# Influence of Inflow Turbulence on the Flow Characteristics around a Circular Cylinder
## 3 Characteristic Parameters of Mean Wind Pressure Coefficient Distribution
### In the Turbulent Flow  
In order to further analyze the influence of turbulence intensity and the Reynolds number on certain factors, the following are plotted in Figures 9-13: the characteristics of wind pressure distribution on the circular cylinder surface, the mean wind pressure coefficient within the base region \(C_{pb}\), the angular position of where the base region starts \(\theta_{b}\), the minimum wind pressure \(C_{pm}\), the angular position of minimum wind pressure coefficient \(\theta_{m}\) and the wind pressure rise coefficient \(C_{pb}\)-\(C_{pm}\) of different turbulent flows and Reynolds numbers. Figure 8: Wind pressure rise coefficient (\(C_{ph}\)-\(C_{pm}\)) in the smooth flow. Figure 9: The mean wind pressure coefficient within the base region \(C_{pl}\) in turbulent. Figure 9 shows \(C_{pb}\) of different turbulent flows and Reynolds numbers. In the smooth flow, \(C_{pb}\) increases with the increase in Reynolds number, and \(C_{pb}\) is basically unchanged in the supercritical regime. In the turbulent flow, \(C_{pb}\) increases first and then decreases with the increase in Reynolds number. When the Reynolds number is less than \(1\times 10^{5}\), \(C_{pb}\) increases with the increasing turbulence intensity. There is no significant difference between \(C_{pb}\) in different turbulent flows when the Reynolds number is larger than \(2\times 10^{5}\). When the turbulence intensity is larger than \(8\%\), \(C_{pb}\) in all regimes is basically the same at the same Reynolds number. In the supercritical regime, \(C_{pb}\) in the smooth flow is larger than the \(C_{pb}\) under turbulence. Figure 11: Minimum wind pressure coefficient \(C_{pm}\) in turbulent flow. Figure 10: The angular position of where the base region starts \(\theta_{b}\) in the turbulent flow. Figure 10 shows \(\theta_{b}\) for different turbulence intensities and Reynolds numbers. In the smooth flow, \(\theta_{b}\) is about \(80^{\circ}\) in the subcritical regime, suddenly moves backwards in the critical regime and it is basically stable at \(140^{\circ}\) in the supercritical regime. In the turbulent flow, \(\theta_{b}\) is about \(140^{\circ}\) in the measured Reynolds number regime and is independent of the turbulence intensity. When the Reynolds number is in the supercritical regime, \(\theta_{b}\) in the smooth flow and the turbulent flows are both approximately \(140^{\circ}\)--that is, in the supercritical regime. The position of the flow separation point is then basically independent of the flow state. Figure 12: The angular position of minimum wind pressure coefficient \(\theta_{m}\) in the turbulent flow. Figure 13: Wind pressure rise coefficient \(C_{pl}\)-\(C_{pm}\) in the turbulent flow. Figure 11 shows \(C_{pm}\) for different turbulence intensities and Reynolds numbers. In the smooth flow, \(C_{pm}\) is almost unchanged in the subcritical regime and suddenly decreases in the critical regime. However, it changes little in the supercritical regime. In the turbulent flow, when the Reynolds number is less than \(2\times 10^{5}\), \(C_{pm}\) decreases with the increasing Reynolds number and decreases with stronger turbulence intensity at the same Reynolds number. When the Reynolds number is larger than \(2\times 10^{5}\), \(C_{pm}\) has very minor changes. When the Reynolds number is greater than \(3.3\times 10^{5}\), \(C_{pm}\) is basically unchanged and is close to the value in the smooth flow. Figure 12 shows \(\theta_{m}\) for different turbulence intensities and Reynolds numbers. In the subcritical regime, turbulence leads to an increase of \(\theta_{m}\). In every turbulent flow in this paper, within the regime of measured Reynolds number, \(\theta_{m}\) is basically unchanged when the Reynolds number reaches a certain value--such as \(1.9\times 10^{5}\)--in turbulent flows of \(8\%\) and \(12\%\). There is a significant difference in \(\theta_{m}\) when the Reynolds number is between \(1\times 10^{5}\) and \(3\times 10^{5}\).