Annotation

Purpose: to determine the effect of small interpipe distances (1D–4D) on the flow structure and hydrodynamic loads while flowing round two parallel pipelines. 

Materials and methods. Experimental studies of the vertical flow velocity distribution were conducted in various cross-sections: on the approach to the transition, in a close proximity of the pipelines, behind the pipelines, and in the shell side – on a hydraulic channel in the Hydraulics and Hydromechanics Laboratory of the Moscow State University of Civil Engineering. Numerical simulation of the free-stream flowing round the pipeline crossing with incoming flow was performed using the ANSYS Fluent software package. Pipeline models for the laboratory experiment were made of plastic, the diameter of the models was 25 mm, the surface roughness was simulated using № 100 sandpaper with an equivalent roughness peak height of 100 μm. In numerical simulations, the SST model was used to describe turbulence, and the free surface was taken into account using the VOF method. The developed mathematical model was verified by comparing the numerical simulation results with experimental data obtained in a study of flowing round a pipeline located at the bottom of a hydraulic flume. 

Results. It was found that, for interpipe distances in the 1D–3D range, a trace zone forms behind the first pipe, maintaining a significant influence on the second pipe and causing a decrease in uplift force and the appearance of a negative longitudinal induced lift drag component. As the interpipe distance increases to 4D, a transition to a regime of virtually independent flow is observed, accompanied by the restoration of the flow structure ahead of the second pipe. 

Conclusions. An interpipe distance of approximately 4D can be considered rational for reducing the mutual hydrodynamic influence of parallel lines of an underwater pipeline. 

doi: 10.31774/2712-9357-2026-16-2-318-336

For quoting

Sherstnev D. Yu., Bryanskaya Yu. V. Hydrodynamic interaction of two parallel pipelines with small interpipe distances. Land Reclamation and Hydraulic Engineering. 2026;16(2):318–336. (In Russ.). https://doi.org/10.31774/2712-9357-2026-16-2-318-336.

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