[BUG] from_windio_with_monopile produces much lower frequency even without soil stiffness

[TheMercer]

pyBmodes version

1.15.1

Python version

3.11.15

How did you install pyBmodes?

pip install pybmodes (from PyPI)

Operating system

Windows 11

What happened?

Same E, Rho, v in both setups

Frequency came around around 0.11/12 Hz in PyBModes but same model in OrcaFlex (built from same yaml) has frequency to about 0.17 Hz which matches IEA official documentation (with soil).

With soil,
Pybmodes produces 0.12 Hz
OrcaFlex prodcues 0.17 Hz

without soil.
Pybmodes produces 0.14 Hz
OrcaFlex prodcues 0.13 Hz

OrcaFlex model with distrubuted or soil from pybmode 6by6.
Frequency goes from 0.13 Hz to 0.17 Hz (0.17 Hz expected from IEA models)

But pybmodes the frequency drops even more.

No Monopile just tower, TWR frequencys
Pybmodes produces 0.2440 Hz
OrcaFlex prodcues 0.225 Hz

What did you expect?

Frequencies closer alignment

Minimal reproducer

Turbine_yaml = r"IEA-15-240-RWT.yaml"

blade = RotatingBlade.from_windio(Turbine_yaml, n_span = 50)

rna_mass = TipMassProps(
                mass=945e3, 
                cm_offset=-7.1320950209625344,
                cm_axial=-4.579560959672458,
                ixx=348.72381693267205e6, 
                iyy=199.37067513294413e6, 
                izz=199.62365952233595e6, 
                ixy=246.15077980892823e3, 
                izx=-14.735633479540566e6, 
                iyz=-45.14955039893567e3,
            )

tower = Tower.from_windio_with_monopile(Turbine_yaml, tip_mass = rna_mass, n_nodes = 50)

Traceback or unexpected output

Anything else?

No response

[TheMercer]

Actually the tower fixed bottom no monopile mismatch. Question is why then why does the frequency miss match in monopile and with soil

Soil is fine I believe. I took the 6by6 form PyBmodes and it works fine to what the distribution soil would of been so soil it self isn't the issues.

Some fundamental definition in monopile and twr could be wrong?

[TheMercer]

Even without point mass, monopile, just the tower

Pybmodes: 0.7732 Hz
OrcaFlex: 0.79959 Hz