Added tests for QTFs computed with RAFT and for MCF

- Added `test_calcQTF_slenderBody` in `test_fowt.py` that checks the QTFs computed with RAFT
- Modified tests/VolturnUS-S.yaml to compute the QTFs using the slender-body approximation and to use the MCF correction
- Besides the new QTF test, this commit affects the true values of test_analyzeCases (in test_model.py) and test_hydroExcitation (in test_fowt.py) for the test case VolturnUS-S.yaml. This is because the MCF correction affects the first-order loads and the second-order loads affect the response of the FOWT

tests/test_data/VolturnUS-S.yaml

@@ -1082,6 +1082,11 @@ platform:
 
     dlsMax       :  5.0     # maximum node splitting section amount for platform members; can't be 0
     potModMaster : 1
+    potSecOrder  :  1        # [int] master switch for computing second-order wave forces; 0=do not compute, 1=compute QTFs using slender body approximation, 2=read QTF file in WAMIT format (.11d or .12d)
+    min_freq2nd  :  0.040   # [Hz] minimum frequency for second-order wave forces
+    df_freq2nd   :  0.008   # [Hz] frequency step for second-order wave forces
+    max_freq2nd  :  0.200   # [Hz] maximum frequency for second-order wave forces
+
 
     members:   # list all members here
 
@@ -1092,6 +1097,7 @@ platform:
         shape     :  circ                      # [-]    circular or rectangular
         gamma     :  0.0                       # [deg]  twist angle about the member's z-axis
         potMod    :  False                     # [bool] Whether to model the member with potential flow (BEM model) plus viscous drag or purely strip theory
+        MCF       :  True
         # --- outer shell including hydro---
         stations  :  [0, 1]                    # [-]    location of stations along axis. Will be normalized such that start value maps to rA and end value to rB
         d         :  9.85                      # [m]    diameters if circular or side lengths if rectangular (can be pairs)
@@ -1115,6 +1121,7 @@ platform:
         shape     :  circ                      # [-]    circular or rectangular
         gamma     :  0.0                       # [deg]  twist angle about the member's z-axis
         potMod    :  False                      # [bool] Whether to model the member with potential flow (BEM model) plus viscous drag or purely strip theory
+        MCF       :  True
         # --- outer shell including hydro---
         stations  :  [0, 35]                    # [-]    location of stations along axis. Will be normalized such that start value maps to rA and end value to rB
         d         :  12.23                      # [m]    diameters if circular or side lengths if rectangular (can be pairs)

tests/test_fowt.py

@@ -283,6 +283,32 @@ def test_calcCurrentLoads(index_and_fowt):
 
     assert_allclose(D, desired_current_drag[index], rtol=1e-05, atol=1e-3)
 
+def test_calcQTF_slenderBody(index_and_fowt, flagSaveValues=False):    
+    # Set flagSaveValues to true to replace the true values file with the values calculated below    
+    index, fowt = index_and_fowt      
+
+    if fowt.potSecOrder: # Check only cases that compute the QTFs
+        true_values_file = list_files[index].replace('.yaml', '_true_calcQTF_slenderBody.pkl')
+
+        testCase = {'wave_heading': 30, 'wave_period': 12, 'wave_height': 6} # Testing one case only
+        fowt.calcHydroConstants() # Need to call this one before calcHydroExcitation
+        fowt.calcHydroExcitation(testCase, memberList=fowt.memberList) # Need to call this one before calcQTF_slenderBody
+        fowt.calcQTF_slenderBody(0) # Testing for the body considered to be fixed. Model class should take care of cases with motion
+
+        if flagSaveValues:
+            true_values={
+                'case': testCase,
+                'qtf': fowt.qtf,
+            }
+        else:
+            with open(true_values_file, 'rb') as f:
+                true_values = pickle.load(f)
+            assert_allclose(fowt.qtf, true_values['qtf'], rtol=1e-05, atol=1e-3)
+
+        if flagSaveValues:
+            with open(true_values_file, 'wb') as f:
+                pickle.dump(true_values, f)
+
 
 '''
  To run as a script. Useful for debugging.
@@ -305,3 +331,6 @@ def test_calcCurrentLoads(index_and_fowt):
     fowt = create_fowt(list_files[index])
     test_calcCurrentLoads((index,fowt))
 
+    fowt = create_fowt(list_files[index])
+    test_calcQTF_slenderBody((index,fowt))
+