Turbulent fluid dynamics are often too complex to model every detail. Instead, we tend to model bulk quantities and low-resolution approximations. To remain physical, these reduced approximations of the Navier-Stokes equations must be "closed", and turbulence closure modeling is one of the most important topics in high-performance computing and scientific computing. This video describes several leading approaches, including the Reynolds averaged Navier Stokes (RANS) equations and large eddy simulations (LES). Citable link for this video: https://doi.org/10.52843/cassyni.cjkr7f @eigensteve on Twitter eigensteve.com databookuw.com This video was produced at the University of Washington