BBH ID: set Gaussian falloff widths

sxs-collaboration · Apr 12, 2024 · b683530 · b683530
1 parent c2fa145
commit b683530
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Showing 3 changed files with 18 additions and 1 deletion.
diff --git a/support/Pipelines/Bbh/InitialData.py b/support/Pipelines/Bbh/InitialData.py
@@ -16,6 +16,11 @@
 ID_INPUT_FILE_TEMPLATE = Path(__file__).parent / "InitialData.yaml"
 
 
+def L1_distance(m1, m2, separation):
+    """Distance of the L1 Lagrangian point from m1, in Newtonian gravity"""
+    return separation * (0.5 - 0.227 * np.log10(m2 / m1))
+
+
 def id_parameters(
     mass_ratio: float,
     dimensionless_spin_a: Sequence[float],
@@ -49,6 +54,7 @@ def id_parameters(
     M_B = 1.0 / (1.0 + mass_ratio)
     x_A = separation / (1.0 + mass_ratio)
     x_B = x_A - separation
+    # Spins
     chi_A = np.asarray(dimensionless_spin_a)
     r_plus_A = M_A * (1.0 + np.sqrt(1 - np.dot(chi_A, chi_A)))
     Omega_A = -0.5 * chi_A / r_plus_A
@@ -57,6 +63,11 @@ def id_parameters(
     r_plus_B = M_B * (1.0 + np.sqrt(1 - np.dot(chi_B, chi_B)))
     Omega_B = -0.5 * chi_B / r_plus_B
     Omega_B[2] += orbital_angular_velocity
+    # Falloff widths of superposition
+    L1_dist_A = L1_distance(M_A, M_B, separation)
+    L1_dist_B = separation - L1_dist_A
+    falloff_width_A = 3.0 / 5.0 * L1_dist_A
+    falloff_width_B = 3.0 / 5.0 * L1_dist_B
     return {
         "MassRight": M_A,
         "MassLeft": M_B,
@@ -78,6 +89,8 @@ def id_parameters(
         "HorizonRotationLeft_x": Omega_B[0],
         "HorizonRotationLeft_y": Omega_B[1],
         "HorizonRotationLeft_z": Omega_B[2],
+        "FalloffWidthRight": falloff_width_A,
+        "FalloffWidthLeft": falloff_width_B,
         # Resolution
         "L": refinement_level,
         "P": polynomial_order,

diff --git a/support/Pipelines/Bbh/InitialData.yaml b/support/Pipelines/Bbh/InitialData.yaml
@@ -48,7 +48,9 @@ Background: &background
     AngularVelocity: {{ OrbitalAngularVelocity }}
     Expansion: {{ RadialExpansionVelocity }}
     LinearVelocity: [0., 0., 0.]
-    FalloffWidths: [4.8, 4.8]
+    FalloffWidths:
+      - {{ FalloffWidthLeft }}
+      - {{ FalloffWidthRight }}
 
 InitialGuess: *background
 

diff --git a/tests/support/Pipelines/Bbh/Test_InitialData.py b/tests/support/Pipelines/Bbh/Test_InitialData.py
@@ -63,6 +63,8 @@ def test_generate_id(self):
             [params[f"HorizonRotationLeft_{xyz}"] for xyz in "xyz"],
             [-0.337933017966707, -0.422416272458383, -0.49689952695006],
         )
+        self.assertAlmostEqual(params["FalloffWidthRight"], 6.479672589667676)
+        self.assertAlmostEqual(params["FalloffWidthLeft"], 5.520327410332324)
         self.assertEqual(params["L"], 1)
         self.assertEqual(params["P"], 5)
         # COM is zero