"Smoothing out HLLC's 'carbuncles' in Fluid Shock Simulations"

This is a research project I did over the summer as a part of the Princeton Astrophysics Department's "Undergraduate Summer Research Program" (USRP). I ran various fluid shock simulations using RAMSES, a fluid simulation software written by Romain Teyssier, a fluid dynamicist and cosmologist who was my advisor for this summer project.

During the development of this project, I ran computational fluid dynamics simulations written in Fortran, modified and tested various initial conditions, batched simulations using bash/slurm scripts to Princeton's Adroit and Stellar supercomputer clusters, and visualized the data using Python to produce my final presentation and paper (written in LaTeX).

I identified the "carbuncle" instability present in the HLLC Riemann solver, quantified their growth rate through testing (creating a model for the carbuncles' growth over time and how that growth scales with resolution), and developed a fix for the carbuncles by introducing an error correction factor θ to HLLC, creating a new Riemann solver: LHLLC. You can hear or read more about it in the video presentation and paper linked below.

I've also included a higher-resolution version of the final comparison at the end of my presentation, as it's a little hard to see in the video.

If the either the video or paper is not loading for you, you can download the video as an mp4 or download the paper as a pdf if you'd like.