From f3acb52cadade9e7d012bf7f50cad32669b67b75 Mon Sep 17 00:00:00 2001
From: Paarth Goyal <138299656+pluto-tofu@users.noreply.github.com>
Date: Tue, 10 Oct 2023 10:54:04 +0530
Subject: [PATCH] Added the algorithm to compute Reynolds number in the physics
 section (#9913)

* added the algorithm to compute Reynolds number

* fixed file name issue

* Apply suggestions from code review

---------

Co-authored-by: Tianyi Zheng <tianyizheng02@gmail.com>
---
 physics/reynolds_number.py | 63 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 63 insertions(+)
 create mode 100644 physics/reynolds_number.py

diff --git a/physics/reynolds_number.py b/physics/reynolds_number.py
new file mode 100644
index 000000000..dffe690f8
--- /dev/null
+++ b/physics/reynolds_number.py
@@ -0,0 +1,63 @@
+"""
+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 path 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 positive
+    >>> reynolds_number(0, 2, -0.4, -2)
+    Traceback (most recent call last):
+        ...
+    ValueError: please ensure that density, diameter and viscosity are positive
+    """
+
+    if density <= 0 or diameter <= 0 or viscosity <= 0:
+        raise ValueError(
+            "please ensure that density, diameter and viscosity are positive"
+        )
+    return (density * abs(velocity) * diameter) / viscosity
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()