A Sloshing FSI CFD simulation is a computer model that studies how liquids moving inside a tank can affect the tank’s structure. This is very important for the safety of ships, like in an Oil Sloshing in a Tanker CFD analysis. When a ship moves, the oil inside sloshes around, creating powerful waves that hit the tank walls. This is a Fluid-Structure Interaction (FSI) problem because the fluid’s force affects the structure, and the structure’s movement can affect the fluid. An Oil Sloshing in a Tanker Fluent simulation uses the Volume of Fluid (VOF) model to track the oil’s free surface. This is then coupled with ANSYS Mechanical via system coupling fluent in a Two-Way FSI Simulation to calculate the stress and deformation on the tank walls. This helps engineers design safer tankers that can handle the strong forces from sloshing. For more advanced FSI tutorials and fluid-structure interaction examples, explore our comprehensive collection at CFDLAND FSI Simulations.

Figure 1: The 3D geometry of the oil tanker section used for the Sloshing FSI Fluent simulation, including internal support structures.

Simulation Process: ANSYS FSI Setup, Coupling Fluent VOF with Mechanical for Sloshing Analysis

To perform this Sloshing FSI CFD simulation, a realistic 3D model of the oil tanker was created. The geometry included the main cylindrical tank sections and the internal support structures, which are very important for the tank’s strength. The structural parts of the model were meshed with high-quality elements and defined with the material properties of structural steel in ANSYS Mechanical. This ensures the stress and deformation predictions are accurate.

The simulation used a two-way FSI approach, which means ANSYS Fluent and ANSYS Mechanical were solved together and exchanged data continuously. To create the sloshing motion, a special mathematical expression was used to make the whole tank move. Inside Fluent, the Volume of Fluid (VOF) model was activated. A critical part of the setup was using the Dynamic Mesh feature in Fluent. As the tank walls deform from the fluid’s force, the mesh inside the fluid domain must stretch and move with it. The dynamic mesh uses smoothing and remeshing methods to handle this movement without stopping the simulation or losing accuracy.

Figure 2: Geometry of Oil Tanker

Post-processing: FSI Analysis, Linking Fluid Impact Pressure to Structural Deformation and Stress

The structural results show the direct effect of this fluid impact. The total deformation contour in Figure 3 shows the tank wall bending outwards, with a maximum displacement of 3.8164e-7 meters at the end of the tank where the wave hits hardest. The elastic strain contour in Figure 4 shows how much the steel material is stretching, with a maximum strain of 7.861e-7 m/m. Both the deformation and strain are highest in the areas that line up with the fluid impact pressure, which proves the FSI coupling is working correctly.

Figure 3: Total deformation contours from the ANSYS Mechanical Stress Analysis, with the maximum displacement occurring at the tank end due to fluid impact.

Figure 4: Equivalent elastic strain contours, highlighting areas of material stretching under the sloshing load.

The simulation results provide a complete engineering story, showing exactly how the moving oil creates stress on the tank structure. This analysis connects the fluid dynamics to the structural response. First, the oil volume fraction contour in Figure 5 shows us the cause of the forces. At 1.5 seconds into the simulation, a large wave has formed, and the oil has piled up on one side of the tank. This creates a powerful impact and a large, unbalanced pressure on the tank wall. This is the sloshing load that the structure must be able to withstand.

The most critical result for an engineer is the von-Mises stress, shown in Figure 5. This contour shows where the internal forces in the material are highest. The maximum stress is 1.5637e5 Pascals, and it occurs at the connections between the tank wall and the internal support structures. This is expected, as these are points where the load path changes.

The most important achievement of this simulation is proving the tanker’s structural safety under the simulated sloshing conditions. The analysis shows that the maximum stress of 1.5637e5 Pa is very far below the yield strength of structural steel. This result, obtained through a validated two-way FSI model, gives engineers high confidence in the design. It successfully links the cause (fluid sloshing) to the effect (structural stress) and quantifies the response, confirming the tank is safe.

Figure 5: Oil volume fraction contours at 1.5 seconds, showing the asymmetric wave profile generated by the sloshing motion, as captured by the VOF Multiphase Fluent model.