MHK inflow calls

[hkross]

This pull request is ready to be merged.

Feature or improvement description

• Addresses minor bugs in calls to MHK inflow (wave+current)
• Sets all flow field kinematics below the seabed to zero
• Includes a few documentation updates

Impacted areas of the software

• AeroDyn
• SeaState
• Documentation

Test results

• r-test branch merging required

The following r-tests were impacted

1. ad_MHK_RM1_Floating: A node was querying the flow field out-of-bounds in the x direction. The flow field was expanded, thereby causing a slight phase shift in the x and z inflow velocities. The following plots compare the previous baseline (legend 0.0) with the new baseline (legend 0.1). As expected, peaks in the X direction loads see a corresponding phase shift.

2. MHK_RM1_Floating_Tank-scaled: This r-test used currents defined in SeaState rather than InflowWind. This pull request disallows the definition of currents in SeaState for MHK cases, so an equivalent current was defined in InflowWind instead. Prior to this pull request, flow field kinematics were non-zero below the seabed for flows defined in SeaState. This pull request improves consistency by zeroing all flow field kinematics below the seabed, regardless of the module in which they are defined. This effect can be seen in the following plots, where 0_SS uses a current defined in SeaState, with non-zero flow kinematics below the seabed, 1_SS uses a current defined in SeaState with zero flow kinematics below the seabed, and 1_IfW uses a current defined in InflowWind with zero flow kinematics below the seabed. The 1_SS and 1_IfW cases match, as defining a steady current in SeaState vs InflowWind gives an equivalent flow field. The 0_SS case sees higher anchor tensions, due to non-zero velocities seen by mooring line nodes at or below the seabed. Three platform motions are shown below, though the results are similar for all.

3. py_wavetank_test1: This r-test uses currents defined in SeaState and in InflowWind. It previously called the SeaState file from MHK_RM1_Floating_Tank-scaled. However, this SeaState file was updated to set the current to 0, and an equivalent current was defined in InflowWind. Because the SeaState pointer is not currently passed through the ADI c-bindings, wave-current coupling does not work properly when using the c-bindings (see Feature request: SeaState pointer passed into c-bindings #3315), so defining an equivalent current in InflowWind does not reproduce the baseline of the py_wavetank_test1 case. As a workaround, this pull request defines a separate SeaState file for the py_wavetank_test1 case that includes current. This change should be addressed when the SeaState pointer is integrated into the c-bindings, and the input files should be made consistent with the MHK_RM1_Floating_Tank-scaled test.

[luwang00]

Should we clarify this is the steady wind option in the AeroDyn driver (as opposed to in InflowWind) if that's what you meant?