When water flows very fast around sharp objects, like the edge of a boat’s rudder or a hydrofoil, something amazing happens. The pressure can drop so low that the water starts to boil, even when it’s cold. This creates bubbles of water vapor, a phenomenon called cavitation. This is very important to study because these bubbles can change how the water flows and can even damage the equipment. In shallow water, it gets even more complex because both the water surface above and the ground below affect how these bubbles form and disappear. Using powerful computer tools called Computational Fluid Dynamics (CFD), we can watch this happen in a simulation. This is much cheaper and easier than building and testing real parts. Our study focuses on Cavitation Around Wedge CFD in shallow water, and we will check our results against a trusted research paper [1] to make sure our computer model is very accurate.

• Reference [1]: Xin, C. H. E. N., L. I. Jie, and C. H. E. N. Ying. “Properties of natural cavitation flows around a 2-D wedge in shallow water.” Journal of Hydrodynamics, Ser. B6 (2011): 730-736.

Figure 1: Reference plot from the paper [1] showing experimental Drag and Lift coefficients used for the Cavitation Around Wedge CFD VALIDATION.

Simulation Process: Modeling Three-Phase Flow in a Cavitating System

To correctly simulate the Cavitation Around Wedge Fluent problem, we first had to build a digital world that included three different things: the air above the water, the liquid water itself, and the water vapor created by cavitation. To track all three at once, we used a special tool in ANSYS Fluent called the Volume of Fluid (VOF) multiphase model. First, we drew our testing area with the wedge inside it using Design Modeler. We made sure to create a very neat grid of small boxes, called a structured grid, especially around the wedge (Figure 2). This helps the computer make very accurate calculations. The most important part of our setup was telling the computer how and when the water should turn into vapor. For this, we used a special rule called the Schnerr-Sauer cavitation model. This model acts as the brain for the wedge cavitation CFD simulation, controlling the mass transfer between liquid and vapor based on the local pressure.

Figure 2: The structured mesh around the wedge, designed for high accuracy in the wedge cavitation CFD simulation

Post-processing: Validating Hydrodynamic Forces and Visualizing the Cavity

Our simulation predicted a drag coefficient of 0.0712 and a lift coefficient of 0.0873. A major achievement of this Cavitation Around Wedge CFD VALIDATION study is the incredibly small error when compared to the reference paper [1]—just 0.28% for drag and 2.1% for lift. This near-perfect match proves that our simulation doesn’t just look right; it accurately predicts the real-world forces acting on the structure, which is the most critical information for designing safe and efficient marine hardware. This high level of accuracy gives engineers strong confidence to use this method to avoid the damaging effects of cavitation and improve the performance of underwater vehicles.

The simulation results tell a clear story of cause and effect, starting with the flow of water and ending with the forces on the wedge. The main cause of everything we see is the high-speed water being forced around the sharp wedge. The immediate effect is a pocket of low pressure behind it, which allows cavitation to happen. Figure 4 shows this perfectly. The red area is the vapor bubble, or “cavity,” that our simulation predicted. We successfully captured its exact teardrop shape and its length, which is a key sign that our Schnerr-Sauer model is working correctly. This vapor bubble and the fast flow shown in Figure 3 (the bright yellow streak) are the cause of the drag and lift forces on the wedge. The ultimate effect is revealed in our force calculations.

Figure 3: Velocity magnitude contour from the Cavitation Around Wedge Fluent simulation, showing flow acceleration and a high-speed jet.

Figure 4: Vapor volume fraction contour illustrating the Cavitation Around Wedge CFD process, showing the distinct vapor pocket formation behind the wedge.