## 3 Simulation of the Regional Characteristics of a Bearing Flow Pattern
### Transition Characteristics of the Flow Pattern Region  
The rotational speeds and loads determine the film thickness distribution of the bearing, which in turn affects the Reynolds number of the pad. Figure 4 presents the simulation results obtained for the bearing performance under the four flow patterns at different rotational speeds. As shown in Figure 5a-c, when the rotational speed was less than 260 r/min, the minimum film thickness, power consumption, and inlet flow rate of the regional mixing flow pattern were close to those of the laminar flow pattern. When the rotational speed was greater than 360 r/min, the values almost coincided with those of the turbulent flow pattern. \begin{table}
\begin{tabular}{c c c c c} \hline
**Performance Parameters** & **Laminar Flow** & **Turbulent Flow** & **Node Mixing Flow Pattern** & **Regional Mixing Flow Pattern** \\ \hline \(\overline{W}\) & 0.45 & 0.73 & 0.91 & 0.70 \\ \(h_{min}\) (\(\mu\)m) & 21.31 & 27.23 & 25.79 & 23.60 \\ \(h_{z}\) (\(\mu\)m) & 33.01 & 42.12 & 46.91 & 41.07 \\ \(p_{max}\) * (MPa) & 1.19 & 1.19 & 1.19 & 1.17 \\ \(t_{max}\) * (\({}^{\circ}\)C) & 37.12 & 37.88 & 37.61 & 37.32 \\ \(N\) (kW) & 13.44 & 22.59 & 22.55 & 17.73 \\ \(Q_{in}\) (\(\times 10^{-4}\) m\({}^{3}\)/s) & 1.14 & 1.41 & 1.55 & 1.28 \\ \(\delta\)(r,\(\theta\)) (\(\mu\)m) & 3.94 & 4.97 & 4.58 & 4.24 \\ \hline \end{tabular}
\end{table} 
Table 2: The lubrication performance obtained under four kinds of flow state modes (300 r/min, 0.5 MPa). Figure 4: Zone map of the mixing flow pattern (300 r/min, 0.5 MPa). As shown in Figure 5d, the laminar and turbulent areas are on the lower right and upper left corners of the figure, respectively. With the increase in the rotational speeds, the laminar flow area gradually decreased, and the turbulent flow area increased. When the rotational speed was 320 r/min, the turbulent area was 57.6 times greater than that at 260 r/min. When the rotational speed was 340 r/min, only a few areas were laminar flow areas. The bearing performance was between that of the laminar and turbulent flows when it was in the regional mixing flow pattern. A single flow pattern cannot reflect the phenomenon of the flow pattern changing with the changing speed. Thus, it is more reasonable to apply the regional mixing flow pattern to the bearing design under variable operating conditions. Figure 6 presents the simulation results obtained for the bearing performance under the four flow pattern modes at different specific pressures. As shown in Figure 6a-c, the minimum film thickness, power consumption, and inlet flow rate of the regional mixing flow pattern were close at first to those of the turbulent flow and then gradually became more similar to those of the laminar flow with the increase in the specific pressure. There was a fluctuation between specific pressures of 0.6 and 0.7 MPa, as shown in Figure 6b, for the node mixing flow pattern. The Reynolds number of each node was calculated, and each \(G_{\theta}\) and \(G_{r}\) of the laminar and turbulence flows were substituted into Equation (2). Since \(G_{\theta}\) and \(G_{r}\) were 1/12 in the laminar flow and obtained by Equation (3) in the turbulent flow, the values were not continuous, which led to the discontinuity of \(h\) and \(\mu\). According to Equation (9), the power loss of the pad is determined by these two important parameters. As a consequence, there is a fluctuation as the specific pressure increases. As shown in Figure 6d, when the specific pressure was between 0.3 and 0.7 MPa, the bearing interface was in the mixing flow, and the bearing performance should be between that of the laminar and turbulent flows. With the increase in the specific pressure, the turbulent flow area decreased gradually; that is to say that although the bearing flow pattern was close to a full turbulent flow under a light load, the heavy load made the flow pattern change to a laminar flow.