OLAF FVW stability issue when simulating multiple rotors#3298
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luwang00 wants to merge 3 commits intoOpenFAST:rc-5.0.1from
Open
OLAF FVW stability issue when simulating multiple rotors#3298luwang00 wants to merge 3 commits intoOpenFAST:rc-5.0.1from
luwang00 wants to merge 3 commits intoOpenFAST:rc-5.0.1from
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Feature or improvement description
When simulating multiple rotors with the OLAF free vortex wake method, it was observed that the wakes of Rotor 2 and beyond tend to be unstable. This is most obvious immediately after the start of the simulation or when the global time step is large. The stability issue also does not manifest when running the standalone AeroDyn driver.
This problem appears to be fixed by calling
MV_AddModulefor the AeroDyn rotors inFAST_InitializeAllin reverse order, i.e., starting from the last rotor and ending with the first rotor. It is not yet clear why this change yields the desired behavior.Example results based on the r-test
MHK_RM1_Floating_MR:The code change does not affect the fluid torque of Rotor 1 (R1) significantly; however, the erratic torque fluctuation of R2 immediately following the start of the simulation disappears.
Impacted areas of the software
Glue-code
Test results, if applicable
This change affects r-tests with multiple rotors