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Low, Wei Chian (2026) Development of a mesh-less algorithm for modelling Fluid Structure Interaction (FSI) problems involving free surface and material fracture. PhD thesis, University of Nottingham.

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Abstract

Water hazards, such as floods (including all types, e.g., tsunamis), are among the most frequent natural disasters that cause significant damage to infrastructure. The multi-physics nature of the occurrence has made it a challenge to develop a realistic numerical model for simulating the phenomena in flood. The flood phenomena typically involve highly deformed free surface flow and complex interaction with composite structures such as those constructed from concrete and reinforced concrete (RC). It could be challenging to apply conventional mesh-based methods in those scenarios. The objective of this thesis is therefore to develop a numerical model that could capture the actual physics such as free-surface flow, solid-solid contact and structural failure by utilizing meshless numerical tools, with application to simulating structural failure during water hazards. The meshless methods considered are smoothed particle hydrodynamics (SPH) and lattice particle method (LPM) (also known as volume compensated particle method (VCPM)) where SPH is used to describe fluid flow while LPM/VCPM is used for solid model. The two methods are coupled and implemented in a highly optimized open-source SPH code, DualSPHysics.

In the first part of the thesis, the LPM structural solver is extended to model composite structures, and the coupled SPH-LPM solver is applied to simulate FSI cases involving composite body and free surface. The LPM composite model is modelled in two ways, first by considering the direction-dependent material symmetry and second, by explicitly representing the constituent materials in structures like laminated composite with clear material interface(s). A force averaging approach is proposed and verified to model the material interface with varying Young’s modulus ratio across it. The practicability and accuracy of the solver without the presence of fracture in structure is demonstrated through various FSI test cases.

Next, the LPM method is coupled with a local isotropic damage model to simulate quasi-brittle fracture. A calibration procedure conducted through mode I fracture test is described to estimate the characteristic length scale in the damage model for the respective lattice structures adopted. The calibrated length scales are then used in all the following test cases. Exhaustive validations against experimental results in terms of crack path and structural response are carried out. Positive outcomes, in line with the experimental findings, have been obtained for the problems investigated which cover mode I and complex mixed mode fractures. With particle refinement, convergence of simulated crack path and structural response are obtained.

In the final part of the thesis, the LPM model is further developed to model the failure of reinforced concrete structures. The predictive capability and generality of the proposed LPM model is assessed against experimental results covering a wide range of failure modes seen in RC beams. Key features of the flexural and shear failure in RC beams are captured by the model. Then, the coupled SPH-LPM method is applied to simulate several FSI test cases with solid fractures. The capability of the current method in tackling complex, real-world FSI cases with structural failure is demonstrated through the test case of failure of plain and reinforced concrete wall due to tsunami-type wave.

Item Type:	Thesis (University of Nottingham only) (PhD)
Supervisors:	Ng, Khai Ching Ng, Hoon Kiat
Keywords:	lattice particle method; volume compensated particle method; smoothed particle hydrodynamics; reinforced concrete; shear failure; fluid structure interaction; fracture analysis
Subjects:	T Technology > TA Engineering (General). Civil engineering (General)
Faculties/Schools:	University of Nottingham, Malaysia > Faculty of Science and Engineering — Engineering > Department of Mechanical, Materials and Manufacturing Engineering
Item ID:	83064
Depositing User:	Low, Wei
Date Deposited:	07 Feb 2026 04:40
Last Modified:	07 Feb 2026 04:40
URI:	https://eprints.nottingham.ac.uk/id/eprint/83064

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