Research

Overview of areas of research within the Laboratory for Scientific Computing.

Computational Multiphysics

The Laboratory is primarily concerned with science and technology applications which necessitate the simultaneous consideration of two or more states of matter, multiple materials and several physical and chemical processes. To this end, at the core of our work is the development of numerical methods for the direct numerical simulation of an arbitrary combination of four states of matter (gas, liquid, solid and plasma).

Multiphase Modelling

In mining or defence applications, condensed-phase explosives interact with one or more compliant inert materials in the ignition or detonation process. Examples include confined rate-sticks and explosives that include gas cavities and solid beads. To model these, a mathematical formulation that can simultaneously model the explosive multi-phase mixture and its immiscible interaction with inert materials is necessary.

Cartesian Mesh Generation

In Computational Fluid Dynamics applications, high-quality mesh generation is a prerequisite for calculating accurate solutions. An attractive alternative to conventional body-fitted or unstructured meshing techniques is offered by the Cartesian cut cell approach. It allows for rapid, automatic, mesh generation for complex geometries, and maintains the computational conveniences offered by the use of Cartesian grids.

Relativistic Hydrodynamics

In astrophysics, an area of interest is Bondi-Hoyle-Lyttleton accretion, which is fluid flow onto a compact object. This typically simulates the accretion of a gas onto a dense object. It is interesting to extend this to accretion onto black holes, and to investigate the dependence of the flow field on the upstream velocity, the spin of the black hole, and any perturbations in the upstream fluid density.

Lightning Strike on Aircraft

Lightning strike on aircraft can lead to serious damage, especially to composite materials, which have low thermal and electrical conductivity. Thorough testing of materials used for aircraft is therefore essential to ensure they can withstand a strike in flight. Numerical simulations can dramatically reduce the time and cost of experimental tests, but this is beyond the capability of current commercial software. To this end, we have developed and applied a multi-physics model of plasma-elastoplastic material interaction.

Ultrasonic Excitation of Substrates

The placement of ultrasonic transducers beneath an aircraft skin has been shown to prevent ice formation on leading edges during flight. This technology is more energy efficient than traditional ice prevention through manual heating of the affected areas. In order to further develop such technology, the physical mechanism through which this behaviour occurs is of interest.

Particulate Flows

The oil and gas industry uses many complex fluids in a wide range of applications. These fluids are usually non-Newtonian in character and possess a variety of characteristics which are not well understood. Many of these characteristics originate from local microscopic interactions in the fluid, particularly in complex fluids containing particle or polymer molecule additives. In such fluids the interactions between the suspended material, the suspension fluid, and the domain boundaries give rise to non-Newtonian characteristics of the bulk fluid.

Condensed Phase Combustion

Condensed phase combustion applications necessitate not only the accurate modelling of the combustible material but also of any materials that surround and interact with it. To this end, at the core of our work is the development of numerical methods for the direct numerical simulation of a combustible material (e.g., gaseous, liquid, solid, explosives, ideal and non-ideal explosives etc.) and its non-linear interaction with an arbitrary combination materials (gas, liquid, solid and plasma).

Additive Manufacturing

Additive manufacturing through the selective laser melting of metal powders allows for the printing of large aircraft parts, with complex geometries that cannot be constructed using conventional processes. Due to the violent nature of the laser melting process, porosity and stress-distortion can occur in a printed part, rendering it unsuitable for use in aircraft manufacture. Numerical simulations can allow us to understand the properties of the finished part, and hence can be used to develop better techniques.

Non-ideal explosives

In mining, condensed-phase explosives are sensitised on site, by adding inhomogeneities to the body of the explosive for optimum performance. The inhomogeneities are in the form of gas cavities or solid beads. The interaction of a shock wave with these inhomogeneities generates hotspots; localised regions of high pressure and temperature that lead to an earlier ignition than the neat material.

Sonic boom prediction

The sonic boom generated by aircraft flying at a supersonic speed is one of the primary problems of the development of supersonic commercial aircraft. Sonic boom prediction tools have been developed based on the weak shock theory, and even complex phenomena are evaluated as simplified models. Hence, because of their limited applications, some complex phenomena such as sonic boom cutoff arising from shock wave diffraction has been difficult to analyze. For improving the state of the art, we focus on Computational Fluid Dynamics (CFD) analysis over the entire flow field, ranging from the near field around a supersonic aircraft to the far field extending to the ground.