TFin: addressing review comments

docs/source/user/aerodyn/input.rst

@@ -326,7 +326,7 @@ The tail fin aerodynamics section contains two lines:
       ""           TFinFile     - Input file for tail fin aerodynamics [used only when TFinAero=True]
     ======  Tower Influence and Aerodynamics ============================================================= 
 
-**TFinAero** Flag to activate the tail fin aerodynamics calcualtion.
+**TFinAero** Flag to activate the tail fin aerodynamics calculation.
 
 **TFinFile** Path (absolute or relative to the AeroDyn input file) where the 
 tail fin input file is located. 
@@ -439,8 +439,9 @@ The tail fin outputs are:
 
  - TFinAlpha (deg):  Angle of attack          at the reference point of the fin
  - TFinDynP  (Pa):   Dynamic pressure         at the reference point of the fin
- - TFinRe     (-):   Reynolds number             at the reference point of the fin in the inertial coordinate system
- - TFinVrel   (m/s): Orthogonal relative velocity norm (:math:`V_{\text{rel},\perp}`)    at the reference point of the fin in the inertial coordinate system
+ - TFinM      (-):   Mach number              at the reference point of the fin
+ - TFinRe     (-):   Reynolds number          at the reference point of the fin
+ - TFinVrel   (m/s): Orthogonal relative velocity norm (:math:`V_{\text{rel},\perp}`)    at the reference point of the fin
  - TFinVdisxi (m/s): Disturbed velocity   (x)  at the reference point of the fin in the inertial coordinate system
  - TFinVdisyi (m/s): Disturbed velocity   (y)  at the reference point of the fin in the inertial coordinate system
  - TFinVdiszi (m/s): Disturbed velocity   (z)  at the reference point of the fin in the inertial coordinate system
@@ -822,7 +823,8 @@ An example of tail fin input file is given below:
     Comment
     ======  General inputs =============================================================
     1         TFinMod     - Tail fin aerodynamics model {0: none, 1: polar-based, 2: USB-based} (switch)
-    1.0       TFinArea    - Tail fin planform area (m^2) [used only when TFinMod=1]
+    0.5       TFinChord   - Tail fin chord (m) [used only when TFinMod=1]
+    0.3       TFinArea    - Tail fin planform area (m^2) [used only when TFinMod=1]
     10.,0.,0. TFinRefP_n  - Undeflected position of the tail fin reference point wrt the tower top (m)
     0.,0.,0.  TFinAngles  - Tail fin chordline skew, tilt, and bank angles about the reference point (degrees)
     0         TFinIndMod  - Model for induced velocity calculation {0: none, 1:rotor-average} (switch)
@@ -845,7 +847,7 @@ TFinMod is set to 1. (m^2)
 
 **TFinRefP_n** Undeflected position (:math:`x_{\text{ref},x_n},x_{\text{ref},y_n}, x_{\text{ref},z_n}`) of the tail fin from the tower top in nacelle coordinates.
 (formerly defined using ``TFinCPxn``,  ``TFinCPyn``, ``TFinCPzn``). 
-The distances defines the configuration for a furl angle of zero, and zero ``TFinAngles``.
+The distances defines the configuration for a furl angle of zero.
 For a typical upwind wind turbine, 
 :math:`x_n`, is positive downwind,
 :math:`y_n`, is positive to the left when looking downwind, and
@@ -891,6 +893,6 @@ between 1 and ``NumAFfiles`` and is only used when TFinMod is set to 1. (-)
 Unsteady slender body (USB) model inputs
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
-TODO
+This option is currently not available and will be documented in a future release.
 
 

docs/source/user/aerodyn/theory_tailfin.rst

@@ -165,7 +165,7 @@ Unsteady slender body model
 
 The unsteady slender body (USB) model is documented in :cite:`ad-hammam2022`.
 
+The theory will be implemented and documented in a future release.
 
-:red:`TODO`
 
 

docs/source/user/elastodyn/coordsys.rst

@@ -6,11 +6,73 @@ Coordinate systems
 
 For the coordinates system not detailed in subsections below, please refer to the following references:
 
--  `FAST 7 Manual <https://www.nrel.gov/docs/fy06osti/38230.pdf>`_
+- `FAST 7 Manual <https://www.nrel.gov/docs/fy06osti/38230.pdf>`_
+
+- `Technical report <https://www.nrel.gov/docs/fy04osti/34755.pdf>`_ on FAST_AD and modeling of the UAE wind turbine (in section 3)
 
 - :download:`FASTCoordinateSystems.doc <../../../OtherSupporting/ElastoDyn/FASTCoordinateSystems.doc>`:
-  Documents the transformation matrices relating each coordinate system in FAST. Unfortunately, there are no pictures in this document that diagram these coordinate systems. They can hopefully be visualized by means of the transformation matrices.
+  Documents the transformation matrices relating each coordinate system in OpenFAST. Unfortunately, there are no pictures in this document that diagram these coordinate systems. They can hopefully be visualized by means of the transformation matrices.
+
+.. _ed_rfrl_coordsys:
+
+Rotor-Furl coordinate system
+----------------------------
+The rotor-furl DOF allows the user to model the
+unusual configuration of a bearing that permits the
+rotor and drivetrain to rotate about the yawing-portion
+of the structure atop the tower. The rotor-furl DOF can
+alternatively be used to model torsional flexibility in
+the gearbox mounting if the rotor-furl axis is aligned
+with the rotor shaft axis. In order to include rotor-
+furling in the model, the user must designate the turbine
+as a furling machine by setting input ``Furling`` from the
+primary input file to True. Then, the user must assemble
+the furling input file, ``FurlFile``, and use the rotor-furl
+flag, RFrlDOF, to enable this feature.
+The angular rotor-furl motion takes place about the
+rotor-furl axis defined by inputs:
+``RFrlPnt_n``,
+``RFrlSkew``, and ``RFrlTilt``.
+available in FurlFile. 
+The input ``RFrlPnt_n`` locate an arbitrary point on the rotor-
+furl axis relative to the tower-top. Inputs ``RFrlSkew``
+and ``RFrlTilt`` then define the angular orientation of the
+rotor-furl axis passing through this point. 
+See :numref:`figTFAxes` for a schematic.
 
+The geometries of the hub and rotor-furl structure
+mass center, which are both components of the furling-
+rotor assembly, are defined relative to the tower-top as
+shown in :numref:`figTFFurl`.
+This definition was chosen in
+order to avoid having to define a coordinate system in
+the furling-rotor assembly since such a coordinate
+system would most likely have an obscure orientation,
+making it difficult for users to input configuration
+information relative to it. This definition also avoids
+the complications involved in having to define
+geometries differently, depending on whether or not a
+rotor-furl assembly exists separately from the nacelle,
+which depends on whether rotor-furl is present or
+absent in the turbine. 
+
+Since the component geometry of the furling-rotor
+assembly is defined relative to the tower-top, this
+geometry naturally changes with the rotor-furl angle.
+In order to avoid having to define different geometries
+for different rotor-furl positions (for example,
+variations in the initial rotor-furl angle), ElastoDyn expects
+the component geometry of the furling-rotor assembly
+to be defined/input at a rotor-furl angle of zero. As
+such, the initial rotor-furl angle does not affect the
+specification of any other rotor-furl geometry. Stated
+another way, the input geometries for the rotor-furl
+assembly components define the rotor configuration
+when the rotor-furl angle is zero regardless of initial
+rotor-furl position. Users should be clear of this
+convention when assembling their furling input file.
+
+.. _ed_tfrl_coordsys:
 
 Tail-Furl coordinate system
 ---------------------------
@@ -24,47 +86,12 @@ True. Then you must assemble the furling input file,
 ``FurlFile``, and use the tail-furl flag, ``TFrlDOF``, to enable
 this feature.
 The angular tail-furl motion takes place about the
-tail-furl axis defined by inputs ``TFrlPntxn``, ``TFrlPntyn``,
-``TFrlPntzn``, ``TFrlSkew``, and ``TFrlTilt`` available in
+tail-furl axis defined by inputs ``TFrlPnt_n``, ``TFrlSkew``, and ``TFrlTilt`` available in
 ``FurlFile``.
-Inputs ``TFrlPntxn``, ``TFrlPntyn``, and ``TFrlPntzn`` locate an arbitrary point on the tail-furl axis
+The input ``TFrlPnt_n`` locate an arbitrary point on the tail-furl axis
 relative to the tower-top. 
-Three angles ``TFinAngles`` define the angular orientation of the tail- furl axis passing through this point.  
 See :numref:`figTFAxes` for a schematic.
 
-The tail-furl bearing can be an ideal bearing with
-no friction by setting ``TFrlMod`` to 0; by setting
-``TFrlMod`` to 1, it also has a standard model that
-includes a linear spring, linear damper and Coulomb
-damper, as well as up- and down-stop springs, and up-
-and down-stop dampers. OpenFAST models the stop
-springs with a linear function of tail-furl deflection.
-The tail-furl stops start at a specified angle and work as
-a linear spring based on the deflection past the stop
-angles. The tail-furl dampers are linear functions of
-the furl rate and start at the specified up-stop and
-down-stop angles. These dampers are bidirectional,
-resisting motion equally in both directions once past
-the stop angle.
-
-A user-defined tail-furl spring and damper model
-is also available. To use it, set ``TFrlMod`` to 2 and
-create a subroutine entitled ``UserTFrl()`` with the
-arguments ``TFrlDef``, ``TFrlRate``, ``ZTime``, ``DirRoot``, and
-``TFrlMom``:
-
-- ``TFrlDef``: Current tail-furl angular deflection in radians (input)
-- ``TFrlRate``: Current tail-furl angular rate in rad/sec (input)
-- ``ZTime``: Current simulation time in sec (input)
-- ``DirRoot``: Simulation root name including the full path to the current working directory (input)
-- ``TFrlMom``: Tail-furl moment in N.m (output)
-
-The source file UserSubs.f90 contains a dummy
-``UserTFrl()`` routine; replace it with your own and
-rebuild OpenFAST. 
-Argument ``DirRoot`` may be used to write a record of
-what is done in ``UserTFrl()`` to be stored with the
-simulation results.
 
 The geometries of the tail boom mass center, tail
 fin mass center, and tail fin aerodynamic surface,