# Comprehensive Investigations on Fluid Flow and Cavitation Characteristics in Rotating Disk System
## 5 Conclusions  
The oil film between the friction disks processed with arranged hexahedral texture dimples is the research object in this study to analyze the oil flow behavior in the rotating disk system. The velocity and pressure of the oil film are solved using a finite difference algorithm, and the pressure coefficient of the flow field is calculated to predict the cavitation incipient position under different texture distribution densities. To simulate the cavitation process and verify the numerical analysis, a 3D model was created and calculated in CFX software (ANSYS, Canonsburg, PA, USA). The study results can be applied to cavitation prevention in instruments, such as hydro-viscous clutches, wet clutches, disk turbines, and disk motor cooling systems. This paper's research and summary are as follows.  
The mathematical model of the oil film is established based on Reynolds equation, and the oil film's velocity, pressure, and pressure coefficient are solved by finite difference algorithm. The results show that the hexahedral texture dimples change the velocity and pressure in the flow field. The oil's radial velocity is greater in the texture dimple than in the non-texture region. The cavitation area is confined to dimples at the outer diameter at lower texture densities. Cavitation occurs in the non-texture area at outer warp as the density of the texture distribution increases.  
ANSYS CFX was used to simulate the cavitation flow between the rotating disk system. The cavitation locations are found to be consistent with the numerical analysis' conclusions. When texture rate is low, a single isolated texture dimple causes a localized disturbance that affect the overall stability slightly. Experiments were used to confirm the above results and reach a consistent conclusion. The disturbance intensity in the boundary layer increases as the number of textures increases, resulting in cavitation in the non-texture region. It should be noted, however, that this is only applicable to the hexahedral texture. The cavitation performance of other texture types needs to be investigated further. The greater the texture depth, the smaller the cavitation volume fraction.  
Analysis of velocities of the vapor and liquid phases flowing through the texture cross-section and the flow inside the hexahedral texture dimple revealed that the flow  
Figure 32: Cavitation morphology on non-textured friction disk and textured friction disk ((**a**) is cavitation morphology on non-textured friction disk when speed is 350 rpm; (**b**) is cavitation morphology on non-textured friction disk when speed is 550 rpm; (**c**) is cavitation morphology on non-textured friction disk when speed is 1050 rpm; (**d**) is cavitation morphology on textured friction disk when speed is 350 rpm; (**e**) is cavitation morphology on textured friction disk when speed is 550 rpm; (**f**) is cavitation morphology on textured friction disk when speed is 1050 rpm; The arrows in (**c**) and (**d**) indicate the location of the cavitation bubbles).  
direction and flow pattern between the vapor and liquid phases remained essentially the same. Cavitation occurs when there is a low pressure and a high speed. Cavitation and pressure have an effect on one another. On the one hand, cavitation is more likely to occur in low-pressure areas because low pressure induces cavitation. Cavitation, on the other hand, results in a smaller low-pressure peak and a negative pressure. As a result, the cavitation effect is thought to enhance the dynamic pressure effect.