## 4 Simulation Results and Discussions
Furthermore, the maximum difference between the pressure values along the line of \(a_{1}\)-\(a_{2}\) and the line of \(b_{1}\)-\(b_{2}\) is only 0.9%, which is too small to ignore. That is because the distance between the line of \(a_{1}\)-\(a_{2}\) and the line of \(b_{1}\)-\(b_{2}\) is only 10 um. It can be considered that the flow characteristics are constant along the oil film thickness direction. So, the velocity magnitude and the turbulent intensity along the line of \(a_{1}\)-\(a_{2}\) are not mentioned again in this section. Figure 3:6 Pressure patterns of various OLDRs along the line of \(a_{1}\)-\(a_{2}\). (**a**) Node pressures of various OLDRs along the line of \(a_{1}\)-\(a_{2}\); (**b**) local enlarged view of I; (**c**) local enlarged view of II. Figure 3:7 Turbulent intensity patterns of various OLDRs along the line of \(b_{1}\)-\(b_{2}\). (**a**) Turbulent intensities of various OLDRs along the line of \(b_{1}\)-\(b_{2}\); (**b**) local enlarged view of I. To investigate the influence of various OLDRs on pressure distributions of the wall \(S\), the static pressure of the wall \(S\) for various OLDRs are calculated, as shown in Figure 3:8 It can be found that the maximum pressures are all located at the orifice zones (red circle zones in Figure 11). The ring-shaped high pressure located in the annular recess zone makes the oil film pressure more even, reflecting the pressure uniform effect of the annular recess. By comparing the annular pressures of various OLDRs, the annular pressure for different OLDRs decreases as in the sequence of OLDRs of 2, 3, 1, 4, 5, 0.5, 0.25. The influences of varying OLDRs on streamlines, the turbulent intensity, and the velocity magnitude of the fluid field along the orifice longitudinal sections (shown in Figure 11b) are simultaneously illustrated in Figure 3:9 As can be seen from these figures, the turbulent intensities at the oil inlet are all very low (about 0.07%, blue zones in Figure 12) for various OLDRs. In addition, the streamlines in the oil inlet zones are parallel and smooth for all OLDRs, presenting that the fluid field in the oil inlet zone is the laminar flow. After the high-pressure fluid passes through the orifice, two large vortices are formed in the annular recess. The two vortex centers are located near 56 mm and 60 mm along the Y direction, respectively. The left vortex rotates clockwise, and the right vortex rotates counterclockwise. The two vortices differ in the shape and the corresponding turbulent intensity. So, the zone of high turbulent intensity is not symmetrical with respect to the node position of 58 mm, as shown in Figure 12h. The maximum turbulent intensity is not located at the orifice center line, and decreases as in the sequence of OLDRs of 0.5, 0.25, 1, 2, 3, 4, 5. It is noted that the difference of the maximum turbulent intensity between OLDRs of 0.25 and 0.5 is 0.12%, presenting that the turbulent intensities for OLDRs of 0.25 and 0.5 can be regarded as the same. Furthermore, the second-order small vortices can be found in the annular recesses with all OLDRs except the OLDR of 2, and are located at the lower right corners of the annular recesses for the OLDRs of 0.25, 0.5, 1, 3 and at the lower left corners of the annular recesses for the OLDRs of 4 and 5. It had been reported that the small vibration of the hydrostatic bearing was mainly caused by the vortex and the vibration energy of the hydrostatic bearing increases with the strength of vortices [30; 31; 32]. Comparing the vortices of annular recesses with respect to various OLDRs, the OLDR of 2 has the minimum quantity of vortices and has the best ability to decrease the vibration and improve the stability of the bearing. It can be found from the aforementioned analyses that the fluid characteristics of the orifice-restricted hydrostatic thrust bearing are not absolutely symmetric with respect to the node position of 58 mm.