AD15: add nodal outputs for VUnd{xyz}i in global coords

[andrew-platt]

This PR is NOT ready for merging (more channel requests)

Feature or improvement description
Three new nodal outputs are added to AD15 for the undisturbed wind velocity at each blade node:

• VUndxi Undisturbed wind velocity at blade node in global X
• VUndyi Undisturbed wind velocity at blade node in global Y
• VUndzi Undisturbed wind velocity at blade node in global Z

These are particularly useful in checking the inflow into a blade on an OpenFAST turbine in a CFD coupled or FAST.Farm simulation. This feature was requested by @kshaler.

Example of data for the VUndxi channel for blade 1 (from the 5MW_Land_DLL_WTurb regression test case)

TODO

• convert channel doc pdf to .rst and update
• add blade nodal channels (auto generated sets):
  • induced velocity in global
  • disturbed wind in global
• regular outputs for (9 node ones):
  • all the above
  • VUndxi etc.

[jjonkman]

I agree that these outputs looks reasonable. If possible, it would also make sense to add the equivalent outputs for the tower (TwNβVUndxi, etc.) and for the disturbed wind at blade nodes (BαNβVDisxi, etc.). Also, the list of AeroDyn outputs in the documentation should be changed accordingly: https://openfast.readthedocs.io/en/main/_images/ad_output_channel.pdf (I have the Word version of this).

[ebranlard]

I would add potentially the induced velocity as well :)

[codecov-commenter]

Codecov Report

Merging #917 (9e002f8) into dev (a4d62ac) will decrease coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff             @@
##              dev     #917      +/-   ##
==========================================
- Coverage   11.17%   11.17%   -0.01%     
==========================================
  Files         211      211              
  Lines      310636   310648      +12     
  Branches   181308   181320      +12     
==========================================
  Hits        34722    34722              
- Misses     231795   231807      +12     
  Partials    44119    44119              

Flag	Coverage Δ
regtests	11.06% <0.00%> (-0.01%)	⬇️
unittests	2.57% <ø> (ø)

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Impacted Files	Coverage Δ
modules/aerodyn/src/AeroDyn_AllBldNdOuts_IO.f90	9.57% <0.00%> (-0.21%)	⬇️

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[ebranlard]

I would suggest to descope and merge this as it is :)

[andrew-platt]

Posted issue #1004 for the remaining items that were never completed. De-scoping this to what is thus far completed and merging (this backlog is ridiculous... mostly my fault though).