Wave_load

[kristmro]

1. wave_loads.py -> deg2rad(rao_phase) #Roa_phase is in grad from the json file, and needs to be converted
   SOLUTION:
   

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 160 in 2362903

   phase = np.array(self._params["forceRAO"]["phase"])[:, :, :, 0]

   
   This needs to be changed to this:
   phase = np.deg2rad(np.array(self._params['forceRAO']['phase'])[:, :, :, 0])

2. wave_loads.py -> tau_sv = self.second_order_loads(time, eta[-1]) #Changed from eta[-2] to eta[-1]
   SOLUTION:
   

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 149 in 2362903

   tau_sv = self.second_order_loads(time, eta[-2])

   
   This needs to be changed to this:
   tau_sv = self.second_order_loads(time, eta[-1])

3. wave_loads.py -> change from + to - in second second_order_loads for self._P -- Aligns with wf loads
   SOLUTION:
   

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 267 in 2362903

   self._amp @ (Q * np.exp(self._W * (1j * t) + 1j * self._P)) @ self._amp

   
   This and the line over and under needs to be:

tau_sv = np.real(self._amp@(Qnp.exp(self._W(1jt) - 1jself._P))@self._amp)

Credz Håkon bakke

[incebellipipo]

Can you please provide the reasons for those changes? You can reference the relevant equations from books or research articles if possible.

[kristmro]

1. Printing the values one gets from the phase one can see that it is in degrees. In orca you can choose the output: Orca documentation
   This needs to be in rad because of the calculations that follow, e.g. that the frequency is in rad/s and here:
   

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 223 in 2362903

   - rao_phase

   
   were the trigonometric functions expect angles in radians.

2. we need heading, and -2 is not heading. Just a typo, can be shown most easily with what the function excepts as an input:
   

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 230 in 2362903

   def second_order_loads(self, t, heading):

3. (Hygen, 2023) In the equations 2.37 and 2.38 describe Jan-Erik Hygen how he intended the formula to be, but in equation 4.9 he wrote with a positive sign as he also did in

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 267 in 2362903

   self._amp @ (Q * np.exp(self._W * (1j * t) + 1j * self._P)) @ self._amp

   
   for me, it seems like a mismatch. I think Håkon Bakke also made a point about the first and second forces needing to be in phase with each other. I think he is referring to how the first order is calculated with

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 223 in 2362903

   - rao_phase

   being negative. I will ask him to comment here to specify better. However, it might be wise to contact Roger about this because in this paper Yue & Dick ,1989 the phase is left out when calculating the sv drift forces for a unidirectional sea (equation 5). This might be, without analyzing it thoroughly, because when taking the real of the equation, as done in

   mclsimpy/src/mclsimpy/waves/wave_loads.py

   Line 267 in 2362903

   self._amp @ (Q * np.exp(self._W * (1j * t) + 1j * self._P)) @ self._amp

   
   the phase will be gone or small enough to ignore. This further explains why having the phase in grad, instead of rad, did not affect the results.

[incebellipipo]

@rskjetne Can we have you input here

(Hygen, 2023) In the equations 2.37 and 2.38 describe Jan-Erik Hygen how he intended the formula to be, but in equation 4.9 he wrote with a positive sign as he also did in

mclsimpy/src/mclsimpy/waves/wave_loads.py

Line 267 in 2362903

self._amp @ (Q * np.exp(self._W * (1j * t) + 1j * self._P)) @ self._amp

for me, it seems like a mismatch. I think Håkon Bakke also made a point about the first and second forces needing to be in phase with each other, I will ask him to comment here to specify better. However, this might be wise to contact Roger about because in this paper Yue, Dick 1989 the phase is left out when calculating the sv drift forces for a unidirectional sea (equation 5).