"Numerical Investigation of Microgravity Sloshing Behavior in Confined Liquid Storage Using VOF Method"
- Paper ID
101790
- DOI
- author
- company
; University
- country
Türkiye
- year
2025
- abstract
Understanding liquid behavior in microgravity is crucial for space applications, particularly for rocket fuel tanks, space stations, and satellite fluid storage systems. Since gravitational forces are negligible in microgravity, fluid motion is primarily governed by surface tension, viscosity, and inertial forces. Traditional Earth-based sloshing models may not be valid in space, necessitating advanced numerical simulation techniques. This study employs Ansys Fluent to analyze sloshing behavior in a cylindrical tank under microgravity using the Volume of Fluid (VOF) model. The VOF approach accurately tracks the liquid-gas interface, making it ideal for capturing microgravity fluid behavior. Since surface tension forces dominate in low-gravity environments, the Brackbill Continuum Surface Force (CSF) model is implemented to ensure proper force calculations. Additionally, contact angle boundary conditions are set to model the interaction between the fluid and tank walls. Mesh resolution is a critical factor in these simulations. To accurately capture thin liquid layers and free surface motion, hexahedral or adaptive grids are typically used. To maintain stability, second-order spatial and temporal discretization schemes are preferred. Studies by W. J. Yang et al. (2019) demonstrated that a 3D grid with 50×50×25 cells provided adequate resolution for sloshing simulations. Because gravity in microgravity is extremely weak (e.g., 10⁻³g to 10⁻⁶g), liquids tend to adhere to container walls rather than settling at the bottom. Consequently, the low Bond number (Bo<1) condition must be considered. CFD simulations show that sloshing motion has lower amplitude and longer damping times compared to Earth-based conditions. Another key finding is the fluid distribution and “stickiness” effect in microgravity. Unlike Earth-based tanks, where liquid settles at the bottom, in microgravity, fluids may form thin layers along container surfaces, leading to unstable center-of-mass shifts. This effect can cause propellant loss and momentum changes in spacecraft. CFD simulations suggest that baffle (wave-damping) systems and thermocapillary forces can be used to mitigate these issues. in conclusion, microgravity sloshing simulations using Ansys Fluent and the VOF model provide valuable insights into fluid behavior in space. These studies contribute to optimizing spacecraft fluid propulsion systems, enhancing stability, and maximizing fuel efficiency.