Hi everyone,
I am trying to use standalone AeroDyn to simulate multi-rotor HAWT. The simulations teminated normally with wakeMod as BEM type but some error occured when I tried to model it with OLAF model. The errors are displayed below.
“ADI_ADIW_Solve:ADI_CalcOutput_IW:InflowWind_CalcOutput:CalculateOutput:IfW_FlowField_GetVelAcc:Grid3DField_GetCell: G3D wind array boundaries violated. Grid too small in Z direction (Z=165.07 m is above grid.)”
The inflow is set as a FF turbulence wind and the same file for OLAF model as that for BEM model. The highest grid in inflow is set as 85+160/2=165m according to my set-up. Thus, the 165.07m is indeed outside my wind field, but my question is why this happen? In BEM model, this wind inflow is feasible.
My wake pannels and regularization parameters are set accoring to the recommendations in online documentation of OpenFAST.
Dear @TianCheng.Yao,
In BEM, the aerodynamic analysis nodes where inflow wind data is needed all lie on the rotor and tower. In OLAF, there are also aerodynamic analysis nodes in the wake where inflow wind data is needed, so, the grids may need to be larger when running OLAF versus BEM.
Best regards,
Dear @Jason.Jonkman ,
Thanks for your reply! But the GridHeight in the current .inp file (160m) is close to the maximum restricted by the HubHt (85m), where GridHeight must be set smaller than twice of HubHt to make al points of the grid above ground level. Besides, the rotor radius is 65m in my research, which is much smaller than the half of the current GridHeight.
I will increase the GridHeight to a value close to the thresold like 168m and try it again.
Btw, I want to confirm if I can keep the RefHt as the real hub height as 85m and increase the parameter HubHt to a lager value like 100m so that GridHeight can be increased to like 190m to generate the wind field I required?
Best regards,
Dear @TianCheng.Yao,
I would first try keeping HubHt physically correct and increasing GridHeight to its maximum possible value (limited by HubHt).
If that is not large enough, you could set HubHt higher than is physically correct; we often do this when using TurbSim to generate inflow for use in FAST.Farm. But this approach is subject to the limitations discussed in the following OpenFAST issue that has not been resolved yet: Decouple Hub Height from Grid in TurbSim · Issue #199 · OpenFAST/openfast · GitHub.
Best regards,