## 5 Calculations in a Universal CFD Program
### Optimization of the Maximum Load Capacity of the Bearing
At points corresponding to higher angle values, the load capacity decreased. At low eccentricities (0.05-0.15), the load capacity did not exceed 20 N, reaching maximum values around angles of 320\({}^{\circ}\)-330\({}^{\circ}\). * The reaction force in the X direction (Figure 8c,d) for eccentricities in the range 0.05-0.15, with the journal positioned at an angle of 270\({}^{\circ}\), varied from 8 N to 17 N. Around an angle of 340\({}^{\circ}\), it reached zero, and at the end of the analyzed interval (360\({}^{\circ}\)), it took negative values, reaching \(-\)4 N.  
Figure 7: Load capacity maps of the gas-dynamic bearing for given input parameters: (**a**) in the Y direction; (**b**) in the X direction. * For higher eccentricities, the curves depicting the reaction force in the X direction were sinusoidal. The highest value of the reaction force in the X direction occurred around angles 285\({}^{\circ}\)-290\({}^{\circ}\) and was approximately 34 N at an eccentricity of 0.35. The lowest value of the reaction force in the X direction was \(-\)34 N (negative value) and occurred near angles of 350\({}^{\circ}\)-355\({}^{\circ}\). The reaction force in the X direction reached zero in the angle range of 310\({}^{\circ}\)-340\({}^{\circ}\). These results provide an understanding of the effect of relative eccentricity and angle on the reaction forces of the lubricating film. Knowledge of these relationships can be useful when designing slide bearings and optimizing their tribological properties. Analysis of the pressure distribution in the bearing showed that a gaseous lubricating wedge had formed in the angle range 260\({}^{\circ}\)-310\({}^{\circ}\), which corresponded to an elevated pressure of approximately 1.1 \(\times\) 105 Pa (absolute pressure). However, on the opposite side of the journal, in the angle range 45\({}^{\circ}\)-105\({}^{\circ}\), a region of lowest pressure was formed, with a value of approximately 0.93 \(\times\) 105 Pa. The areas of highest and lowest pressure were in the plane of symmetry of the bearing, i.e., in its central part. In the medium outlet plane (at the edge of the bearing), the pressure value was 1.0 \(\times\) 105 Pa (1 bar) and remained constant. The pressure distribution in the bearing is presented in Figure 9.  
The analysis of velocity lines (Figure 10a) and velocity vectors (Figure 10b) in the gas-dynamic bearing allows for a better understanding of the phenomena occurring inside the bearing. At the edges of the bearing, the velocity of the lubricant was close to zero (approximately 0.01 m/s). This is due to the so-called adhesion effect, where the gas molecules adhere to the bearing walls, forming a boundary layer. This is a phenomenon  
Figure 8: Changes in the reaction force of the lubrication film in the gas-dynamic bearing: (**a**) in the Y direction for selected eccentricities vs. journal position angle; (**b**) in the Y direction for selected angles vs. relative eccentricity; (**c**) in the X direction for selected eccentricities vs. journal position angle; (**d**) in the X direction for selected angles vs. relative eccentricity. typical of laminar flow, as is the case with gas bearings. The maximum velocity of the lubricating medium (102 m/s) occurred at the center of the bearing, close to the journal wall. This increase in velocity at the center of the lubrication gap is due to the greatest distance between the walls, making the flow resistance the smallest. The region of constant velocity in the center of the bearing suggests that this area is unaffected by boundary effects, such as the adhesion of the lubricating medium to the bearing walls. The following phenomena were observed in the analysis of the velocity vectors in the axial direction (Figure 10b): At the lower part of the bearing, where there was a high-pressure area, the lubricating medium left the bearing space. The high pressure causes gas to be forced out of the lubrication gap, which is important for maintaining the load capacity of the lubricating film.