Investigation of unsteady turbulent flow in the hydrodynamic entrance region of a circular cylindrical pipe

Arestak Sarukhanyan; Garnik Vermishyan; Hovhannes Kelejyan; Arestak Sarukhanyan; Garnik Vermishyan; Hovhannes Kelejyan

doi:10.3934/era.2026030

Electronic Research Archive

2026, Volume 34, Issue 1: 657-675. doi: 10.3934/era.2026030

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Investigation of unsteady turbulent flow in the hydrodynamic entrance region of a circular cylindrical pipe

Department of Water Systems, Hydraulic Engineering and Hydropower, National University of Architecture and Construction of Armenia, 105 Teryan str., Yerevan, Armenia

Received: 12 September 2025 Revised: 16 December 2025 Accepted: 25 December 2025 Published: 20 January 2026

Regularities of viscous fluid flow in the hydrodynamic entrance region of a round pipe under turbulent unsteady flow conditions were studied, taking into account the tangential stresses that develop between the fluid layers. What distinguishes the proposed research is the method for generating tangential tensions between fluid layers, which impacts the accurate monitoring of the current hydrodynamic events. The study was based on the system of differential equations of viscous fluid flow, where viscous forces in turbulent flows were calculated using the Prandtl calculation method for stationary turbulent flows. Nevertheless, this formula could also be used in the case of unstable turbulent flows. This theory about the appearance of viscous forces in turbulent flows led to the creation of a mathematical model of the issue and the development of a method for its integration. Integration throughout the length of the inlet transition section led to the derivation of calculation formulas for the hydrodynamic properties of the current. These calculations showed the ongoing phenomena. In order to accurately design the transition sections of automatic hydrocontrolled equipment, it was crucial to understand the inlet transition section. Conclusions were drawn from the analysis of the results of computerized experimental research using the obtained analytical solutions. Scientific research and engineering applications may benefit from the study's findings.
- hydrodynamic entrance region,
- turbulent regime,
- velocity,
- unsteady flow
Citation: Arestak Sarukhanyan, Garnik Vermishyan, Hovhannes Kelejyan. Investigation of unsteady turbulent flow in the hydrodynamic entrance region of a circular cylindrical pipe[J]. Electronic Research Archive, 2026, 34(1): 657-675. doi: 10.3934/era.2026030

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Abstract

Regularities of viscous fluid flow in the hydrodynamic entrance region of a round pipe under turbulent unsteady flow conditions were studied, taking into account the tangential stresses that develop between the fluid layers. What distinguishes the proposed research is the method for generating tangential tensions between fluid layers, which impacts the accurate monitoring of the current hydrodynamic events. The study was based on the system of differential equations of viscous fluid flow, where viscous forces in turbulent flows were calculated using the Prandtl calculation method for stationary turbulent flows. Nevertheless, this formula could also be used in the case of unstable turbulent flows. This theory about the appearance of viscous forces in turbulent flows led to the creation of a mathematical model of the issue and the development of a method for its integration. Integration throughout the length of the inlet transition section led to the derivation of calculation formulas for the hydrodynamic properties of the current. These calculations showed the ongoing phenomena. In order to accurately design the transition sections of automatic hydrocontrolled equipment, it was crucial to understand the inlet transition section. Conclusions were drawn from the analysis of the results of computerized experimental research using the obtained analytical solutions. Scientific research and engineering applications may benefit from the study's findings.

References

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