This project focused on developing and validating a high-fidelity computational fluid dynamics (CFD) framework to simulate slosh dynamics of cryogenic fluids for space applications. Cryogenic propellants such as liquid hydrogen, oxygen, and methane are widely used in modern propulsion systems, but their behavior under low-gravity conditions presents significant challenges. In particular, fluid sloshing can impact vehicle stability, propellant management, and overall system reliability, making accurate predictive tools essential for future long-duration missions. The work was conducted using ANSYS Fluent and consisted of two primary phases: an isothermal model and a non-isothermal model incorporating phase change. In the first phase, a transient, multiphase Volume-of-Fluid (VOF) model was developed to simulate sloshing of liquid nitrogen in a cylindrical tank. A key contribution was the implementation of a custom “stepping method” to approximate experimentally derived acceleration profiles from drop tower testing. This approach enabled efficient and automated integration of time-varying acceleration into the simulation environment. Model validation was performed by comparing numerical results to experimental data from literature, as well as analytical solutions for slosh frequency. Free surface motion was tracked and analyzed using Fourier transforms to extract dominant sloshing frequencies. The model demonstrated strong agreement with analytical predictions, achieving approximately 5% error, establishing confidence in the numerical framework. In the second phase, the model was extended to include evaporation and condensation using Fluent’s built-in Lee model, along with heat transfer effects governed by the transient energy equation. Thermophysical properties were incorporated using external data sources, and multiple cases were evaluated by varying model coefficients. Pressure evolution within the tank was used as the primary performance metric, with pressure de