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Laws of Resistance in Transitional Pipe Flows
Rory T Cerbus1, Chien-Chia Liu1, Gustavo Gioia1
1Okinawa Institute of Science and Technology Graduate University, Onna-son, Okinawa 904-0495, Japan.
Physical Review Letters
|February 27, 2018
Summary
Transitional pipe flow, previously poorly understood, is clarified by distinguishing laminar plugs and turbulent flashes. This research reveals laminar plugs follow the laminar flow law, while flashes adhere to the turbulent flow law.
Area of Science:
- Fluid Dynamics
- Physics of Flow Regimes
Background:
- Pipe flow transitions from laminar to turbulent at higher velocities.
- The intermediate transitional regime, characterized by alternating laminar plugs and turbulent flashes, remains poorly understood.
- Osborne Reynolds' laws of resistance successfully described laminar and turbulent flows but not transitional flow.
Purpose of the Study:
- To elucidate the poorly understood transitional flow regime in pipes.
- To differentiate the resistance laws governing laminar plugs and turbulent flashes.
- To provide a quantitative understanding of fluid friction in transitional pipe flow.
Main Methods:
- Experimental investigation of pipe flow dynamics.
- Numerical simulations to model transitional flow behavior.
- Distinguishing between laminar plugs and turbulent flashes within the transitional regime.
Main Results:
- The law of resistance for laminar plugs in the transitional regime was identified as corresponding to the established laminar flow law.
- The law of resistance for turbulent flashes in the transitional regime was found to be identical to the turbulent flow law.
- A clear distinction in resistance laws was demonstrated for the two distinct flow types within the transitional regime.
Conclusions:
- The transitional flow regime can be understood by analyzing its distinct components: laminar plugs and turbulent flashes.
- The previously unknown laws of resistance for transitional flow have been determined.
- This study resolves a long-standing gap in understanding fluid dynamics and the laws of resistance.
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