FSI Analysis for a Ball in Water Flow, ANSYS Fluent CFD Simulation Training

Description

Description

The present problem simulates a spherical ball in water flow using ANSYS Fluent software using the FSI method.

The present model is designed in three dimensions using Design Modeler software. The model consists of a horizontal tube with a length of 0.02 m and a diameter of 0.001 m in which a spherical solid or ball with a diameter of 0.00009 m is placed.

We carry out the model’s meshing using ANSYS Meshing software. The element number is 20192.

Also, due to the nature of the present problem, the transient solver has been enabled.

Ball Methodology

We perform this simulation using FSI (fluid-solid interaction) method. In this simulation, a computational area is designed in the form of a horizontal tube filled with water flow; So that a solid or spherical object in the shape of a ball is immersed in it.

In such models, there is a need for instantaneous and time-dependent change in modeling the model based on the type of displacement at the adjacent mesh boundaries. In determining dynamic mesh methods, smoothing and remeshing methods have been used.

According to the smoothing method, the number of nodes does not change and only adjusts the mesh of an area by moving or deforming the boundaries. However, the remeshing method is used when the displacement of the borders is large compared to the size of the local cells to regenerate the destructive cells of the critical size limit.

To define areas with dynamic mesh, the pipe area is defined as stationary, and the wall around the ball is determined by system coupling with transient structural software. This means that the water flow location inside the pipe is constant relative to the ball, and the ball has no movement or rotation within the water flow.

The flow of water enters the tube at a speed equal to 0.001 m.s-1 and exits it at a pressure equal to atmospheric pressure. In the settings section of structural analysis software, the spherical body wall boundary is defined as fluid and solid interaction (fluid-solid interaction), i.e., this solid boundary can be affected by water flow behavior.

Then, it describes the type of data transfer between fluid and structural software in the system coupling section settings.

The definition of data transfer is defined from one boundary as a source in Fluent software to the same boundary as a target in Transient Structural software or vice versa in the form of a variable. For this simulation, two data transmissions are defined.

Thus, force is transferred from the fluid part to the structural part, and displacement is transferred from the structural part to the fluid region.

This means that the flow of water hits the spherical body with its movement, and the spherical body can also move inside the pipe. Moreover, the standard k-epsilon model is used to solve turbulent fluid equations.

Ball Conclusion

After the solution process, two-dimensional contours related to the pressure and shear stress on the surface of the body of the spherical body and two-dimensional contours related to the speed and pressure around the spherical body in the middle plate of the tube are obtained.

These contours correspond to the last second of the simulation process. Contours related to deformation and elastic strain are also obtained in the structural analysis section.