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EPSRC CDT in Next Generation Computational Modelling

Seminar by David Hahn - Simulating with Surfaces: Physics-based visual effects for fractures and fluids

Fractured solids and water flow animations.

Today the NGCM were pleased to welcome fourth-year PhD student David Hahn from the Institute of Science and Technology (IST) Austria, to present research from the Wojtan group on physics-based visual effects for fractures and fluids.

David's work uses surface-based numerical methods to create realistic simulations of complex physical interactions, such as fracturing solid objects and splashing fluid flows. A significant challenge in this area of research is ensuring the simulations are visually representative, while still being computationally efficient enough to run on a desktop computer in a reasonable time frame. Computational simulations are well suited to the creation of visual effects due to easy automation of the process, and the ability to give substantial control of the scene to the visual artists using them for movie and video game content.

Variation of fracture pattern.

Variation of the surface-roughness for a fractured solid using the Boundary Element Method (BEM).

The first half of David's talk focused on the application of boundary element methods to simulate solid fractures, with examples of the variation in surface detail obtainable shown in the image above. The novel feature of their work is a separation of the computational mesh and the crack propagation, which leads to the crack-front being sampled at a higher resolution than the BEM mesh during crack propagation within the fracture.

These methods result in high resolution surface detail such as chevrons and sharp intersects, mimicking the surface roughness seen in real-life brittle fractures. The propagation of the crack front defines the fracture surface, and gives more realistic results than simply adding artificial noise during post-processing. Additionally, the method avoids unrealistic shattering effects which were an issue in previous simulations, and also takes into account spatial variation of toughness within the material.

Institute of Science and Technology Austria.

Institute of Science and Technology Austria.

Moving away from solid fractures, David introduced an interesting surface-only method for the simulation of incompressible fluid flows with surface tension in three directions; including discussion of the projection method used to keep the solution divergence free. A range of different fluid animations were presented, such as dripping water, the collision of two water jets, and the interaction of a water droplet landing on a hydrophobic surface.

Further information on both surface fractures and fluid interactions can be found on the Wojtan group website.