Development of mesoscopic computational methods | Boltzmann

DEVELOPMENT OF MESOSCOPIC COMPUTATIONAL METHODS BASED
ON THE BOLTZMAN EQUATION AND THEIR APPLICATION TO
TURBULENT FLOWS, COMPRESSIBLE THERMAL FLOWS, AND
MULTIPHASE FLOWS
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INTRODUCTION
Almost all objects of engineering are immersed in either water or air or both or in their
operations utilize working fluid. This is true particularly for the case of the machines for
conversion as well as generation of energy like for the case of turbines, engines as well as other
renewable devices of energy like wave energy –converters and wind turbines. Modelling such
devices will therefore require much enabling technology in the Chinese engineering field.
(Drikakis, Frank and Tabor, 2019).
Research Background
The primary aim of this study will be to assist in the Development of mesoscopic computational
methods based on the Boltzmann equation and their application to turbulent flows, compressible
thermal flows, and multiphase flows. Computational Fluid Dynamics (CFD) has been identified
as one element which is used in Digital Engineering. Majority of these methods have however
been rendered impractical due to their higher costs of computation in most of the problems. The
method of e lattice Boltzmann (LB) is basically located at the centre of the modelling as well as
simulation hierarchy. The LB is an approach of mesoscopic which is based on the theory of
kinetics as expressed by the original equation of Boltzmann (Nguyen, Wagner and Simon 2019).
Significance of the Study
In some cases there is a minimal form of the equation of Boltzmann in which the principles of
microscopic energy are preserved and are used in the recovery of the hydrodynamic behavior at
the scale considered to be macroscopic. The method of LB is therefore based on the picture of

the particle with the principle aim of predicting the properties of the macroscopic particles. The
nature of the scale- bridging has been considered to be very fundamental as far as the concept of
engineering is concerned in China. The level of technology in the Chinese industries is likely to
improve with the proper understanding of LB concept. In this context, it will allow for the
incorporation of the crucial mesoscopic or microscopic physics while carrying out the recovery
of the laws of the macroscopic as well as characteristics at the computational costs which are
basically affordable (Kaiser et al.2017).
Scope of the work
This particular study was limited to development of mesoscopic computational methods based on
the Boltzmann equation and their application to turbulent flows, compressible thermal flows, and
multiphase flows.
LITERATURE REVIEW
Turbulence Modelling
Turbulence refers to a state of motion of the fluid which has been characterized by tye
occurrence of fluctuations which are random and are of varying scales during the processes o the
flow. In fact the best description has always been the pseudo-random process and its
characterization is done in terms of the individual coherent eddies of various sizes ranging from
largest eddy scale known to be responsible for driving the turbulence down to Kolmogorov
length scale. This determined by the viscosity. The challenge of turbulence modelling usually
constitutes a representation of the fluctuations at random in forms considered to be cheaper. In
other words the processes of making good use of the statistical representations instead of explicit