boundary_types = p,p
boundary_values = 0,4
initial_gradients =          10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5,   10,  -0.5,   0.5
reflection_path =  (0,-1),(1,0),(2,-1),(1,-1),(2,0),(3,-1),(2,-1),(3,0),(4,-1),(3,-1),(4,0),(5,-1),(4,-1),(5,0),(6,-1),(5,-1),(6,0),(7,-1),(6,-1),(7,0),(8,-1),(7,-1),(8,0),(9,-1),(8,-1),(9,0)
grid_size = 10
max_radius = 90%