I’ve been running some simple test cases and I’ve come across an unexpected AeroDyn hub load.
I’ve started with the Cert Test 25 as a base model and then modified it in the following way:
- Analysis duration of 100 seconds
- Time step of 0.0125
- All modules disabled except:
a. All degrees of freedom disabled except 6 platform DoFs
b. No initial conditions - zero rotor speed.
c. Steady wind input, 8m/s no shear profile (PLexp=0)
d. TwrPotent = 0
e. TwrAero = False
f. Regular wave; WaveHs = 4, WaveTp = 14
g. WaveDir = 30
h. UnstrLen = 845.35 ( For all 3)
I ran this analysis in the 64bit double precision version of FAST 8.16 and plotted the hub load:
I then ran this analysis in the 64bit single precision version of FAST 8.16 and plotted the hub load:
I have a question and an observation about the above output:
- Is there any explanation for the sudden jumps in rotor hub load? (There is no sudden jump in displacement of the platform nor any warning/error that a problem has occurred)
- Except for the sudden jumps, the trend between the single and double precision versions is the same but the times that these jumps occur differ.
Thanks in advance!