Structure of turbulent non-isothermal flow in a pipe with a sudden expansion

U.K. Zhapbasbayev; D.Zh. Bossinov

doi:10.31643/2026/6445.13

Authors

U.K. Zhapbasbayev Satbayev University
D.Zh. Bossinov Satbayev University

DOI:

https://doi.org/10.31643/2026/6445.13

Keywords:

non-isothermal turbulent flow, viscoplastic fluid, recirculation zone of pipe flow with sudden expansion.

Abstract

The article studies a mathematical model of turbulent non-isothermal flow of non-Newtonian fluid. At the inlet, the fluid is Newtonian and, due to a decrease in temperature, it becomes non-Newtonian due to increased viscosity and yield strength. The system of turbulent motion and heat transfer equations is solved by the numerical control volume method in variables of the velocity and pressure components. The calculations yielded average and pulsation characteristics of the non-isothermal motion of non-Newtonian fluid in a pipe with sudden expansion. The calculations show a sharp reduction in the structure of the recirculation zone and a decrease in its parameters with an increase in the Bingham number Bn. In this zone, the maximum negative value of the average velocity, equal to‒Umax/Um1 ≈ 0.2 for a Newtonian fluid, decreases to ‒Umax/Um1 ≈ 0.1 at the Bingham number Bn = 17. A decrease in the turbulent characteristics of the non-Newtonian fluid flow is also observed with an increase in the Bingham number. Heat exchange characteristics in the flow region of turbulent non-Newtonian and Newtonian fluids are qualitatively similar. The location of the flow attachment and maximum heat exchange of non-Newtonian fluid does not exceed 10%. The length of the recirculation zone of viscoplastic fluid is shorter by up to 66% compared to Newtonian fluid.

Downloads

Download data is not yet available.

Author Biographies

U.K. Zhapbasbayev, Satbayev University

Doctor of Technical Sciences, Professor, Head of the Modeling in Energy Scientific and Production Laboratory, Satbayev University, Almaty, Kazakhstan. ORCID: https://orcid.org/0000-0001-5973-5149

D.Zh. Bossinov, Satbayev University

Master of natural sciences, researcher in laboratory Modeling in Energy, Satbayev University, Almaty, Kazakhstan. ORCID ID: https://orcid.org/0000-0003-3757-6460

References

So RMC. Inlet centerline turbulence effects on reattachment length in axisymmetric sudden-expansion flows, Exp. Fluids. 1987; 5:424-426.

Teyssandiert RG, Wilson MP. An analysis of flow through sudden enlargements in pipes, J. Fluid Mech. 1974; 64(1):85-95.

Tinney CE, Glauser MN, Eaton EL, Taylor JA. Low-dimensional azimuthal characteristics of suddenly expanding axisymmetric flows, J. Fluid Mech. 2006; 567:141-155.

Khezzar L, Whitelaw JH, Yianneskis M. An experimental study of round sudden expansion flows, in: Proceedings of the Fifth Symposium on turbulent shear flows, Cornell University. 1985, 5-25.

Driver DM, Seegmiller HL. Features of a reattaching turbulent shear layer in divergent channel flow, AIAA Journal. 1983; 23:163.

Stieglmeier M, Tropea C, Weiner N, NitscheW. Experimental investigation of the flow through axisymmetric expansions, ASME J. Fluids Eng. 1989; 111:464-471.

Pakhomov MA, Zhapbasbayev UK, Bossinov DZh. Numerical simulation of the transition of a Newtonian to a viscoplastic state in a turbulent flow. J. King Saud University-Sci. 2023; 35(2):102522.

Pakhomov MA, Zhapbasbayev UK. Comparative predictions of turbulent non-isothermal flow of a viscoplastic fluid with a yield stress, Heliyon. 2024; 10:e24062.

Pakhomov MA, Zhapbasbayev UK. RANS predictions of turbulent non-isothermal viscoplastic fluid in pipe with sudden expansion. J. Non-Newtonian Fluid Mech. 2024; 334:105329.

Schwedoff FN. La rigidité des fluides, Rapports du Congrès International de Physique. 1900; 1:478.

Bingham EC. Fluidity and Plasticity, McGraw-Hill, New York. 1922.

Wilkinson WL. Non-Newtonian fluids. Fluid Mechanics, Mixing and Heat Transfer, Pergamon Press, London. 1960.

Lovato S, Keetels GH, Toxopeus SL, Settels JW. An eddy-viscosity model for turbulent flows of Herschel–Bulkley fluids, J. Non-Newtonian Fluid Mech. 2022; 301:104729.

Gavrilov AA, Rudyak VY. Reynolds-averaged modeling of turbulent flows of power-law fluids, J. Non-Newton. Fluid Mech. 2016; 227:45-55.

Papanastasiou TC. Flows of materials with yield. J. Rheology. 1987; 31(5):385-404.

Fadai-Ghotbi A, Manceau R, Boree J. Revisiting URANS computations of the backward-facing step flow using second moment closures. Influence of the numerics, Flow, Turbulence and Combust. 2008; 81(3):395-410.

Poole RJ, Escudier MP. Turbulent flow of viscoelastic liquids through an axisymmetric sudden expansion, J. Non-Newtonian Fluid Mech. 2004; 117:25-46.

Pakhomov MA, Terekhov VI. Second moment closure modelling of flow, turbulence and heat transfer in droplet-laden mist flow in a vertical pipe with sudden expansion, Int. J. Heat Mass Transfer. 2013; 66:210-222.

Zhapbasbayev UK, Ramazanova GI, Bossinov DZh, Kenzhaliyev BK. Flow and heat exchange calculation of waxy oil in the industrial pipeline. Case Stud. Thermal Eng. 2021; 26:101007.

Kutateladze SS, Leont’ev AI. Heat and Mass Transfer and Friction in Turbulent Boundary Layer, Hemisphere, New York. 1989.