied to study bubble nucleation in nucleate pool boiling at subatmospheric pressures. The numerical investigations carried out as part of this work follow the format well-established in the literature and allow further studies in more complex geometries. The work carried out contributes to current discussions in the literature and fulfils the recommendations of a number of authors. Fluid-fluid interactions in the Yuan-Schaefer, multipseudopotential interaction and piecewise linear equation of state methods were investigated. Multipseudopotential interaction was established as a practicable method of multiphase simulations by combination with the multiple relaxation time collision operator, surface tension modification methods and with modified temperature double distribution function and hybrid (4th order Runge-Kutta) thermal LBM models. Thermal LBM simulations were found to agree well with experimental findings on the influence of subatmospheric pressure on bubble nucleation. It was found that as pressure is lowered in LBM simulations the size of bubbles nucleated increases, according to bubble diameter ~ pressure-1 , with results falling in between experimental data for brass and stainless steel tubes.Item A study of pseudopotential lattice Boltzmann method with applications to thermal bubble nucleation(Engineering and Physical Sciences, 2020-05) Pasieczynski, Kamil; Chen, Doctor BaixinThe nature of the work dealt with in this thesis is mathematical modelling of multiphase flows. The main objective of this doctoral work was to study multiphase lattice Boltzmann models (LBM) and to develop an advanced pseudopotential model. Specifically, advanced thermal lattice Boltzmann models were applied to study bubble nucleation in nucleate pool boiling at subatmospheric pressures. The numerical investigations carried out as part of this work follow the format well-established in the literature and allow further studies in more complex geometries. The work carried out contributes to current discussions in the literature and fulfils the recommendations of a number of authors. Fluid-fluid interactions in the Yuan-Schaefer, multipseudopotential interaction and piecewise linear equation of state methods were investigated. Multipseudopotential interaction was established as a practicable method of multiphase simulations by combination with the multiple relaxation time collision operator, surface tension modification methods and with modified temperature double distribution function and hybrid (4th order Runge-Kutta) thermal LBM models. Thermal LBM simulations were found to agree well with experimental findings on the influence of subatmospheric pressure on bubble nucleation. It was found that as pressure is lowered in LBM simulations the size of bubbles nucleated increases, according to bubble diameter ~ pressure-1 , with results falling in between experimental data for brass and stainless steel tubes