def test_Froude_Krylov():
from capytaine.bem.airy_waves import froude_krylov_force
from capytaine.bodies.predefined.spheres import Sphere
from capytaine.bem.problems_and_results import DiffractionProblem
sphere = Sphere(radius=1.0, ntheta=3, nphi=12, clever=True, clip_free_surface=True)
sphere.add_translation_dof(direction=(0, 0, 1), name="Heave")
problem = DiffractionProblem(body=sphere, omega=1.0, sea_bottom=-np.infty)
assert np.isclose(froude_krylov_force(problem)['Heave'], 27596, rtol=1e-3)
problem = DiffractionProblem(body=sphere, omega=2.0, sea_bottom=-np.infty)
assert np.isclose(froude_krylov_force(problem)['Heave'], 22491, rtol=1e-3)
problem = DiffractionProblem(body=sphere, omega=1.0, sea_bottom=-10.0)
assert np.isclose(froude_krylov_force(problem)['Heave'], 27610, rtol=1e-3)
def records(self):
params = self.problem._asdict()
FK = froude_krylov_force(self.problem)
return [dict(**params,
influenced_dof=dof,
diffraction_force=self.forces[dof],
Froude_Krylov_force=FK[dof])
for dof in self.influenced_dofs]
def records(self):
from capytaine.bem.airy_waves import froude_krylov_force
FK = froude_krylov_force(self.problem)
return [
dict(self.settings_dict,
influenced_dof=dof,
diffraction_force=self.forces[dof],
Froude_Krylov_force=FK[dof]) for dof in self.influenced_dofs
]
sea_bottom=-depth,
omega=omega,
radiating_dof='Heave')
diff_solution = solver.solve(diff_problem)
rad_solution = solver.solve(rad_problem)
# Read mesh properties
faces_centers = body.mesh.faces_centers
faces_normals = body.mesh.faces_normals
faces_areas = body.mesh.faces_areas
from capytaine.bem.airy_waves import airy_waves_potential, airy_waves_velocity, froude_krylov_force
# Computation from the diffraction solution (Capytaine)
FK = froude_krylov_force(diff_problem)['Heave']
diff_force = diff_solution.forces['Heave']
# Get potentials
phi_inc = airy_waves_potential(faces_centers, diff_problem)
v_inc = airy_waves_velocity(faces_centers, diff_problem)
phi_rad = rad_solution.potential
# Indirect computation from the radiation solution, via the Haskind relation
integrand = -(phi_inc * faces_normals[:, 2] -
phi_rad * np.diag(v_inc @ faces_normals.T))
F_hask = 1j * omega * rho * np.sum(integrand * faces_areas)
# Direct integration of the potentials
diff_force_recomputed = -1j * omega * rho * np.sum(
diff_solution.potential * faces_areas * faces_normals[:, 2])
