add fluid methods

ntrfc/fluid/fluid.py

@@ -120,3 +120,26 @@ def isentropic_total_temperature(kappa, mach_number, temperature):
     isentropic_total_temperature = temperature / (1 + (kappa - 1) / 2 * mach_number ** 2) ** -1
     return isentropic_total_temperature
 
+
+
+def speed_of_sound(*, gamma, R=None, p=None, rho=None, T=None):
+    """Calculate the speed of sound based on the given equation.
+    https://www.grc.nasa.gov/www/BGH/isentrop.html
+
+    Args:
+        gamma (float): The specific heat ratio.
+        p (float): The pressure of the gas.
+        rho (float): The density of the gas.
+        R (float): The specific gas constant.
+        T (float): The temperature of the gas.
+
+    Returns:
+        float: The speed of sound.
+    """
+    if not T and not R:
+        a = np.sqrt(gamma * p / rho)
+    elif not rho:
+        a = np.sqrt(gamma * R * T)
+    return a
+
+

tests/fluid/test_ntrfc_fluid.py

 import numpy as np
 
 from ntrfc.fluid.fluid import total_pressure, mach_number, sutherland_viscosity, ma_is, isentropic_reynolds_number, \
-    isentropic_total_temperature
+    isentropic_total_temperature, speed_of_sound
 
 
 def test_total_pressure():
@@ -50,3 +50,12 @@ def test_isentropic_total_temperature():
     expected_output = 315
     output = isentropic_total_temperature(1.4, 0.5, 300)
     assert abs(output - expected_output) < 1e-2
+
+
+def test_speed_of_sound():
+        assert abs(speed_of_sound(gamma=1.4, p=101325, rho=1.225) - 340.29) < 0.01
+        assert abs(speed_of_sound(gamma=1.3, p=101325, rho=1.225) - 327.92) < 0.01
+        assert abs(speed_of_sound(gamma=1.4, p=80000, rho=1.225) - 302.37) < 0.01
+        assert abs(speed_of_sound(gamma=1.3, p=80000, rho=1.225) - 291.37) < 0.01
+        assert abs(speed_of_sound(gamma=1.4, R=287.05, T=288.15) - 340.29) < 0.01
+        assert abs(speed_of_sound(gamma=1.3, R=287.05, T=288.15) - 327.91) < 0.01