Modifying 'cos' to get the angle beween v fluctuations and the magnetic field

postprocessor.py

@@ -8,14 +8,6 @@ vol_func = lambda dset: dset["dx"] ** 3  # Volume function
 getter_T = lambda dset: dset["P"] / dset["rho"]  # Temperature
 
 
-def getter_abs_cos_vB(dset):
-    B_norm = np.sqrt(np.sum(dset["Br"] ** 2, axis=1))
-    v_norm = np.sqrt(np.sum(dset["vel"] ** 2, axis=1))
-    # Compute the dot product in each cell
-    dot_prod = np.einsum("ij,ij->i", dset["vel"], dset["Br"])
-    return np.abs(dot_prod) / (v_norm * B_norm)
-
-
 def getter_B_int(dset):
     B_norm = np.sqrt(np.sum(dset["Br"] ** 2, axis=1))
     return B_norm
@@ -341,6 +333,20 @@ class PostProcessor(HDF5Container):
             self.unload_cells()
         return ({"rho": centers, "B": B_mean}, {"logbins": logbins})
 
+    def cos_vfluct_B(self):
+
+        mean_speed = self.save.get_node("/globals/mwa_speed").read()
+
+        def getter_cos_vfluct_B(dset):
+            vel_fluct = dset["vel"] - mean_speed
+            B_norm = np.sqrt(np.sum(dset["Br"] ** 2, axis=1))
+            v_norm = np.sqrt(np.sum(vel_fluct ** 2, axis=1))
+            # Compute the dot product in each cell
+            dot_prod = np.einsum("ij,ij->i", vel_fluct, dset["Br"])
+            return np.abs(dot_prod) / (v_norm * B_norm)
+
+        return self._vol_pdf(getter_cos_vfluct_B)
+
     def _mwa_sigma(self, axes=["x", "y", "z"]):
         mw_speed = self.save.get_node("/globals/mwa_speed").read()
 
@@ -817,9 +823,10 @@ class PostProcessor(HDF5Container):
             ),
             "cos_pdf": Rule(
                 self,
-                partial(self._vol_pdf, getter_abs_cos_vB, logbins=False),
-                "Global cos-PDF",
+                partial(self.cos_vfluct_B),
+                "Global cos fluctuation-PDF",
                 "/hist",
+                dependencies=["mwa_speed"],
                 unit=cst.none,
             ),
             "Brho": Rule(