# @author Christian Diddens # @author Duarte Rocha # # @section LICENSE # # pyoomph - a multi-physics finite element framework based on oomph-lib and GiNaC # Copyright (C) 2021-2025 Christian Diddens & Duarte Rocha # # This program is free software: you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . # # The authors may be contacted at c.diddens@utwente.nl and d.rocha@utwente.nl # # ======================================================================== from pyoomph import * from pyoomph.equations.poisson import * # use the pre-defined Poisson equation from pyoomph.expressions.units import * class FishMesh(MeshTemplate): def __init__(self, size=1, mouth_angle=45*degree, fin_angle=50*degree,mouth_depth_factor=0.5,fin_length_factor=0.45,fin_height_factor=0.8,domain_name="fish"): super(FishMesh, self).__init__() self.size = size # overall size of the fish (potentially dimesional) self.mouth_angle=mouth_angle # angle of the mouth-opening (with respect to the body center) self.mouth_depth_factor=mouth_depth_factor # depth of the mouth self.fin_angle=fin_angle # angle of the fin-body-connection (with respect to the body center) self.fin_length_factor=fin_length_factor self.fin_height_factor = fin_height_factor self.domain_name = domain_name # name of the fish domain def define_geometry(self): domain = self.new_domain(self.domain_name) S=self.nondim_size(self.size) # Important: Nondimensionalize the potentially dimensional size # Corner nodes of the fish n_mouth_center=self.add_node_unique(-(1-self.mouth_depth_factor)*S,0) n_upper_jaw = self.add_node_unique(-cos(self.mouth_angle / 2) * S, sin(self.mouth_angle / 2)*S) n_lower_jaw=self.add_node_unique(-cos(self.mouth_angle/2)*S,-sin(self.mouth_angle/2)*S) n_upper_body_fin=self.add_node_unique(cos(self.fin_angle/2)*S,sin(self.fin_angle/2)*S) n_lower_body_fin = self.add_node_unique(cos(self.fin_angle / 2) * S, -sin(self.fin_angle / 2) * S) n_center_body_fin = self.add_node_unique(cos(self.fin_angle / 2) * S, 0) n_upper_fin_corner=self.add_node_unique((cos(self.fin_angle / 2)+self.fin_length_factor) * S, self.fin_height_factor * S) n_lower_fin_corner = self.add_node_unique((cos(self.fin_angle / 2) + self.fin_length_factor) * S,-self.fin_height_factor * S) n_center_fin_end = self.add_node_unique((cos(self.fin_angle / 2) + self.fin_length_factor) * S, 0) # Elements domain.add_quad_2d_C1(n_lower_jaw,n_lower_body_fin,n_mouth_center,n_center_body_fin) # lower body part domain.add_quad_2d_C1(n_mouth_center, n_center_body_fin,n_upper_jaw, n_upper_body_fin ) # upper body part domain.add_quad_2d_C1(n_lower_body_fin,n_lower_fin_corner,n_center_body_fin,n_center_fin_end) # lower fin part domain.add_quad_2d_C1(n_center_body_fin,n_center_fin_end,n_upper_body_fin,n_upper_fin_corner) # upper fin part # Curved entities upper_body_curve=self.create_curved_entity("circle_arc",n_upper_jaw,n_upper_body_fin,center=[0,0]) lower_body_curve = self.create_curved_entity("circle_arc", n_lower_jaw, n_lower_body_fin, center=[0, 0]) self.add_facet_to_curve_entity([n_upper_jaw,n_upper_body_fin],upper_body_curve) # top body curve self.add_facet_to_curve_entity([n_lower_body_fin, n_lower_jaw], lower_body_curve) # bottom body curve # Add nodes to boundaries self.add_nodes_to_boundary("curved",[n_upper_body_fin, n_lower_body_fin,n_lower_jaw,n_upper_jaw]) # nodes on curved body parts self.add_nodes_to_boundary("mouth", [ n_lower_jaw,n_upper_jaw,n_mouth_center]) # nodes of the mouth self.add_nodes_to_boundary("fin",[n_upper_body_fin,n_lower_body_fin,n_center_fin_end,n_upper_fin_corner,n_lower_fin_corner]) # fin class MeshTestProblem(Problem): def __init__(self): super(MeshTestProblem, self).__init__() self.fish_size=1*meter # quite large fish, isn't it...? self.max_refinement_level = 5 # maximum level of refinements self.space="C2" def define_problem(self): self.add_mesh(FishMesh(size=self.fish_size)) self.set_scaling(spatial=self.fish_size) # Nondimensionalize space by the fish size eqs = MeshFileOutput() # We must set a meter^2 coefficient to be consistent with the units eqs += PoissonEquation(name="u", source=1, space=self.space,coefficient=1*meter**2) # Boundaries all u=0 eqs += DirichletBC(u=0)@"fin" eqs += DirichletBC(u=0) @ "mouth" eqs += DirichletBC(u=0) @ "curved" # refine the curved boundary to the highest order (i.e. max_refinement_level) during adaptive solves eqs += RefineToLevel("max")@"curved" eqs += SpatialErrorEstimator(u=1) # and adapt on all other elements based on the error self.add_equations(eqs @ "fish") if __name__ == "__main__": with MeshTestProblem() as problem: problem.solve(spatial_adapt=problem.max_refinement_level) problem.output_at_increased_time()