Wind and Structures

  • 제34권1호
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  • Pages.115-125
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  • 2022
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  • 1226-6116(pISSN)
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  • 1598-6225(eISSN)
테크노프레스 (Techno-Press)
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DOI QR코드

DOI QR Code

Impact of the lateral mean recirculation characteristics on the near-wake and bulk quantities of the BARC configuration

  • 투고 : 2021.05.16
  • 심사 : 2021.07.21
  • 발행 : 2022.01.25
⟨ 이전 논문 다음 논문 ⟩

초록

The high-Reynolds number flow around a rectangular cylinder, having streamwise to crossflow length ratio equal to 5 is analyzed in the present paper. The flow is characterized by shear-layer separation from the upstream edges. Vortical structures of different size form from the roll-up of these shear layers, move downstream and interact with the classical vortex shedding further downstream in the wake. The corresponding mean flow is characterized by a recirculation region along the lateral surface of the cylinder, ending by mean flow reattachment close to the trailing edge. The mean flow features on the cylinder side have been shown to be highly sensitive to set-up parameters both in numerical simulations and in experiments. The results of 21 Large Eddy Simulations (LES) are analyzed herein to highlight the impact of the lateral mean recirculation characteristics on the near-wake flow features and on some bulk quantities. The considered simulations have been carried out at Reynolds number Re=DU_∞/ν=40 000, being D the crossflow dimension, U_∞ the freestream velocity and ν the kinematic viscosity of air; the flow is set to have zero angle of attack. Some simulations are carried out with sharp edges (Mariotti et al. 2017), others with different values of the rounding of the upstream edges (Rocchio et al. 2020) and an additional LES is carried out to match the value of the roundness of the upstream edges in the experiments in Pasqualetto et al. (2022). The dimensions of the mean recirculation zone vary considerably in these simulations, allowing us to single out meaningful trends. The streamwise length of the lateral mean recirculation and the streamwise distance from the upstream edge of its center are the parameters controlling the considered quantities. The wake width increases linearly with these parameters, while the vortex-shedding non-dimensional frequency shows a linear decrease. The drag coefficient also linearly decreases with increasing the recirculation length and this is due to a reduction of the suctions on the base. However, the overall variation of C_D is small. Finally, a significant, and once again linear, increase of the fluctuations of the lift coefficient is found for increasing the mean recirculation streamwise length.

키워드

과제정보

The authors wish also to thank CINECA computing center (Bologna, Italy) for the computational resources under ISCRA programs (class C projects "BARCCORN" and "ROUNDREC").

참고문헌

  1. Bearman, P.W. (1965), "Investigation of the flow behind a twodimensional model with blunt trailing edge and fitted with splitter plates", J. Fluid Mech., 21, 241-255. https://doi.org/10.1017/S0022112065000162.
  2. Bearman, P.W. (1967), "On vortex street wakes", J. Fluid Mech., 28, 625-641. https://doi.org/10.1017/S0022112067002368.
  3. Bruno, L., Coste, N. and Fransos, D. (2012), "Simulated flow around a rectangular 5:1 cylinder: spanwise discretisation effects and emerging flow features", J. Wind Eng. Ind. Aerod., 104-106, 203-215. https://doi.org/10.1016/j.jweia.2012.03.018.
  4. Bruno, L., Fransos, D., Coste, N. and Bosco, A. (2010), "3D flow around a rectangular cylinder: a computational study", J. Wind Eng. Ind. Aerod., 98(6-7), 263-276. https://doi.org/10.1016/j.jweia.2009.10.005.
  5. Bruno, L., Salvetti, M.V. and Ricciardelli, F. (2014), "Benchmark on the aerodynamics of a rectangular 5:1 cylinder: and overview after the first four years of activity", J. Wind Eng. Ind. Aerod., 126, 87-106. https://doi.org/10.1016/j.jweia.2014.01.005.
  6. Buresti, G. (1983), "Appraisal of universal wake numbers from data for roughened circular cylinders", J. Fluids Eng., 105, 464-468. https://doi.org/10.1115/1.3241031.
  7. Chiarini, A. and Quadrio, M. (2021), "The turbulent flow over the BARC rectangular cylinder: A DNS study", Flow, Turbulence Combustion. https://doi.org/10.1007/s10494-021-00254-1.
  8. Cimarelli, A., Leonforte, A. and Angeli, D. (2018), "Direct numerical simulation of the flow around a rectangular cylinder at a moderately high Reynolds number", J. Wind Eng. Ind. Aerod., 174, 39-49. https://doi.org/10.1016/j.jweia.2017.12.020.
  9. Cimarelli, A., Leonforte, A. and Angeli, D. (2018), "On the structure of the self-sustaining cycle in separating and reattaching flows", J. Fluid Mech., 857, 907-936. https://doi.org/10.1017/jfm.2018.772.
  10. Domarazdki, J.A. (2010), "Large eddy simulations without explicit eddy viscosity models", Int. J. Comput. Fluid Dyn., 24(10), 435-447. https://doi.org/10.1080/10618562.2010.535792.
  11. Fischer, P. and Mullen, J. (2001), "Filter-based stabilization of spectral element methods", C. R. Acad. Sci. I-Math., 332(1), 265-270. https://doi.org/10.1016/S0764-4442(00)01763-8.
  12. Fischer, P.F., Lottes, J.W. and Kerkemeier, S.G. (2008), "nek5000 Web page", http://nek5000.mcs.anl.gov
  13. Griffin, O.M. (1978), "A universal number for the ''locking-on'' of vortex shedding to the vibrations of bluff cylinders", J. Fluid Mec., 85, 591-606. https://doi.org/10.1017/S0022112078000804.
  14. Kiya, M. and Sasaki, K. (1983), "Free-stream turbulence effects on separation bubble", J. Wind Eng. Ind. Aerod., 14(1-3), 375-398. https://doi.org/10.1016/0167-6105(83)90039-9.
  15. Maday Y., Patera A.T. and Ronquist E.M. (1990), "An Operatorintegration- factor splitting method for time-dependent problems: Application to incompressible fluid flow", J. Scientific Comput., 5(4), 263-292. https://doi.org/10.1007/BF01063118.
  16. Mannini, C., Mariotti, A., Siconolfi, L. and Salvetti, M.V. (2019), "Benchmark on the aerodynamics of a 5:1 Rectangular cylinder: further experimental and LES results", ERCOFTAC Series, 25, 427-432. https://doi.org/10.1007/978-3-030-04915-7_56.
  17. Mannini, C., Marra, A.M., Pigolotti, L. and Bartoli, G. (2017), "The effects of free-stream turbulence and angle of attack on the aerodynamics of a cylinder with rectangular 5:1 cross section", J. Wind Eng. Ind. Aerod., 161, 42-58. https://doi.org/10.1016/j.jweia.2016.12.001.
  18. Mariotti, A. (2018), "Axisymmetric bodies with fixed and free separation: base pressure and near-wake fluctuations", J. Wind Eng. Ind. Aerod., 176, 21-31. https://doi.org/10.1016/j.jweia.2018.03.003.
  19. Mariotti, A. and Buresti, G. (2013), "Experimental investigation on the influence of boundary layer thickness on the base pressure and near-wake flow features of an axisymmetric bluntbased body", Experimen. Fluids, 54, 1612. https://doi.org/10.1007/s00348-013-1612-5.
  20. Mariotti, A., Buresti, G. and Salvetti, M.V. (2014), "Control of the turbulent flow in a plane diffuser through optimized contoured cavities", Europ. J. Mech./B Fluids, 48, 254-265. https://doi.org/10.1016/j.euromechflu.2014.04.009.
  21. Mariotti, A., Buresti, G. and Salvetti, M.V. (2015), "Connection between base drag, separating boundary layer characteristics and wake mean recirculation length of an axisymmetric bluntbased body", J. Fluids Struct., 55, 170-192. https://doi.org/10.1016/j.jfluidstructs.2015.02.012.
  22. Mariotti, A., Buresti, G. and Salvetti, M.V. (2015), "Use of multiple local recirculations to increase the efficiency in diffusers", Europ. J. Mech./B Fluids, 50, 27-37. https://doi.org/10.1016/j.euromechflu.2014.11.004.
  23. Mariotti, A., Buresti, G. and Salvetti, M.V. (2019), "Separation delay through contoured transverse grooves on a 2D boat-tailed bluff body: Effects on drag reduction and wake flow features", Europ. J. Mech. B/Fluids, 74, 351-362. https://doi.org/10.1016/j.euromechflu.2018.09.009.
  24. Mariotti, A., Buresti, G., Gaggini, G. and Salvetti, M.V. (2017), "Separation control and drag reduction for boat-tailed axisymmetric bodies through contoured transverse grooves", J. Fluid Mech., 832, 514-549. https://doi.org/10.1017/jfm.2017.676.
  25. Mariotti, A., Grozescu, A.N., Buresti, G. and Salvetti, M.V. (2013), "Separation control and efficiency improvement in a 2D diffuser by means of contoured cavities", Europ. J. Mech./B Fluids, 41, 138-149. https://doi.org/10.1016/j.euromechflu.2013.03.002.
  26. Mariotti, A., Rocchio, B., Pasqualetto, E., Mannini, C. and Salvetti, M.V. (2020), "Flow around a 5:1 rectangular cylinder: Effects of the rounding of the upstream corners", ERCOFTAC Series, 27, 85-90. https://doi.org/10.1007/978-3-030-42822-8_11.
  27. Mariotti, A., Salvetti, M.V., Shoebi-Omrani, P. and Witteveen, J.A.S. (2016), "Stochastic analysis of the impact of freestream conditions on the aerodynamics of a rectangular 5:1 cylinder", Comput. Fluids, 136, 170-192. https://doi.org/10.1016/j.compfluid.2016.06.008.
  28. Mariotti, A., Siconolfi, L. and Salvetti, M.V. (2017), "Stochastic sensitivity analysis of large-eddy simulation predictions of the flow around a 5:1 rectangular cylinder", Europ. J. Mech./B Fluids, 62, 149-165. https://doi.org/10.1016/j.euromechflu.2016.12.008.
  29. Matsumoto, M. (1996), "Aerodynamic damping of prisms", J. Wind Eng. Ind. Aerod., 59(2-3), 159-175. https://doi.org/10.1007/978-3-030-42822-8_11.
  30. Moore, D.M., Letchford, C.W. and Amitay, M. (2019), "Energetic scales in a bluff body shear layer", J. Fluid Mech., 875, 543-575. https://doi.org/10.1017/jfm.2019.480.
  31. Nguyen, D.T., Hargreaves, D.M. and Owen, J.S. (2018), "Vortexinduced vibration of a 5:1 rectangular cylinder: A comparison of wind tunnel sectional model tests and computational simulations", J. Wind Eng. Ind. Aerod., 175, 1-16. https://doi.org/10.1016/j.jweia.2018.01.029.
  32. Pasqualetto, E., Lunghi, G., Rocchio, B., Mariotti, A. and Salvetti, M.V. (2022), "Experimental characterization of the lateral and near-wake flow for the BARC configuration", Wind Struct., 34(1).
  33. Patruno, L., Ricci, M., de Miranda and S. and Ubertini, F. (2016), "Numerical simulation of a 5:1 rectangular cylinder at non-null angles of attack", J. Wind Eng. Ind. Aerod., 151, 146-157. https://doi.org/10.1016/j.jweia.2016.01.008.
  34. Ricci, M., Patruno, L., de Miranda, S. and Ubertini, F. (2017), "Flow field around a 5:1 rectangular cylinder using LES: Influence of inflow turbulence conditions, spanwise domain size and their interaction", Comput. Fluids, 149, 181-193. https://doi.org/10.1016/j.compfluid.2017.03.010.
  35. Rocchio, B. Mariotti, A. and Salvetti, M.V. (2020), "Flow around a 5:1 rectangular cylinder: Effects of upstream-edge rounding", J. Wind Eng. Ind. Aerod., 204, 104237. https://doi.org/10.1016/j.jweia.2020.104237.
  36. Schewe, G. (2013), "Reynolds-number-effects in flow around a rectangular cylinder with aspect ratio 1:5", J. Fluids Struct., 39, 15-26. https://doi.org/10.1016/j.jfluidstructs.2013.02.013.
  37. Wu, B., Li, S., Li, K. and Zhang, L. (2020), "Numerical and experimental studies on the aerodynamics of a 5:1 rectangular cylinder at angles of attack", J. Wind Eng. Ind. Aerod., 119, 104097. https://doi.org/10.1016/j.jweia.2020.104097.
  38. Zhang, Z. and Xu, F. (2020), "Spanwise length and mesh resolution effects on simulated flow around a 5:1 rectangular cylinder", J. Wind Eng. Ind. Aerod., 202, 104186. https://doi.org/10.1016/j.jweia.2020.104186.