OC4 P2 LC2.2 Irregular waves |
 
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OC4 P2 LC2.2 Irregular waves |
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Results for irregular wave cases are presented in terms of mean and variance of key parameters rather than full time histories. To facilitate comparisons, Robertson et al. (2014) focus on the key outputs of platform surge, platform pitch and bending moment at the base of the tower. Generally speaking, Flexcom shows good agreement with the other software tools. Note that results from Bladed (GH) were not found in the IEA Wind Task 30 results library, so we have used results from Bladed Advanced Hydro Beta (GH) instead in this comparison.
The mean surge response shows considerable variation across the different software products. As noted by Robertson et al. (2014), it seems likely that the discrepancy is caused by different approaches to modelling drift forces (as mentioned in OC4 P2 LC2.1).
Flexcom's mean pitch response shows good agreement with the other software tools, particularly considering the variation across the different products. It is worth noting that the mean pitch is very small (<.0.1 degrees for most participants), so any discrepancies are extremely minor.
Flexcom's mean tower base moment shows good agreement with the other software tools.
The variance in surge shows some variation across the different software products, again possibly caused by different approaches to modelling drift forces. Results from Charm3D+FAST (ABS) show a surge variance which is larger than the other software tools.
The variance in pitch shows reasonable agreement across the different software products, with the exception of HAWC2 (DTU) where the pitch variance appears larger than the others. Again it is worth noting that the pitch variance is quite small (<.0.25 degrees for most participants), so any discrepancies are extremely minor.
The variance in tower base moment shows reasonable agreement across the different software products, with the exception of HAWC2 (DTU) which appears to be inconsistent with the others. Robertson et al. (2014) suggest that this probably results from an incorrectly prescribed axis definition for the output.
