ENGINEERING – PIPE FLOW & WATER UPPLY CALCULATOR
Swamee Jain
A precise tool.
What is the Swamee Jain & How does it work?
In pipe flow the balance between inertial forces and viscous forces is expressed by the Reynolds number (Re = frac{rho V D}{mu}). Low values (<2000) indicate laminar flow, high values (>4000) indicate turbulent flow, where the friction factor becomes a function of both roughness and Reynolds number.
The absolute roughness (varepsilon) characterises the microscopic protrusions on the pipe wall. In turbulent flow the roughness interacts with the turbulent eddies, increasing energy loss. The SwameeβJain correlation provides an explicit approximation for the DarcyβWeisbach friction factor without iterative solution.
The SwameeβJain formula is given by:
\[ f = \frac{0.25}{\left[ \log_{10}\!\left( \frac{\varepsilon}{3.7D} + \frac{5.74}{Re^{0.9}} \right) \right]^2 }\]
f = DarcyβWeisbach friction factor (dimensionless)
Parameters
Result
β
Frequently Asked Questions
What is the Reynolds number in fluid dynamics?
The Reynolds number is a dimensionless quantity that helps predict flow patterns in different fluid flow situations, especially concerning whether the flow is laminar or turbulent.
How does Swamee-Jain correlation help in pipe flow calculations?
Swamee-Jain correlation provides an empirical formula to estimate the Darcy friction factor for fully developed turbulent flow in pipes, considering both Reynolds number and relative roughness.
What is the significance of absolute roughness (Ξ΅) in pipe flow?
Absolute roughness (Ξ΅) represents the microscopic irregularities on the pipe's inner surface that affect fluid flow, particularly in turbulent conditions where it increases energy loss.
When is the Reynolds number considered low for turbulent flow?
A Reynolds number below 4000 typically indicates turbulent flow, where viscous forces dominate over inertial forces.
How does roughness affect friction factor in turbulent flow?
In turbulent flow, the roughness of the pipe wall interacts with eddies, increasing the energy loss and thus affecting the friction factor significantly more than in smooth pipes.
Can Swamee-Jain correlation be used for all types of fluids?
Swamee-Jain correlation is generally applicable to Newtonian fluids under turbulent flow conditions. It may not be suitable for non-Newtonian fluids or laminar flows.
What are the limitations of using Swamee-Jain correlation?
The correlation is most accurate for fully developed turbulent flow and pipes with a relative roughness between 0.001 and 0.04. It may not be reliable for very high Reynolds numbers or extremely smooth surfaces.
Results are for informational purposes only and do not constitute professional advice.