added the algorithm to compute Reynolds number

physics/reynolds_number

@@ -0,0 +1,57 @@
+"""
+Title : computing the Reynolds number to find
+        out the type of flow (laminar or turbulent)
+
+Reynolds number is a dimensionless quantity that is used to determine
+the type of flow pattern as laminar or turbulent while flowing through a
+pipe. Reynolds number is defined by the ratio of inertial forces to that of
+viscous forces.
+
+R = Inertial Forces / Viscous Forces
+R = (ρ * V * D)/μ
+
+where :
+ρ = Density of fluid (in Kg/m^3)
+D = Diameter of pipe through which fluid flows (in m)
+V = Velocity of flow of the fluid (in m/s)
+μ = Viscosity of the fluid (in Ns/m^2)
+
+If the Reynolds number calculated is high (greater than 2000), then the
+flow through the pipe is said to be turbulent. If Reynolds number is low
+(less than 2000), the flow is said to be laminar. Numerically, these are
+acceptable values, although in general the laminar and turbulent flows
+are classified according to a range. Laminar flow falls below Reynolds
+number of 1100 and turbulent falls in a range greater than 2200.
+Laminar flow is the type of flow in which the fluid travels smoothly in
+regular paths. Conversely, turbulent flow isn't smooth and follows an
+irregular math with lots of mixing.
+
+Reference : https://byjus.com/physics/reynolds-number/
+"""
+
+def reynolds_number(density:float, velocity:float, diameter:float, viscosity:float) -> float :
+    """
+    >>> reynolds_number(900,2.5,0.05,0.4)
+    281.25
+    >>> reynolds_number(450,3.86,0.078,0.23)
+    589.0695652173912
+    >>> reynolds_number(234,-4.5,0.3,0.44)
+    717.9545454545454
+    >>> reynolds_number(-90,2,0.045,1)
+    Traceback (most recent call last):
+        ...
+    ValueError: please ensure that density, diameter and viscosity are non negative
+    >>> reynolds_number(0,2,-0.4,-2)
+    Traceback (most recent call last):
+        ...
+    ValueError: please ensure that density, diameter and viscosity are non negative
+    """
+
+    if density <= 0 or diameter <=0 or viscosity <= 0 :
+        raise ValueError("please ensure that density, diameter and viscosity are non negative")
+    return (density * abs(velocity) * diameter)/viscosity
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()