# Wind rose data¶

Here we demonstrate how mean results over wind rose data are calculated in `foxes`

. We need the following imports:

```
In [1]:
```

```
%matplotlib inline
import matplotlib.pyplot as plt
import foxes
import foxes.variables as FV
import foxes.constants as FC
```

First, we setup the wind farm. We choose 6 x 5 turbines on a regular grid:

```
In [2]:
```

```
farm = foxes.WindFarm()
foxes.input.farm_layout.add_grid(
farm=farm,
xy_base=[0.0, 0.0],
step_vectors=[[900.0, 50.0], [-80., 500.0]],
steps=[6, 5],
turbine_models=["NREL5MW", "kTI_05"],
verbosity=0
)
ax = foxes.output.FarmLayoutOutput(farm).get_figure(figsize=(4, 3))
plt.show()
```

Next, we create the states based on the static data file `wind_rose_bremen.csv.gz`

. The data represents a (coarse) wind rose with 216 states. Each of them consists of the wind direction and wind speed bin centres, and the respective statistical weight of the bin (normalized such that 1 represents 100%):

```
state,wd,ws,weight
0,0.0,3.5,0.00158
1,0.0,6.0,0.00244
2,0.0,8.5,0.00319
3,0.0,12.5,0.0036700002
4,0.0,17.5,0.00042
...
```

Let’s create the states object and have a look at the wind rose:

```
In [3]:
```

```
states = foxes.input.states.StatesTable(
data_source="wind_rose_bremen.csv",
output_vars=[FV.WS, FV.WD, FV.TI, FV.RHO],
var2col={FV.WS: "ws", FV.WD: "wd", FV.WEIGHT: "weight"},
fixed_vars={FV.RHO: 1.225, FV.TI: 0.05},
)
o = foxes.output.StatesRosePlotOutput(states, point=[0., 0., 100.])
fig = o.get_figure(16, FV.AMB_WS, [0, 3.5, 6, 10, 15, 20], figsize=(6, 6))
plt.show()
```

We can now setup our algorithm. In this example, we invoke one wake model for the wind deficit, `Bastankhah_linear`

(with linear wake superposition), and another for the turbulence intensity wake effect, `CrespoHernandez_max`

(with maximum wake superposition). Both obtain the wake growth parameter `k`

by a relation `k = 0.5 * TI`

, see `turbine_models`

choice in the wind farm setup. We use default partial wakes for both models, indicated py `partial_wakes=None`

:

```
In [4]:
```

```
algo = foxes.algorithms.Downwind(
farm,
states,
rotor_model="centre",
wake_models=["Bastankhah2014_linear", "CrespoHernandez_max"],
partial_wakes=None,
chunks={FC.STATE: 500, FC.POINT: 4000},
verbosity=0,
)
```

We can now calculate the results:

```
In [5]:
```

```
with foxes.utils.runners.DaskRunner() as runner:
farm_results = runner.run(algo.calc_farm)
o = foxes.output.FarmResultsEval(farm_results)
o.add_efficiency()
fig, axs = plt.subplots(2,1,figsize=(6, 7))
o = foxes.output.FarmLayoutOutput(farm, farm_results)
o.get_figure(fig=fig, ax=axs[0], color_by="mean_REWS", title="Mean REWS [m/s]", s=150, annotate=0)
o.get_figure(fig=fig, ax=axs[1], color_by="mean_EFF", title="Mean efficiency [%]", s=150, annotate=0)
plt.show()
o = foxes.output.FarmResultsEval(farm_results)
P0 = o.calc_mean_farm_power(ambient=True)
P = o.calc_mean_farm_power()
print(f"\nFarm power : {P/1000:.1f} MW")
print(f"Farm ambient power: {P0/1000:.1f} MW")
print(f"Farm efficiency : {o.calc_farm_efficiency()*100:.2f} %")
print(f"Annual farm yield : {o.calc_farm_yield(algo=algo):.2f} GWh")
```

```
[########################################] | 100% Completed | 102.10 ms
[########################################] | 100% Completed | 308.37 ms
Efficiency added to farm results
```

```
Farm power : 76.5 MW
Farm ambient power: 81.7 MW
Farm efficiency : 93.65 %
Annual farm yield : 670.45 GWh
```

Finally, we display the mean wind speed field as a 2D plot, including wake effects. We could simply do this by

```
o = foxes.output.FlowPlots2D(algo, farm_results)
o.get_mean_fig_xy(FV.WS, resolution=30)
plt.show()
```

This is perfectly fine, but if we wish to see a progress bar and have additional options for the parallel run on a cluster (which we are not using here), the output function should instead be passed to a `DaskRunner`

object:

```
In [6]:
```

```
with foxes.utils.runners.DaskRunner() as runner:
o = foxes.output.FlowPlots2D(algo, farm_results, runner=runner)
o.get_mean_fig_xy(FV.WS, resolution=30)
plt.show()
```

Note that for the vectorization/parallelization to work we need to set the `chunks`

arguments in the creation of the `Algorithm`

object. Here chunks of 4000 points were calculated at a time (for all states).