Merge pull request #2937 from andrew-platt/b/FF_docs_issue1822

Docs update recomendations from issue #1822

Author: andrew-platt

docs/source/user/fast.farm/InputFiles.rst

@@ -167,12 +167,12 @@ low-resolution ambient wind data files must be named
 *Amb.t<n*\ :sub:`low`\ *>.vtk* and stored in a subdirectory named
 *Low*. In the file names, *<n*\ :sub:`low`\ *>* is an integer
 (without leading zeros) between *0* (at :math:`t=0`) and *N-1*, where
-:math:`N=FLOOR\left( \frac{TMax}{DT_\text{Low}} \right)+1` is the number
+:math:`N=FLOOR\left( \frac{\textbf{TMax}}{\textbf{DT_Low}} \right)+1` is the number
 of low-resolution time steps. The high-resolution ambient wind data
 files must be named *Amb.t<n*\ :sub:`high`\ *>.vtk*, where
 *<n*\ :sub:`high`\ *>* is an integer (without leading zeros)
 between 0 (at :math:`t=0`) and
-:math:`\frac{DT_\text{Low}}{DT\_High}\left( N-1 \right)`. The files must
+:math:`\frac{\textbf{DT_Low}}{\textbf{DT_High}}\left( N-1 \right)`. The files must
 be stored in a subdirectory named *HighT<n*\ :sub:`t`\ *>*, where
 *<n*\ :sub:`t`\ *>* is an integer (without leading zeros) between 1 and
 the total number of wind turbines (**NumTurbines**). Subdirectory
@@ -199,7 +199,7 @@ a prior simulation. If set to TRUE, FAST.Farm will check to ensure that:
    wind turbines. If there are more subdirectories, only the first
    **NumTurbines** will be used. If more files are in each subdirectory,
    only the first
-   :math:`\frac{DT_\text{Low}}{DT\_High}\left( N-1 \right)+1` will be
+   :math:`\frac{\textbf{DT_Low}}{\textbf{DT_High}}\left( N-1 \right)+1` will be
    used.
 
 -  The spatial resolution (number of grid points, origin, and spacing)
@@ -229,7 +229,7 @@ choose to use a time step that is an integer multiple smaller than or
 equal to **DT_Low**.
 When **Wake_Mod=2,3**, the stability of the algorithm will depend on the choice 
 of **dr** and **DT_Low**.
-(typically  :math:`DT_Low<dr/(2V_\text{Hub})`, 
+(typically  :math:`\textbf{DT_Low}<\textbf{dr}/(2V_\text{Hub})`,
 see :numref:`FF:ModGuidance`)
 
 
@@ -562,17 +562,17 @@ the wake meandering and must be greater than or equal to one. If the
 DEFAULT keyword is specified in place of a numerical value,
 **C_Meander** is set to :math:`1.9`.
 
-*----------------Curled wake parameters------------------*
-
 
+Curled wake parameters
+~~~~~~~~~~~~~~~~~~~~~~
 
 **Swirl** [switch] 
 Include swirl velocities in wake [only used if [**Mod_Wake=2**]
 or [**Mod_Wake=3**].
 
 **k_VortexDecay** [-] This constant specifies the decay rate of the 
 spanwise velocity components from the curled wake model. 
-DEFAULT is 0.0001.
+DEFAULT is 0.0.
 
 **NumVortices** [-] The number of vortices in the curled wake model. 
 DEFAULT is 100.

docs/source/user/fast.farm/ModelGuidance.rst

@@ -166,7 +166,7 @@ domain discretization criteria, discussed in :numref:`FF:sec:DiscRecs`.
 
 Additional wake dynamics quantities are needed when specifying the FAST.Farm
 input file, as discussed further in :numref:`FF:wake-dynamics-parameters`.
-It is recommended to base **dr** on :math:`c_\text{max}`;
+It is recommended to set **dr** to :math:`\le D^\text{Rotor} / 15`;
 **NumRadii** on wake diameter and **dr**; and **NumPlanes** on **DT_Low**,
 inflow hub-height velocity, and the distance between turbine locations.
 
@@ -515,8 +515,16 @@ time steps. Note that :math:`D^\text{Wake}` can be approximated as
 
 When **Wake_Mod=2,3**, for numerical stability, it is recommended to set the time step with a value that (approximately) satisfies the following guideline (see Equation 20 of the following `paper <https://doi.org/10.5194/wes-6-555-2021>`__):
 
+.. only:: html
+
+   .. math::
+      \textbf{DT_Low}  \lessapprox \frac{dr}{2 V_\text{Hub}}
+
+
+.. only:: not html
+
    .. math::
-      DT_Low  \lessapprox \frac{dr}{2 V_\text{Hub}}
+      \textbf{DT\_Low}  \lessapprox \frac{dr}{2 V_\text{Hub}}
 
 
 Spatial discretization convergence was assessed in the same manner as
@@ -531,16 +539,27 @@ denominator has the units [m/s]:
 
    .. math::
       \textbf{DS_Low} \le
-         \frac{C_\text{Meander}D^\text{Wake}V_\text{Hub}}{150 m/s}
-         = \frac{\textbf{DT_Low}V_\text{Hub}^2}{15 m/s}
+         \frac{C_\text{Meander}D^\text{Wake}V_\text{Hub}}{150~\text{m/s}} =
+         \begin{cases}
+            \frac{\textbf{DT_Low}V_\text{Hub}^2}{15~\text{m/s}}
+               & \qquad \text{for polar wake model} \\[0.5em]
+            \frac{C_\text{Meander}\textbf{DT_Low}V_\text{Hub}^2}{5~\text{m/s}}
+               & \qquad \text{for curled wake model}
+         \end{cases}
+         
 
 
 .. only:: not html
 
    .. math::
       \textbf{DS\_Low} \le
-         \frac{C_\text{Meander}D^\text{Wake}V_\text{Hub}}{150 m/s}
-         = \frac{\textbf{DT\_Low}V_\text{Hub}^2}{15 m/s}
+         \frac{C_\text{Meander}D^\text{Wake}V_\text{Hub}}{150~\text{m/s}} =
+         \begin{cases}
+            \frac{\textbf{DT\_Low}V_\text{Hub}^2}{15~\text{m/s}}
+               & \qquad \text{for polar wake model} \\[0.5em]
+            \frac{C_\text{Meander}\textbf{DT\_Low}V_\text{Hub}^2}{5~\text{m/s}}
+               & \qquad \text{for curled wake model}
+         \end{cases}
 
 
 For all synthetic turbulence methods, it is recommended that
@@ -816,12 +835,14 @@ parameters:
    suggested:
 
    .. math::
-      \textbf{dr} \le c_\text{max}
+      \textbf{dr} \le D^\text{Rotor} / 15
 
-When **Wake_Mod=2,3**, for numerical stability, it is recommended to set the spacing with a value that (approximately) satisfies the following guideline (see Equation 20 of the following `paper <https://doi.org/10.5194/wes-6-555-2021>`__):
+When **Wake_Mod=2,3**, for numerical stability, it is recommended to set the
+spacing with a value that (approximately) satisfies the following guideline (see
+Equation 20 of the following `paper <https://doi.org/10.5194/wes-6-555-2021>`__):
 
    .. math::
-      \textbf{dr}  < \frac{D}{10}
+      \textbf{dr} \le D^\text{Rotor} / 15
 
 
 

glue-codes/fast-farm/src/FAST_Farm_IO.f90

@@ -816,7 +816,7 @@ SUBROUTINE Farm_ReadPrimaryFile( InputFile, p, WD_InitInp, AWAE_InitInp, OutList
    !----------------------- CURL WAKE PARAMETERS ------------------------------------------
    CALL ReadCom        ( UnIn, InputFile, "Section Header: Curl wake parameters", ErrStat2, ErrMsg2, UnEc ); if(failed()) return
    CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%Swirl        ,    "Swirl", "Swirl switch", .True., ErrStat2, ErrMsg2, UnEc); if(failed()) return
-   CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%k_VortexDecay,    "k_VortexDecay", "Vortex decay constant", 0.0001, ErrStat2, ErrMsg2, UnEc); if(failed()) return
+   CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%k_VortexDecay,    "k_VortexDecay", "Vortex decay constant", 0.0, ErrStat2, ErrMsg2, UnEc); if(failed()) return
    CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%NumVortices,      "NumVortices", "Number of vortices in the curled wake", 100, ErrStat2, ErrMsg2, UnEc); if(failed()) return
    CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%sigma_D,          "sigma_D", "Gaussian vortex width", 0.2, ErrStat2, ErrMsg2, UnEc); if(failed()) return
    CALL ReadVarWDefault( UnIn, InputFile, WD_InitInp%FilterInit,       "FilterInit", "Filter Init", 1 , ErrStat2, ErrMsg2, UnEc); if(failed()) return
@@ -1026,9 +1026,9 @@ SUBROUTINE Farm_ValidateInput( p, WD_InitInp, AWAE_InitInp, ErrStat, ErrMsg )
    IF (WD_InitInp%NumRadii < 2) CALL SetErrStat(ErrID_Fatal,'NumRadii (number of radii) must be at least 2.',ErrStat,ErrMsg,RoutineName)
    IF (WD_InitInp%NumPlanes < 2) CALL SetErrStat(ErrID_Fatal,'NumPlanes (number of wake planes) must be at least 2.',ErrStat,ErrMsg,RoutineName)
 
-   IF (WD_InitInp%k_VortexDecay < 0.0_ReKi) CALL SetErrStat(ErrID_Fatal,'k_VortexDecay needs to be postive',ErrStat,ErrMsg,RoutineName)
-   IF (WD_InitInp%NumVortices < 2) CALL SetErrStat(ErrID_Fatal,'NumVorticies needs to be greater than 1',ErrStat,ErrMsg,RoutineName)
-   IF (WD_InitInp%sigma_D < 0.0_ReKi) CALL SetErrStat(ErrID_Fatal,'sigma_D needs to be postive',ErrStat,ErrMsg,RoutineName)
+   IF (WD_InitInp%k_VortexDecay < 0.0_ReKi) CALL SetErrStat(ErrID_Fatal,'k_VortexDecay must be >= 0',ErrStat,ErrMsg,RoutineName)
+   IF (WD_InitInp%NumVortices < 2) CALL SetErrStat(ErrID_Fatal,'NumVorticies must be greater than 1',ErrStat,ErrMsg,RoutineName)
+   IF (WD_InitInp%sigma_D < 0.0_ReKi) CALL SetErrStat(ErrID_Fatal,'sigma_D must be postive',ErrStat,ErrMsg,RoutineName)
    IF (WD_InitInp%f_c <= 0.0_ReKi) CALL SetErrStat(ErrID_Fatal,'f_c (cut-off [corner] frequency) must be more than 0 Hz.',ErrStat,ErrMsg,RoutineName)
    IF (WD_InitInp%C_NearWake <= 1.0_Reki) CALL SetErrStat(ErrID_Fatal,'C_NearWake parameter must be greater than 1.',ErrStat,ErrMsg,RoutineName)
    IF (WD_InitInp%k_vCurl < 0.0_Reki) CALL SetErrStat(ErrID_Fatal,'k_vCurl parameter must not be negative.',ErrStat,ErrMsg,RoutineName)