PhD Final Oral Dissertation Defense: Criston Hyett, Program in Applied Mathematics

When

2 – 3 p.m., Aug. 26, 2025

Student:        Criston Hyett, Program in Applied Mathematics

Title:              Applications of Scientific Machine Learning in Fluid Dynamics

Advisor:         Misha Chertkov, Program in Applied Mathematics

Location:       Math building, Room 401 and zoom https://arizona.zoom.us/j/86262993084

Abstract:   Machine learning (ML) has ushered in a new age of mathematical modeling. Fluids, a ubiquitous component of engineering and fundamental research with high simulation cost, are a natural focus for efficient modeling using ML. This dissertation examines the application of structured ML from a physics-first perspective.

We present two differing applications of ML in fluids:

(1) The construction of a physics-informed, autoregressive ML model to close the equations of the Lagrangian velocity gradient tensor in isotropic turbulence. Besides improving the state-of-the-art, we interpret the model to uncover an interesting connection between the evolution of the pressure Hessian and the history of the strain-rate tensor.

(2) Using differentiable programming to perform PDE-constrained, (physics-adherent) optimization for contingency planning in natural gas networks. We empower network operators to utilize optimization with this proof-of-concept approach to unifying the gas flow simulator and optimizer.

Taken together, these applications show the potential of ML - appropriately applied - to advance understanding, increase fidelity, and enable engineering robustness. This work was advised by Dr. Misha Chertkov.