Computational Simulation and Experimentation of Fluid Flow Characteristics in Expansion U-Loop Model Pipes

Nasaruddin Salam; Rustan Tarakka; Bambang Bakri; Lukman Kasim; Muhammad Hidayat Bin Jamal

doi:10.48084/etasr.14258

Authors

Nasaruddin Salam Mechanical Engineering Department, Faculty of Engineering, Hasanuddin University, Gowa, Indonesia https://orcid.org/0000-0003-4213-531X
Rustan Tarakka Mechanical Engineering Department, Faculty of Engineering, Hasanuddin University, Gowa, Indonesia https://orcid.org/0000-0002-6083-650X
Bambang Bakri Civil Engineering Department, Faculty of Engineering, Hasanuddin University, Gowa, Indonesia https://orcid.org/0000-0001-9006-2018
Lukman Kasim Mechanical Engineering Department, Faculty of Engineering, Hasanuddin University, Gowa, Indonesia https://orcid.org/0000-0002-9777-2749
Muhammad Hidayat Bin Jamal Faculty of Engineering, School of Civil Engineering, University Teknologi Malaysia (UTM), Malaysia

Volume: 15 | Issue: 6 | Pages: 30175-30184 | December 2025 | https://doi.org/10.48084/etasr.14258

Received: 24 August 2025 | Revised: 15 September 2025 and 11 October 2025 | Accepted: 13 October 2025 | Online: 8 December 2025

Corresponding author: Lukman Kasim

Abstract

A pipe’s geometry plays a critical role in determining both flow behavior and structural support performance, making it an essential consideration in industrial piping design. Among the various modifications applied in practice, the expansion U-loop is one of the most significant, as it directly influences the pressure losses, flow distribution, and stress conditions. This study investigates the flow characteristics of U-loop expansion pipes through a dual approach that combines computational simulations and experimental testing. The computational study was carried out using Computational Fluid Dynamics (CFD) simulations with ANSYS FLUENT 6.3.26, involving three U-loop models fabricated from galvanized iron, with a wall thickness of 1.2 mm. Two of the models featured equal leg heights, whereas the third employed an asymmetric configuration, with one leg twice the length of the other. To ensure reliability, experiments were conducted under identical boundary conditions at five inlet velocities ranging from 5.0 to 7.0 m/s, with each case repeated three times. Pressure taps were strategically installed along the loop to measure fluid pressure and obtain a detailed distribution profile, particularly at nodes 1, 3, and 7. The results of the simulations and experiments were compared, showing an average validation error of only 3%. The originality of this study lies in combining CFD and direct experimental testing on U-loop models with varied straight-segment lengths, offering valuable insights into the pressure distribution and flow patterns that have not been extensively examined.

Keywords:

U-loop pipe expansion, flow pressure distribution, low velocity, pipe hoop stress, longitudinal stress

Downloads

Download data is not yet available.

References

M. A. W. Adhicahya, N. Salam, and R. Tarakka, "Pipe Stress Analysis of Pertalite Fuel Discharge Pipeline PT Pertamina Patra Niaga Integrated Terminal Makassar," Prosiding Seminar Nasional Tahunan Teknik Mesin, vol. 21, pp. 160–167.

P. Mahardhika, A. W. Husodo, G. E. Kusuma, R. D. E. Witjonarko, and E. N. Budiyanto, "Analysis of Symmetrical and Nonsymmetrical Vertical Expansion Loop to Increase Flexibility And Reduce Pipe Stress Based On ASME B31.3," TEKNIK, vol. 42, no. 1, pp. 63–70, May 2021. DOI: https://doi.org/10.14710/teknik.v42i1.29244

M. Haq and B. Riyandwita, "Analysis of the Effect of Variations in Expansion Loop Shapes on Pressure Drops Occurring in the Flow of Crude Oil in Pipeline Using Computational Fluid Dynamics," presented at International Conference on Sustainable Engineering, Infrastructure and Development, ICO-SEID 2022, Jakarta, Indonesia, Dec. 2023. DOI: https://doi.org/10.4108/eai.23-11-2022.2341543

Y. Elahibakhsh, "Innovative Approaches to Expansion Loop Design for Enhanced Piping System Durability," American Journal of Mechanical and Materials Engineering, vol. 8, no. 2, pp. 25–32, Sep. 2024. DOI: https://doi.org/10.11648/j.ajmme.20240802.11

P. Pujiyanto, H. Yudo, and S. J. Sisworo, "Desain dan Analisa Kekuatan Pipa Expansion Loops dengan Variasi Ukuran Loop dan Bentuk Loop," Jurnal Teknik Perkapalan, vol. 9, no. 2, pp. 145–151, Jan. 2021.

T. F. Nugroho, E. M. Wardhana, and R. N. Azmi, "Stress Analysis of Land Subsidence Effect on Header Pipe 12 Inch in LPG Station Semarang," International Journal of Marine Engineering Innovation and Research, vol. 2, no. 4, pp. 261–268, Sep. 2018. DOI: https://doi.org/10.12962/j25481479.v2i4.4069

ASME B31.3 Process Piping Guide. American Society of Mechanical Engineers, 2012.

H. Yudo, S. Jokosisworo, W. Amiruddin, P. Pujianto, T. Tuswan, and M. Djaeni, "Numerical evaluation of expansion loops for pipe subjected to thermal displacements," Curved and Layered Structures, vol. 9, no. 1, pp. 72–80, Jan. 2022. DOI: https://doi.org/10.1515/cls-2022-0007

B. Shehadeh, S. I. Ranganathan, and F. H. Abed, "Optimization of piping expansion loops using ASME B31.3," Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering, vol. 230, no. 1, pp. 56–64, Feb. 2016. DOI: https://doi.org/10.1177/0954408914532808

C. Cholca, W. Quitiaquez, E. Pilataxi, and F. Toapanta, "Evaluation of Flexible Configuration Pipeline Networks for Hydrocarbon Transportation," Revista Técnica energía, vol. 20, no. 1, pp. 100–108, Dec. 2023. DOI: https://doi.org/10.37116/revistaenergia.v20.n1.2023.584

B. Debtera, "Computational Fluid Dynamics Simulation and Analysis of Fluid Flow in Pipe: Effect of Fluid Viscosity," Social Science Research Network, Aug. 2022. DOI: https://doi.org/10.2139/ssrn.4201717

R. K. Apalowo and C. J. Akisin, "CFD-based investigation of turbulent flow behavior in 90-deg pipe bends," Journal of Applied Research in Technology & Engineering, vol. 5, no. 2, pp. 53–62, Mar. 2024. DOI: https://doi.org/10.4995/jarte.2024.20665

M. W. Khalid and M. Ahsan, "Computational Fluid Dynamics Analysis of Compressible Flow Through a Converging-Diverging Nozzle using the k-ε Turbulence Model," Engineering, Technology & Applied Science Research, vol. 10, no. 1, pp. 5180–5185, Feb. 2020. DOI: https://doi.org/10.48084/etasr.3140

O. Y. Wei and S. U. Masuri, "Computational Fluid Dynamics Analysis on Single Leak and Double Leaks Subsea Pipeline Leakage," CFD Letters, vol. 11, no. 2, pp. 95–107, 2019.

M. A. Asri et al., "Flow Characteristics for Leak Detection in Oil and Gas Pipeline Network Using CFD Simulations," Journal of Design for Sustainable and Environment, vol. 4, no. 1, pp. 1–8, 2022.

A. A. Abuhatira, S. M. Salim, and J. B. Vorstius, "CFD-FEA based model to predict leak-points in a 90-degree pipe elbow," Engineering with Computers, vol. 39, no. 6, pp. 3941–3954, Dec. 2023. DOI: https://doi.org/10.1007/s00366-023-01853-4

H. Fu, L. Yang, H. Liang, S. Wang, and K. Ling, "Diagnosis of the single leakage in the fluid pipeline through experimental study and CFD simulation," Journal of Petroleum Science and Engineering, vol. 193, Oct. 2020, Art. no. 107437. DOI: https://doi.org/10.1016/j.petrol.2020.107437

L. C. Peng and T. L. Peng, Pipe Stress Engineering. American Society of Mechanical Engineers, 2009. DOI: https://doi.org/10.1115/1.802854

P. F. Mushumbusi, A. Chaudhari, J. Leo, and V. G. Masanja, "CFD Analysis of Flow Characteristics and Diagnostics of Leaks in Water Pipelines," Engineering, Technology & Applied Science Research, vol. 14, no. 5, pp. 16272–16280, Oct. 2024. DOI: https://doi.org/10.48084/etasr.8146

Z. Huda and M. H. Ajani, "Evaluation of Longitudinal and Hoop Stresses and a Critical Study of Factor of Safety (FoS) in Design of a Glass-Fiber Pressure Vessel," International Journal of Materials and Metallurgical Engineering, vol. 9, no. 1, pp. 39–42, Jan. 2015.