Dear Jason,

Thank you very for your kind reply.

The complete messages OpenFAST writes to the screen is very long, so I just attached the last print. You are right. The warning message of " no valid value of phi" happened frequently but not lead to software aborting. And I found that Vy became bigger and bigger. Finally, “Solution does not converge after the maximum number of iterations” leaded to software aborting.

FAST_Solution:FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 7, blade

1):BEMT_UnCoupledSolve:There is no valid value of phi for these operating conditions: Vx =

41.353, Vy = -1804, rlocal = 13.096, theta = 0.58614, geometric phi = 3.1187

BEMT_UpdateStates(node 8, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -33.154, Vy = -2583.1, rlocal = 15.379, theta = 0.55782, geometric phi

= -3.1288

BEMT_UpdateStates(node 9, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -87.492, Vy = -2991.5, rlocal = 17.661, theta = 0.53017, geometric phi

= -3.1124

BEMT_UpdateStates(node 10, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -121.12, Vy = -3029.9, rlocal = 19.941, theta = 0.50801, geometric phi

= -3.1016

BEMT_UpdateStates(node 11, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -132.92, Vy = -2696.7, rlocal = 22.218

FAST_Solution:FAST_AdvanceStates:BD_GA2:BD_DynamicSolutionGA2:Solution does not converge after

the maximum number of iterations

FAST_AdvanceStates:AD_UpdateStates:BEMT_UpdateStates(node 1, blade 1):BEMT_UnCoupledSolve:There

is no valid value of phi for these operating conditions: Vx = -12.852, Vy = -2612.4, rlocal =

2.3235, theta = 0.38558, geometric phi = -3.1367

BEMT_UpdateStates(node 2, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -47.774, Vy = -3219.8, rlocal = 2.9162, theta = 0.39557, geometric phi

= -3.1268

BEMT_UpdateStates(node 3, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -78.481, Vy = -3725.6, rlocal = 3.5058, theta = 0.40559, geometric phi

= -3.1205

BEMT_UpdateStates(node 4, blade 1):BEMT_UnCoupledSolve:There is no valid value of phi for these

operating conditions: Vx = -130.28, Vy = -4489.8, rlocal = 4.7989, theta = 0.436, geometric phi =

-3.1126

BEMT_UpdateStates(node 5, blade 1):BEMT_UnCoupl

FAST encountered an error at simulation time 0.2525 of 60 seconds.

Simulation error level: FATAL ERROR

Aborting OpenFAST.

Best regards,