[cmccomb]

Summary

Include the orifice piston force in the generalized-body-mode (GBM) state input of OWC/OrificeModel/OWC_GBM.slx. Previously, the force reached the reported flexible-body acceleration while the state-space integration received wave excitation alone. The new sum sends excitation plus piston force to Product4/2; the existing flexible stiffness and damping remain in the state-space block.

Set simu.dt = 0.00015625 s in the published input, with simu.dtOut = 0.005 s. Explicit cicDt, nonlinearDt, and morisonDt values retain their original 0.005 s force-sampling clocks. WEC-Sim initialization overwrites the model's saved MaxStep with simu.dt, so changing the .slx setting alone was insufficient. A full audit at the old 0.005 s step found 1.687 m maximum surge and 1.62% PTO-work differences against a refined solver run, with identical waves and no Mach-limit events. The published-input run is being checked through cmudrc/wec-sim-python#627.

The model was edited and saved in MATLAB R2023b, matching the original model release. The reproducible signal-edit script asserts the original wiring. The model in this PR has SHA-256 5f9f1da3bf73e85b52224a3ff483991c3ec60774b92856e3c45cda4347927b59; its alternate configuration remains at the original settings, and the active one changes only MaxStep.

Validation

• Started from Applications commit d53d4d4c9eda2581f04204f5d394a6ef84bb099e, with WEC-Sim core 0753b2e47f2457c078751dcfe5d251d1767b80ab and pinned cleaned Test 17a hydrodynamics.
• The R2023b-saved signal correction passed a full 130 s hosted source run with MaxStep refined at runtime. Its six output arrays matched the prior R2025b-model CI run exactly, reproduced the archived baseline within 1e-9, and passed independent Python motion and air-system gates in cmudrc/wec-sim-python#627. Maximum Python/source surge difference was 2.246 mm; signed PTO work differed by 0.0717%; peak internal-air Mach was 0.155.
• A direct saved-setting gate exposed WEC-Sim's MaxStep override. The full 130 s published-input run with preserved force clocks passed MATLAB simulation, fresh-source packing, and the independent Python motion, PTO, and air-system gate. Its six exported arrays reproduce the archived refined trace within 3.96e-11; source work is 864.422 J and peak Mach is 0.155. The final source workflow run also passes the strict 1e-9 archive assertion and fresh-source Python gate.

Related to cmudrc/wec-sim-python#622.