Reduce dt do not increase the convergence of beamdyn

[QB-Lin]

I use AMR-Wind and OpenFAST for coupled simulation. The rotor is at the parked state, and the wind speed is close to 50 m/s. The inflow is turbulence, and the blade pitch angle is 90 deg.

I set the time step of AMR-Wind is 0.01 s, and that for OpenFAST is 0.001 s

The simulation terminated at t = 160 s:
"
terminate called after throwing an instance of 'std::runtime_error'
what(): FastIface: Error calling OpenFAST function:
FAST_Solution:FAST_UpdateStates:FAST_AdvanceStates:B1::BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after the maximum number of iterations
[s2200444:2067734] *** Process received signal ***
"

When I set the time step of OpenFAST to 0.0005 s

The simulation terminated at t = 90 s
"
what(): FastIface: Error calling OpenFAST function:
FAST_Solution:FAST_UpdateStates:FAST_AdvanceStates:B3::BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after the maximum number of iterations
[s2200444:2140700] *** Process received signal ***
"
The blade displacement and platform motion seem common

the wind load seems have large fluctuation

I saw that the decrease in time step tend to increase the convergence. But it failed for me.

[andrew-platt]

Dear @QB-Lin,

What versions of AMR-Wind and OpenFAST are you using? And which turbine model are you running?

Regards,

[QB-Lin]

Dear @andrew-platt

AMR-Wind 3.7.0
OpenFAST 4.1.2
IEA 15 MW UMaineSemi floating wind turbine
The yaw angle is 0 deg
The azimuth angle is 60 deg.

Regards,

[jjonkman]

Dear @QB-Lin,

Do you have a similar issue if you run the equivalent simulation in standalone OpenFAST (uncoupled from AMR-Wind), with InflowWind and AeroDyn enabled for the aerodynamic loads? It is probably easier to debug without the coupling to AMR-Wind.

Best regards,