Flow field visualisation for particular flow conditions in v4

[fwasilcz]

Hi,
In v3 the calculate_horizontal_plane function allowed for specification of ws, wd and yaw angles.
In v4, the calculate_horizontal_plane function takes in the geometry parameters of the plane and findex_for_viz, which is supposed to be an int. How should I undestand this argument? Can someone explain or point me to some resource where I can read more about it?
I also tried using the method on fmodel with yaw implemented using set function, but it still produced the flow field for non-yawed conditions.
Regards
Filip

[misi9170]

Hi @fwasilcz ,

You can find documentation here, but this may not entirely answer your question. You can also look at #868, which is where the change was introduced---I've also added a few details there.

However, to summarize these (and they aren't the most clear, so certainly a summary is warranted!):

• In FLORIS v4, the user must set the wind conditions prior to the call to calculate_horizontal_plane.
• If only a single condition is set (i.e. one wind speed, one wind direction, one turbulence intensity, and one "row" of yaw angles (i.e. one yaw angle for each turbine)), then calculate_horizontal_plane() can be called without specifying findex_for_viz, and the single condition that was set will be used.
• The "findex" refers to the condition index
• If multiple conditions are set (i.e. multiple wind speeds, wind directions, etc), then the user may specify which to visualize in the call to calculate_horizontal_plane(). To specify the "first" condition, use findex_for_viz=0. This is also the default behavior if findex_for_viz is not passed. To specify the n th condition, use findex_for_viz=n.

You can also see this usage in examples/002_visualizations.py and the scripts in examples/examples_visualizations. These show the set being called for the desired wind condition, followed by the calculate_horizontal_plane() call. However, they do not demonstrate that you may set multiple conditions, and then select the one you wish to visualize by setting findex_for_viz, as you asked about.

[misi9170]

Here is an example script that utilizes the findex_for_viz argument. In making this based on examples/002_visualizations.py, I noticed that there is an incorrect comment in that example stating that the user must specify a single condition with set in order to run visualization routines. I will fix that in an upcoming pull request.

import matplotlib.pyplot as plt

import floris.layout_visualization as layoutviz
from floris import FlorisModel
from floris.flow_visualization import visualize_cut_plane


fmodel = FlorisModel("inputs/gch.yaml")

# Set the farm layout to have 8 turbines irregularly placed
layout_x = [0, 500, 0, 128, 1000, 900, 1500, 1250]
layout_y = [0, 300, 750, 1400, 0, 567, 888, 1450]
fmodel.set(layout_x=layout_x, layout_y=layout_y)

# For flow visualizations, the FlorisModel *may* be set to a single condition.
# Alternatively, multiple conditions may be set, if findex_for_viz is specified
# in the calculate_*_plane method.
fmodel.set(
  wind_speeds=[8.0, 8.0],
  wind_directions=[290.0, 200.0],
  turbulence_intensities=[0.06, 0.06]
) # Setting to findices (conditions)

horizontal_plane = fmodel.calculate_horizontal_plane(
    x_resolution=200,
    y_resolution=100,
    height=90.0,
    findex_for_viz=0, # Compute for the 0 findex (8.0 m/s, 290.0 deg, 0.06%)
)

# Plot the flow field with rotors
fig, ax = plt.subplots()
visualize_cut_plane(
    horizontal_plane,
    ax=ax,
    label_contours=False,
    title="Horizontal Flow with Turbine Rotors and labels (findex_for_viz=0)",
)


horizontal_plane = fmodel.calculate_horizontal_plane(
    x_resolution=200,
    y_resolution=100,
    height=90.0,
    findex_for_viz=1, # Compute for the 1 findex (8.0 m/s, 200.0 deg, 0.06%)
)

# Plot the flow field with rotors
fig, ax = plt.subplots()
visualize_cut_plane(
    horizontal_plane,
    ax=ax,
    label_contours=False,
    title="Horizontal Flow with Turbine Rotors and labels (findex_for_viz=1)",
)

plt.show()

running this produces a figure for each of the two conditions:

I did notice that there is a small "bug" in that, if you would like to also add turbine rotors to the image, plot_turbine_rotors uses the yaw angles from the 0th findex by default. The best approach here is to pass yaw_angles to plot_turbine_rotors (after a possible bit of manipulation).

[fwasilcz]

Thank you very much for your answer! Setting the conditions before calculating the plane worked very well.
Since I have a simulation with the entire windrose the findex_for_viz would be very painful to manage.

[misi9170]

You're right, working out the findex_for_viz would not be straightforward with a wind rose. Perhaps we will build some helper functions for that in future. In the meantime, I'm glad that setting the conditions beforehand is working as you need.