In many BSM physics scenarios the early Universe went through a first-order phase transition. The gravitational waves produced in the transition may be observable in future
gravitational wave detectors, such as the LISA gravitational wave space mission. In order to fully utilize the observations the  gravitational wave production must be calculated
to high precision.  In this talk I discuss the importance of numerical simulations in the analysis of phase transitions, from BSM thermodynamics, critical bubble nucleation and
the subsequent hydrodynamic evolution and gravitational wave production.

This talk is part of the Advancing gravitational wave predictions from cosmological first-order phase transitions