Elastic_trampoline_files #59
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bhosale2
requested changes
Sep 9, 2022
Comment on lines
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| def collision_force(k, phi_1, phi_2, blend_w, grid_size_z, grid_size_r, eps, dx): | ||
| """ | ||
| computes the collision force between 2 bodies | ||
| using their level sets | ||
| """ | ||
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||
| gradient = ( | ||
| spp.diags( | ||
| [-0.5, 0.5, -0.5, 0.5], | ||
| [-1, 1, grid_size_r - 1, -grid_size_r + 1], | ||
| shape=(grid_size_r, grid_size_r), | ||
| format="csr", | ||
| ) | ||
| / dx | ||
| ) | ||
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| gradient_T = ( | ||
| spp.diags( | ||
| [-0.5, 0.5, -0.5, 0.5], | ||
| [-1, 1, grid_size_z - 1, -grid_size_z + 1], | ||
| shape=(grid_size_z, grid_size_z), | ||
| format="csr", | ||
| ) | ||
| / dx | ||
| ) | ||
|
|
||
| phi_diff = 0.5 * (phi_2 - phi_1) | ||
| delta_phi = phi_diff * 0 | ||
| delta_phi += ( | ||
| (np.fabs(phi_diff) < blend_w) | ||
| * 0.5 | ||
| * (1 + np.cos(np.pi * phi_diff / blend_w)) | ||
| / blend_w | ||
| ) | ||
| phi_diff_x = np.mat(phi_diff) * gradient_T | ||
| phi_diff_y = gradient * np.mat(phi_diff) | ||
| s = np.sqrt(np.square(phi_diff_x) + np.square(phi_diff_y)) | ||
| phi_diff_x /= s + eps | ||
| phi_diff_y /= s + eps | ||
| S = phi_diff / np.sqrt(phi_diff**2 + eps**2) | ||
| body_mask = np.logical_or((phi_1 > 0), (phi_2 > 0)) | ||
| force_x = body_mask * S * phi_diff_x * k * delta_phi | ||
| force_y = body_mask * S * phi_diff_y * k * delta_phi | ||
| return force_x, force_y |
Owner
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please write the vectorized versions (slice-based, similar to functions in kernels), Let's skip using the sparse matrices if possible. Also, collision forces should be a part of the main package.
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| def curl(ax, ay, grid_size_z, grid_size_r, dx): | ||
| """ | ||
| compute curl of the vector using CD | ||
| """ | ||
|
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||
| gradient = ( | ||
| spp.diags( | ||
| [-0.5, 0.5, -0.5, 0.5], | ||
| [-1, 1, grid_size_r - 1, -grid_size_r + 1], | ||
| shape=(grid_size_r, grid_size_r), | ||
| format="csr", | ||
| ) | ||
| / dx | ||
| ) | ||
|
|
||
| gradient_T = ( | ||
| spp.diags( | ||
| [-0.5, 0.5, -0.5, 0.5], | ||
| [-1, 1, grid_size_z - 1, -grid_size_z + 1], | ||
| shape=(grid_size_z, grid_size_z), | ||
| format="csr", | ||
| ) | ||
| / dx | ||
| ) | ||
|
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||
| vort = np.mat(ay) * gradient_T - gradient * np.mat(ax) |
Owner
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can't we use compute_vorticity_from_velocity for this? maybe a good idea is to rename that function as compute_vorticity_from_velocity_forcing?
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| def trampoline_level_set( | ||
| inp_X, | ||
| inp_Y, | ||
| center_basal_x, | ||
| distance_between_centers_x, | ||
| center_y, | ||
| r_basal, | ||
| r_tip, | ||
| ): | ||
| """Gives the level set of a Trampoline""" | ||
| # 1. Basal circle | ||
| # 2. Straight line above and below symmetry plane | ||
| # 3. Tip circle | ||
| # center_y = 0.5 | ||
| # r_basal = 0.1 | ||
| # r_tip = 0.05 | ||
| # distance_between_centers_x = 0.3 | ||
| # center_basal_x = 0.2 | ||
| center_tip_x = center_basal_x + distance_between_centers_x | ||
| phi = 0.0 * inp_X | ||
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| basal_theta = np.arccos((r_basal - r_tip) / distance_between_centers_x) | ||
| THETA = np.arctan2((inp_Y - center_y), (inp_X - center_basal_x)) | ||
| idx_one = np.abs(THETA) > basal_theta | ||
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| # In this region, the level set should be circle distance desu | ||
| phi[idx_one] = ( | ||
| np.sqrt( | ||
| (inp_X[idx_one] - center_basal_x) ** 2 + (inp_Y[idx_one] - center_y) ** 2 | ||
| ) |
Owner
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please rename the variables here referring to Z and R, and not X and Y, for better clarity.
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| fx, fy = collision_force( | ||
| 1 * G, ball_phi2, ball_phi1, 2 * moll_zone, grid_size_z, grid_size_r, eps, dx | ||
| ) |
Owner
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x and y? shouldnt it be z and r?
| fx, fy = collision_force( | ||
| 1 * G, ball_phi2, ball_phi1, 2 * moll_zone, grid_size_z, grid_size_r, eps, dx | ||
| ) | ||
| vorticity[...] += dt * curl(fx, 0 * fy, grid_size_z, grid_size_r, dx) |
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| F_total = 2 * np.pi * dx * dx * F_pen + F_un - np.sum(R * ball_char_func2 * fx) | ||
| U_z_cm_part_old = U_z_cm_part | ||
| U_z_cm_part += dt * ((g / rho_s + F_total / part_mass)) | ||
| diff = dt * (g / rho_s + F_total / part_mass) | ||
| part_Z_cm_new = part_Z_cm | ||
| Z_cm = part_Z_cm | ||
| part_Z_cm += U_z_cm_part_old * dt + ( | ||
| 0.5 * dt * dt * (g / rho_s + F_total / part_mass) | ||
| ) | ||
| part_Z_cm_old = part_Z_cm_new |
Owner
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these things should be refactored later in a cleaner fashion, for now, let's keep it, but maybe put a TODO note here saying need to be refactored in a cleaner way.
| diff = 0 | ||
| bad_phi = 0 * Z | ||
| phi_orig = 0 * Z | ||
| total_flux_double = 0 * R_double |
Owner
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remove variables like this that are not being used. For higher grid resolutions this redundant mem allocation can actually build up quickly and slow down things.
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Resolves #51
trampoline.mp4