Plenary Speakers

Professor Neil Sandham

Neil Sandham has been Professor of Aerospace Engineering at the University of Southampton since 1999, having previously been at Stanford University (PhD 1989), DLR Göttingen and Queen Mary, University of London. His area of expertise is numerical simulation of transitional and turbulent flows over the full range of speeds from incompressible to hypersonic, with current projects in transonic airfoil flows, flow over surface roughness and high-speed aerodynamics. He was the founding principal investigator of the UK Turbulence Consortium and has served as head of the Department of Aeronautics and Astronautics in Southampton.

Talk Title: High-speed aerodynamics using scale-resolving simulations 

Abstract

Numerical simulation offers a route to study complex phenomena that are difficult or expensive to study in laboratory experiments. This is particularly true in high-speed flow applications with transitional and turbulent flow, where measurements are severely limited. In contrast, scale-resolving numerical simulations, for example direct numerical simulations, which set out to resolve all scales of motion, provide complete flowfield data. With developments in high performance computing, large-scale simulations are increasingly feasible and software developments, for example [1], are enabling applications on the latest accelerator hardware. Recent and ongoing work is extending the capabilities of direct and large eddy simulation into the hypersonic flight regime that is relevant to the later stages of atmospheric entry, where the continuum model is applicable, and to sustained high speed flight in the atmosphere.  Here, the usual Navier-Stokes, perfect gas model needs to be extended in a numerically efficient way [2] to accommodate variable fluid properties, as well as possible thermo-chemical non-equilibrium. In this regime, both transition to turbulence [3] and the resulting turbulent flow are modified. We will use examples of recent numerical simulations to illustrate the linear and nonlinear mechanisms involved in flow configurations in which shock waves interact with boundary layers. A shock reflection problem [4,5] is used to explore the linear and nonlinear flow response to perturbations, while a problem with flow over a bump protruding into a hypersonic flow [6] is used to study the interaction between multiple separation bubbles and show how turbulence can sustain, independent of upstream disturbances.

[1] Lusher, D. J., Sansica, A., Sandham, N. D., Meng, J., Siklósi, B., & Hashimoto, A. (2025). OpenSBLI v3. 0: High-fidelity multi-block transonic aerofoil CFD simulations using domain specific languages on GPUs. Computer Physics Communications, 307, 109406.

[2] Musawi, A., & Sandham, N. D. (2025). Efficient Transport Property Formulation for Scale-Resolved Hypersonic Flow Simulations. In AIAA SCITECH 2025 Forum (p. 0340).

[3] Ala, T., & Sandham, N. D. (2025). Effect of Thermal Nonequilibrium on Disturbance Growth in Hypersonic Boundary Layers. In AIAA SCITECH 2025 Forum (p. 1311).

[4] Sandham, N. D., Sharma, P. K. and Lusher, D. J. (2024) Linear and nonlinear response of high-speed boundary layers to continuous stochastic forcing. Proc IUTAM Conference on Laminar-Turbulent Transition, to appear.

[5] Mauriello, M. Sharma, P.K., Larchevêque, L, Sandham, N.D. (2024) Role of non-linearities induced by deterministic forcing in the low-frequency dynamics of transitional SBLI, submitted to J. Fluid Mech.

[6] Walker, M. C., & Sandham, N. D. (2025). Direct Numerical Simulation of Hypersonic Flow Over a Gaussian Bump. In AIAA SCITECH 2025 Forum (p. 2062).

Professor Catherine O'Sullivan

Prof.  Catherine O'Sullivan is a Professor of Particulate Soil Mechanics.  She is currently head of the Geotechnics Section of the Department of Civil and Environmental Engineering at Imperial College. She completed her PhD studies at the University of California, Berkeley, and has worked as a geotechnical engineering California.  Recognition for her research includes the 2015 Géotechnique lecture, the 2016 Shamsher Prakash Research Award, and the 2023 Alert lecture and medal.  Catherine is Editor in Chief of the ASCE Journal of Geotechnical and Geoenvironmental Engineering.  She is the author of  Particulate DEM: A geomechanics perspective and has contributed to over 120 journal papers. 

Talk Title: Coupled phenomena in particulate materials: insights from particle-scale simulations

Abstract

Across many engineering disciplines in which granular or particulate materials are encountered engineers need to predict responses of particles with liquids, gasses, and mixtures of liquids and gases in the space between grains.  Arguably the most important idea in modern soil mechanics is the principle of effective stress put forward by Karl Terzaghi just over a century ago in 1923 (Terzaghi, 1923).  The transformation impact of this principle on soil mechanics and geotechnical engineering (e.g. Clayton et al., 1995) reflects both the importance and challenge of accounting for the interaction between the solid and liquid phases in soil, but also in other particulate materials.  Apart from the multi-phase nature of these materials, the influence of temperature changes and chemistry may also be significant in many cases (e.g. Gens, 2010). A comprehensive model would account for thermal, hydraulic, mechanical and chemical (THMC) couplings.  Despite significant advances our fundamental understanding of the interaction between the phases and phenomena remains incomplete, compromising our ability to accurately model or predict behaviour.

This presentation will discuss the application of discrete element method (DEM) simulations, coarse-grained molecular dynamics, pore-network-modelling, and finite volume method computational fluid dynamics simulations to advance understanding of key coupled phenomena in sand and clay.  The talk will address liquid-particle interactions considering both Newtonian and non-Newtonian fluids, the impact of pore-fluid chemistry on clay behaviour, the response of granular materials to changes in temperature change, and the challenge of accurately modelling the pressure field when the pore-space includes multiple fluid phases.  While the motivation for the research presented is in the remit of geotechnical engineering, the fundamental mechanics are relevant to many applications in chemical, process and mechanical engineering.  Throughout the presentation this more general perspective will be emphasized.

References:

Clayton, C R I Muller Steinhagen, H M Steinhagen, W Powrie, K Terzaghi, And A W Skempton (1995) Terzaghi's theory of consolidation, and the discovery of effective stress. (compiled from the work of K. Terzaghi And A.W. Skempton).  Proceedings Of The Institution Of Civil Engineers - Geotechnical Engineering 1995 113:4, 191-205

Gens, A. (2010) Soil–environment interactions in geotechnical engineering, 47th Rankine Lecture, Géotechnique 60 (1), 3-74

Terzhaghi, K. (1923) Die Berechnung der Durchlassigkeitsziffer des Tones aus Dem Verlauf der Hidrodynamichen Span-Nungserscheinungen, Akademie der Wissenschaften in Wien; Mathematish-Naturwissen-SchaftilicheKlasse: Mainz, Germany, 1923; pp. 125–138

Professor Mark Parsons 

Prof. Mark Parsons is EPCC’s Director, the supercomputing centre at The University of Edinburgh. EPCC operates a wide variety of computing systems for modelling and simulation and AI, including the UK’s current national supercomputer (ARCHER2). He joined EPCC in 1994 as a software developer working on several industrial contracts following a PhD in Particle Physics undertaken on the LEP accelerator at CERN in Geneva. In 1997 he became the Centre’s Commercial Manager and subsequently its Commercial Director. Today, he is also the Dean of Research Computing at the University of Edinburgh. He has many interests in supercomputing ranging from its industrial use to novel hardware designs. He was the Chair of the Gordon Bell Prize in 2021 and also involved in the establishment of PRACE and EuroHPC.

Talk Title: 

Computational engineering in the Exascale age

Abstract

The UK was at the forefront of the development of parallel computing in the 1980s and early 1990s. It has always had a very active and inventive computational science community. Since 1994 the UK has had a national supercomputing service, almost all having been hosted and operated by EPCC, the supercomputing centre at the University of Edinburgh. ARCHER2 is almost one million times more powerful than 1994’s Cray T3D. Despite this, the UK’s fastest supercomputer, is only 62nd in the world rankings.

The majority systems faster than ARCHER2 use GPU accelerators, and this talk will look at why GPUs are used for acceleration, the pros and cons of this approach and what the UK’s next national supercomputer may look like. A key part of the next national service will focus on computational challenge focussed projects. Over the past 5 years, EPCC along with Rolls Royce has led the ASiMoV Prosperity Partnership project which set itself the challenge of modelling a full gas turbine engine in operation at high fidelity within 10 years. The talk will use this example to discuss the computational science challenges faced when tackling problems fit for the Exascale age.

Dr Paulo R. Refachinho de Campos - UKACM 2023 Roger Owen Prize

Dr. Paulo R. Refachinho de Campos obtained his MSc degree from the University of São Paulo, Brazil, in 2018, before joining Swansea University. He earned a PhD from both Swansea University and Universitat Politècnica de Catalunya in 2023, achieving an Excellent Cum Laude grade. His PhD thesis explores novel meshless methods, particularly the Smoothed Particle Hydrodynamics (SPH) method, with applications in Fast Solid Dynamics. Since then, Paulo has maintained strong collaborations with Swansea University and the University of Glasgow, resulting in further publications extending the original PhD work into the fields of thermo-coupled events and dynamic fracture. Paulo has also joined Dassault Systemes as a research and development engineer, where he is responsible for the development and implementation of fatigue algorithms in their durability software.

Dr. Paulo R. Refachinho de Campos is the winner of the 2023 UKACM Roger Owen Prize. In his talk, he will present a review of recent developments in Smoothed Particle Hydrodynamics for Fast Dynamics.

Talk Title: Smoothed Particle Hydrodynamics for fast dynamics: from displacement-based formulations to first-order conservation laws 

Abstract

Fast dynamics encompasses a range of applications characterised by short time durations, high energy events, and extreme physical phenomena such as impacts, shocks, large deformations, fracture, and fragmentation. These scenarios span diverse fields, including drop tests for handheld devices, car crash simulations, bird impacts on aircraft, ballistic and armor analysis, space debris collisions, and even interplanetary impacts. Despite their variety, these events share commonalities in the underlying physical phenomena, economic significance, and computational challenges. The finite element method (FEM), a widely adopted mesh-based technique, has achieved great success in modeling such problems. However, meshless alternatives have also been successfully explored in cases of extreme deformation, as well as in the simulation of fracture and fragmentation processes.

This presentation will explore the use of the Smoothed Particle Hydrodynamics (SPH) meshless method as a competitive alternative to traditional mesh-based approaches for simulating critical phenomena in fast dynamics. The discussion will begin by revisiting the foundational principles of the classic displacement-based SPH formulation [1], highlighting the strengths of meshless techniques while critically addressing the inherent limitations of SPH. Building on this foundation, the talk will evolve into a modern approach developed over the past decade, which leverages the discretisation of a system of first-order conservation laws using SPH [2,3]. This methodology not only provides a versatile framework for representing solid dynamics across diverse configurations (e.g., Total Lagrangian and Updated Lagrangian formulations) but also enables the integration of robust numerical stabilisation techniques, many of which have been successfully employed in Computational Fluid Dynamics (CFD).

REFERENCES 

[1] Libersky, L. D., Petschek, A. G., Carney, T. C., Hipp, J. R., Allahdadi, F. A. High strain Lagrangian Hydrodynamics. Journal of Computational Physics (1993) 109:67-75. 

[2] Hean Lee, C., Gil, A. J., Ghavamian, A., Bonet, J. A Total Lagrangian upwind Smooth Particle Hydrodynamics algorithm for large strain explicit solid dynamics. Comput. Methods Appl. Mech. Engrg. (2019) 344:209-250. 

[3] Refachinho de Campos, P. R., Gil, A. J., Hean Lee, C., Giacomini, M., Bonet, J. A New Updated Reference Lagrangian Smooth Particle Hydrodynamics algorithm for isothermal elasticity and elasto-plasticity. Comput. Methods Appl. Mech. Engrg. (2022) 392:114680.