vamseeachanta DOF Percentage Calculation (+2)
DOF Percentage Calculation
For each mode, the DOF percentage indicates how much of the mode's energy is in each degree of freedom:
DOF_percentage = (|max_DOF_value|² / Σ|all_DOF_values|²) × 100
Mode Selection Criteria
A mode is "selected" for a DOF when:
DOF_percentage > threshold_percentage
This filtering helps identify:
- Heave-dominated modes (Z threshold)
- Surge/sway modes (X/Y threshold)
- Roll/pitch/yaw modes (Rotation thresholds)
Relationship to VIV
Modal frequencies are critical for VIV assessment:
# VIV lock-in check
from digitalmodel.subsea.viv_analysis.viv_analysis import VIVAnalysis
viv = VIVAnalysis()
# Get natural frequency from modal analysis
natural_freq = 1 / mode_period # Hz
*See sub-skills for full details.*