A finite element method for GPU-based elastic wave modelling in solid-fluid media using displacement fields
File(s)
Author(s)
Simillides, Yiannis
Type
Thesis
Abstract
Ultrasonic wave propagation and scattering involving both solids and fluids underpin many
key configurations in non-destructive testing and underwater acoustics. The resulting interactions
are highly dependent on both material parameters and geometries and are often difficult
and expensive to investigate experimentally. Modelling capabilities are often used to overcome
this, but these are also complex and computationally expensive due to the complexity
of the fluid-solid interactions.
In this thesis, work is presented on simulating ultrasonic wave phenomena involving both
solids and fluids, using the finite element method implemented on graphical processing units.
The thesis beings with a literature review existing analytical and numerical methods as well
as certain necessary building blocks and useful background information.
A novel explicit time-domain finite element method for simulating ultrasonic waves interacting
with fluid-solid interfaces is then introduced, allowing investigation of complex, industrially
relevant configurations at scale and speed. The method is displacement-based, and relies
on classical hourglassing control, in addition to a modified time-stepping scheme to damp
out any shear motion in an inviscid fluid. One of the key benefits of the displacement-based
approach is that nodes in the fluid have the same number of degrees of freedom as those in
the solid. Therefore, defining a fluid-solid model is as easy as defining an all-fluid or all-solid
model, avoiding the need for any special treatments at the interfaces common in other approaches.
It is thus compatible with typical elastodynamic finite element formulations and
ready for implementation on a graphical processing unit.
The method has been verified across a range of problems that involve millions of degrees of
freedom from different fields, such as non-destructive testing and underwater acoustics, and
across different scales, with frequencies of interest ranging from kHz to MHz. There is also a
brief investigation on geometrical model refinement and some initial research and simulations
conducted to extend this work in three dimensions.
key configurations in non-destructive testing and underwater acoustics. The resulting interactions
are highly dependent on both material parameters and geometries and are often difficult
and expensive to investigate experimentally. Modelling capabilities are often used to overcome
this, but these are also complex and computationally expensive due to the complexity
of the fluid-solid interactions.
In this thesis, work is presented on simulating ultrasonic wave phenomena involving both
solids and fluids, using the finite element method implemented on graphical processing units.
The thesis beings with a literature review existing analytical and numerical methods as well
as certain necessary building blocks and useful background information.
A novel explicit time-domain finite element method for simulating ultrasonic waves interacting
with fluid-solid interfaces is then introduced, allowing investigation of complex, industrially
relevant configurations at scale and speed. The method is displacement-based, and relies
on classical hourglassing control, in addition to a modified time-stepping scheme to damp
out any shear motion in an inviscid fluid. One of the key benefits of the displacement-based
approach is that nodes in the fluid have the same number of degrees of freedom as those in
the solid. Therefore, defining a fluid-solid model is as easy as defining an all-fluid or all-solid
model, avoiding the need for any special treatments at the interfaces common in other approaches.
It is thus compatible with typical elastodynamic finite element formulations and
ready for implementation on a graphical processing unit.
The method has been verified across a range of problems that involve millions of degrees of
freedom from different fields, such as non-destructive testing and underwater acoustics, and
across different scales, with frequencies of interest ranging from kHz to MHz. There is also a
brief investigation on geometrical model refinement and some initial research and simulations
conducted to extend this work in three dimensions.
Version
Open Access
Date Issued
2023-03
Date Awarded
2024-02
Copyright Statement
Creative Commons Attribution NonCommercial Licence
License URL
Advisor
Huthwaite, Peter
Lowe, Michael
Kalkowski, Michal
Publisher Department
Mechanical Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)