Sloshing Water in a Cube: Transitional motion

Sloshing Water in a Cube with Transitional Motion, ANSYS Fluent Training

Description

This project investigates the transitional motion of a cube containing water and air using ANSYS Fluent, examining how fluid sloshing develops as the container itself accelerates.

The fluid domain geometry was designed in Design Modeler, with the computational grid generated in ANSYS Meshing using an unstructured mesh totaling 168,367 elements.

Methodology

The interaction between water and air within the cube is modeled using the Volume of Fluid (VOF) multiphase approach, chosen for its efficiency and precision in capturing the interface location between phases — making it one of the most widely used methods for multiphase flow investigation due to its favorable computational cost.

The cube accelerates along the X-direction at 5 m/s², while gravitational acceleration acts along the -Y direction on the multiphase fluid. The simulation was run using an unsteady (transient) time solver.

Conclusion

This project models a simplified sloshing scenario relevant to fluid containers subjected to acceleration, such as those found in moving carrier vehicles — where similar sloshing behavior commonly occurs.

The results show that pressure on the cube's bottom surface varies systematically with position, increasing progressively further from the cube's front face. This trend reflects the fluid's inertial response to the applied acceleration: as the cube accelerates forward, water is driven toward the rear of the container, building up higher local pressure there. Gauge pressure at the bottom surface starts at 1290 Pa near the front and rises to a peak of 6500 Pa at the back face of the cube — a roughly five-fold increase that clearly demonstrates how translational acceleration reshapes the pressure distribution within a partially filled, sloshing container.