## UKCosmo Presentation, May 2019

I gave a blackboard talk at UKCosmo in May 2019. As I usually like to present movies and other visualisations when giving talks, I have collected that material (and key references and acknowledgments) here instead. The scanned notes for the talk are now available, and the final movies from the project are also online. The paper is also on arXiv.

## Collaborators

Our work on strong transitions is in collaboration with Mark Hindmarsh and Daniel Cutting. Earlier work has also involved Stephan J. Huber, Kari Rummukainen, and the broader LISA Cosmology Working Group.

## Visualisations

### Generation of vorticity

This movie shows a heatmap of vorticity ($$\nabla \times \mathbf{v}$$) during a strong deflagration ($$\alpha=0.5$$, $$v_w=0.44$$). Prepared from preliminary data supplied by Daniel Cutting, it shows several effects mentioned during the talk:

• The bubble walls slow as they get closer to each other.
• Reheated regions form in front of the bubble walls as the fluid kinetic energy gets stuck into smaller spaces.
• Vorticity is generated during the transition, as fluid is forced tangential to the direction of bubble expansion.

These effects are not seen in weaker transitions, or in detonations.

Direct links to video: MP4, webm.

### Other visualisations

Please visit my visualisations page or check out the Cosmic Defects channel on Vimeo or YouTube for more.