*4.2. Turbulent Inflow*

This section presents the simulation results from the AD and AS cases under the fully developed turbulent inflow condition.

#### 4.2.1. Instantaneous Flow Field

Figure 5 depicts instantaneous velocity fields computed from (a) the AD and (b) the AS models and (c) the inflow case on the *z* = *z*hub plane at the same instant. As seen, the wake shapes and the spanwise velocity contours from the AD and AS cases show a reasonably good agreement, except for some differences, such as the jet flow behind the hub of the AS model. Compared with the uniform inflow condition, strong effects of inflow turbulence is observed. For instance, a much stronger spanwise velocity is observed for the turbulent inflow (Figure 5d,e) when compared with that from the uniform inflow (Figure 2c,d). When comparing with the only inflow case (Figure 5f), we can observe an interesting phenomenon, that the patterns of the spanwise velocity computed from the AD and AS model, are very similar to that from the only inflow case. Moreover, it is noticed that both AD and AS models amplify the spanwise velocity fluctuations as the velocity magnitude is larger in the wake than in the inflow. Apart from this, no more information can be extracted with confidence from this instantaneous flow field yet.

**Figure 5.** Turbulent inflow: contours of the instantaneous velocity field behind the wind turbine on the horizontal plane at hub height. (**a**) streamwise velocity using AD; (**b**) streamwise velocity using AS; (**d**) spanwise velocity using AD; (**e**) spanwise velocity using AS. The solid black line at *x* = 0 illustrates the location and the diameter of the wind turbine; (**c**,**f**) streamwise and spanwise velocity of the turbulent inflow without wind turbine.
