Document Type : Research Paper


Mechanical Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.


In this study, natural heat convection caused by centric and vertically eccentric long horizontal cylinders under the influence of vibration is experimentally investigated. The internal wall of the annulus is heated and kept at a constant heat flux, while the outside wall is cooled and maintained at a constant temperature. The vibration frequency impacts the annular convection heat transfer process and the effects of the Rayleigh number, heat flow, and eccentricity. This work employed a moderate, laminar-ranging Rayleigh number from (5×104 to 6.48×106), while the eccentricity range is varied from (-0.667, 0, and+0.667). The investigation is carried out at five different frequencies (0, 2, 5, 10, 15, and 20 Hz); therefore, it was decided to compare the case under the same circumstances in both the absence and presence of vibration. The present results' verification worked exceptionally well in concordance with previous studies. When heat fluxes are considered, the study demonstrates that the temperature difference along the gap (radial difference) between the two cylinders significantly decreases for negative as opposed to positive eccentricities for each Rayleigh number. For different eccentricities, it was discovered that the temperature difference decreased as the Rayleigh number increased. Along with these reductions, the temperature difference was promoted as the vibration frequency increased, which is significant at (20 Hz) within the range considered for controlling parameters. It was also observed that the decrease in temperature difference is higher for the negative eccentric position than for the centric and positive positions. At vertical positive eccentricity at a low Rayleigh number, the gain in vibrational average Nusselt number caused by applying vibration had a minimum value of 22.50601475%, While at the higher value of the Rayleigh number, the maximum increase in negative vertical eccentricity was 86.66933125%. However, the gain in the average Nusselt number depends on the position of the heated inner cylinder, the Rayleigh number, and the vibrational frequency. 

Graphical Abstract


  • Heat transfer rate from vibrated heated inner cylinder increased with increased vibration intensity.
  • After a critical value of vibrational inner cylinder heat transfer decreased.
  • The decrease in temperature difference is higher for the negative eccentric position than for the centric and positive positions.


Main Subjects

  1. Hosseini, A. Rezania, M. Alipur, and L. A. Rosendahl, Natural Convection Heat Transfer from a Long Heated Vertical Cylinder to an Adjacent Air Gap of Concentric and Eccentric Conditions, Heat Mass Transfer, 48 (2012) 55-60.
  2. Shokouhmand, S.M.A. Noori Rahim Abadi, and A. Jafari, The effect of the horizontal vibrations on natural heat transfer from an isothermal array of cylinders, Int. J. Mech. Mater. Des., 7 (2011) 313-326.
  3. B. Baxi, N.a.Ramachandra, Effect of Vibration on Heat Transfer from Spheres, Winter Annu. Meet. New York, N.Y.I, 68, 1968.
  4. E. Forbes, C. T. Carley, and C. J. Bell, Vibration effects on convective heat transfer in enclosures, ASME(1970), J. Heat Transfer, 92 (1970) 429-438.
  5. Wu Shung and S. W. Jiann, A study of thermal convection in an enclosure induced simultaneously by gravity and vibration, Int. J. Heat Mass Transfer,  35 (1992) 1695-1710.
  6. S. Fu and W. J. Shieh, Transient thermal convection in an enclosure induced simultaneously by gravity and vibration, Int. J. Heat Mass Transfer, 36(1993) 437-452.
  7. H. Al-Ubaydi, Study of Influence of Vertical Vibration on Heat Transfer Coefficient by Free Convection from Cylinders, M. Sc. Thesis, University of Technology, 2001.
  8. Shakir, Experimental study of the effect of vibrations on the free convection heat transfer coefficient from an annular finned cylinder, MSc Thesis, University of Technology, 2007.
  9. M. Alawadhi, Natural convection flow in a horizontal annulus with an oscillating inner cylinder using Lagrangian–Eulerian kinematics. Comput. Fluids, 37 (2008) 1253–1261.
  10. R. Sarhan, Vertical Forced Vibration Effect on Natural Convective Performance Longitudinal Fin Heat Sinks, Tikrit J. Eng. Sci., 20 (2013) 60-69.
  11. A. Tawfik, A. Mohammed, H.Z. Zain, Effect of Vibration on the Heat Transfer Process in the Developing Region of Annulus with Rotating Inner Cylinder, Eng. Technol. J., 33 (2015) 590-611.
  12. K. Dawood, H.A. Mohammed, N. A. Che Sidik, K. M. Munisamy, M. A. Wahid, Forced, natural and mixed-convection heat transfer and fluid flow in annulus: A review, Int. Commun. Heat Mass Transfer, 62 (2015) 45-57.
  13. K. Kadhim, H.O. Mery, Influence of Vibration on Free Convection Heat transfer from Sinusoidal Surface, Int. J. Comput. Appl. Technol., 136 (2016) 1-6.
  14. Hosseinian, A.H.M. Isfahani, and E.Shirani, Experimental investigation of surface vibration effects on increasing the stability and heat transfer coefficient of MWCNTs-water nanofluid in a flexible double pipe heat exchanger, Exp. Therm Fluid Sci., 90 (2018) 275-285.
  15. K. Murad, H.D. Lafta, S.E. Abdullah, the Effect of Transverse Vibration on the Natural Convection Heat Transfer in a Rectangular Enclosure, Int. J. Mech. Eng. Technol., 10 (2019) 266-277.
  16. Laidoudi, M. Helmaoui, M. Bouzit, and A. Ghenaim, Natural convection of Newtonian fluids between two concentric cylinders of a special cross-sectional form. Therm. Sci., 25 (2021) 3701-3714.
  17. Laidoudi, Enhancement of natural convection heat transfer in concentric annular space using inclined elliptical cylinder, J. Nav. Archit. Mar. Eng., 17 (2020) 89–99.
  18. Laidoudi, The role of concave walls of inner cylinder on natural convection in annular space, Acta Mech. Malaysia, 3 (2020) 24-28.
  19. Laidoudi, Natural convection from four circular cylinders in across arrangement within horizontal annular space, Acta Mech. Autom., 14 (2020), 98-102.
  20. Laidoudi, H. Ameur, Investigation of the mixed convection of power-law fluids between two horizontal concentric cylinders: Effect of various operating conditions, Therm. Sci. Eng. Prog., 20 (2020)100731.
  21. M. Al-azzawi, A.R. abdullah, B.M. Majel, L. J. Habeeb, Experimental Investigation of the Effect of Forced Vibration on Natural Convection Heat Transfer in a Concentric Vertical Cylinder, J. Mech. Eng. Res. Dev., 44 (2021) 56-65.
  22. H. Kuehn and R.J.Goldstein, An experimental and theoretical study of natural convection in the annulus between horizontal concentric cylinders, J. Fluid Mech., 74 (1976) 695-719.
  23. H. Kuehn and R.J.Goldstein, an Experimental Study of Natural Convection in Concentric and Eccentric Horizontal Cylindrical Annuli, ASME, J. Heat Transfer, 100 (1979) 635-640.
  24. Projahn, H.Rieger, and H.Beer, Numerical Analysis of Lminar Natural Convection between Concentric and Eccentric Cylinders, Numer. Heat Transfer, 4 (1981) 131-146.
  25. Naylor, H. M. Badrand, J.D. Tarasuk, Experimental and Numerical Study of Natural Convection between Two Eccentric Tubes, Int. J. Heat Mass Transfer, 32 (1989) 171-181.
  26. A.W.Hamed, Experimental Study of Natural Convection Heat Transfer in Inclined Cylindrical Annulus, Sol. Wind Technol., 6 (1989) 573-579.
  27. Cengle, Y.A., Heat Transfer Practical Approach, International edition WCB/McGraw-Hill, 1998.
  28. Venkateshan SP, Mechanical measurements, 2nd ed. Ane Books Pvt.Ltd, India, 2015.
  29. Measurement Uncertainty, International Atomic Energy Agency, IAEATECDOC-1585, May 2008.
  30. J. Kline, F.A. McClintock, Describing uncertainties in single sample experiment, Mech. Eng., 175 (1953) 3-8.
  31. J. Kline, The purpose of uncertainty analysis, J. Fluids Eng., 107 (1985)153-160.
  32. K. Nag, and A. Bhattacharya, Effect of Vibration on Natural Convection Heat Transfer From Vertical Fin Arrays, Lett. Heat Mass Transf., 99 (1982) 478-498.