Berkeley Fluids Seminar
University of California, Berkeley
Bring your lunch and enjoy learning about fluids!
Wednesday, October 21, 2015
3110, Etcheverry Hall, 12:00-13:00
Daniel Lecoanet (Physics, Berkeley)
How Do We Know if a Simulation is Correct?
Fluid dynamics codes typically run a suite of test problems to demonstrate that they properly solve the fluid dynamics equations. One popular test problem is the Kelvin-Helmholtz (KH) instability, which determines if a code correctly captures mixing processes -- one of the most important physical mechanisms in fluid dynamics. We present KH simulations in Athena (finite-volume) and Dedalus (pseudo-spectral). For simulations with physical diffusion, both codes converge to the same reference solution. Simulations without physical diffusion are riddled with secondary instabilities which induce extra mixing. In this case, higher resolution simulations mix more than lower resolution simulations. Our converged solutions with physical diffusion mix the least. We discuss the implications for astrophysical simulations.