Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The sloshing dynamics are typically represented by a mechanical model of a spring–mass–damper system. This mechanical model is then included in the equation of motion of the entire vehicle for guidance, navigation and control analysis. The typical parameters required by the mechanical model include the natural frequency of the sloshing, sloshing mass, sloshing mass center coordinates, and critical damping coefficient. During the 1960s in the U.S. space program, these parameters were computed either from analytical solutions for simple geometries or by experimental testing for the subscale configurations. The purpose of this work is to demonstrate the soundness of a computational-fluid-dynamics approach in modeling the detailed fluid dynamics of tank sloshing and the excellent accuracy in extracting mechanical properties for different tank configurations and at different fill levels. As the first attempt, the...