I am working with modelling of FOWT in FAST v.8. In ElastoDyn input, the mode shape of each tower modes is necessary to be inputted. I used BModes to derive those mode shapes. However, before I use it to model 2MW FOWT I checked the values of mode shapes used in ElastoDyn of OC3 Hywind project (coefficients of six order polynomial fitted values) and I compare with the one I obtained from BModes (obtained from OC3 Hywind’s Bmodes model) and fitted by using polynomial equation. I found that the values of 1st tower fore-aft and side-side obtained from BModes give good agreement with FAST default values in OC3 Hywind FAST demo file, but the values of mode shapes of 2nd fore-aft and side-side obtained by BModes are differnt from FAST ElastoDyn input default values. So, I am wondering if BModes can be used to derive mode shapes for FAST? Could you please give me some suggestion on this?
Thank you in advance
This question has been asked and answered on this forum before–e.g. see the posts dated May 07-08, 2018 in the following forum topic: http://forums.nrel.gov/t/ansys-model-tower/1722/12.