Update zero_cross and add nansasena

data/processing/nandasena.py

@@ -0,0 +1,27 @@
+import numpy as np
+
+def u_nandasena(b, c, C_d, C_l, rho_s, rho_w=1e3, theta=0, g=9.81, **_):
+    return np.sqrt(
+        (2 * (rho_s/rho_w - 1) * g * c * np.cos(np.radians(theta)))
+        / C_l
+    )
+
+
+const = {
+    "a": 4,
+    "b": 2.5,
+    "c": 2,
+    "C_d": 1.95,
+    "C_l": 0.178,
+    "theta": 0,
+    "rho_s": 2.7e3,
+}
+
+u = u_nandasena(**const)
+u_ola = 14.5
+print(f"Nandasena: u={u:5.2f}m/s")
+print(f"Olaflow:   u={u_ola:5.2f}m/s")
+print(f"Gap:      du={abs(u_ola - u):5.2f}m/s")
+print(f"Gap:      du={abs(u_ola - u)/u:5.2%}")
+print(f"Gap:      du={abs(u_ola - u)/u_ola:5.2%}")
+