Thank you @luc. Let me show some of related code. It is the Python wrapper and .ipynb notebook. After preparation I execute cells 1 through 3 one by one:
#cell 1
def calc_oceanTides_acceleration(inertial_frame, time_moment, state_inertial, timestep, points, degree):
ut1 = TimeScalesFactory.getUT1(IERSConventions.IERS_2010, True)
earth_frame = FramesFactory.getITRF(IERSConventions.IERS_2010, False)
gravityProvider = GravityFieldFactory.getNormalizedProvider(100, 100)
oceanTides = OceanTides(earth_frame, gravityProvider.getAe(), gravityProvider.getMu(),
True, timestep, points, degree, degree, IERSConventions.IERS_2010, ut1)
state = SpacecraftState(AbsolutePVCoordinates(inertial_frame, time_moment, state_inertial))
return oceanTides.acceleration(state, ForceModel.cast_(oceanTides).getParameters()).toArray()
#cell 2
acc10 = calc_oceanTides_acceleration(FramesFactory.getGCRF(), time_moments[0], state_inertial_true[0], 600.0, 12, 10)
print(acc10)
output: [-1.579685889400383e-08, -3.247904310426961e-09, 3.1001379770842736e-08]
#cell 3 (executed right after cell 2):
acc20 = calc_oceanTides_acceleration(FramesFactory.getGCRF(), time_moments[0], state_inertial_true[0], 600.0, 12, 20)
print(acc20)
output: [-1.579685889400383e-08, -3.247904310426961e-09, 3.1001379770842736e-08]
Note that outputs are identical besides the degree and order changed from 10 to 20.
Then I restart the kernel, prepare, execute cell 1 and then cell 3, skipping cell 2:
#cell 3
acc20 = calc_oceanTides_acceleration(FramesFactory.getGCRF(), time_moments[0], state_inertial_true[0], 600.0, 12, 20)
print(acc20)
output: [-7.122729011616203e-09, 5.8980470410523975e-09, 4.178373788888947e-08]
A noticable effect in acceleration can be observed, as expected. So it looks like the forcemodel loads 10 harmonics from the tide model file and then reuses them despite for the second time the function asks to rebuild everything with 20 harmonics. Looks like I have to reload the forcemodel or tidemodel provider explicitly somehow?