# Visualization of a finite wall-mounted cylinder wake controlled by a horizontal or inclined hole

### Abstract

A passive flow control technique, which is to drill a horizontal hole going from the front surface to the rear surface or an inclined hole going from the front surface to the top surface inside a circular cylinder of an aspect ratio *H*/*D* = 1, is proposed to control the rear recirculation region and the vortices near the free end surface. Here, both the diameter *D* and height *H* of cylinder are 70 mm. PIV measurement was performed with Reynolds number of 8570 in a water tunnel. Furthermore, in order to consider the effect of the hole position of the front surface, the cylinder models having different hole height of front surface from wall were tested. It is found that the rear recirculation zones of the horizontal hole cylinders are smaller than that of the standard cylinder. The Reynolds shear stresses and the turbulent kinetic energy are evidently reduced by the flow issued from the horizontal hole. Meanwhile, the instantaneous large-scale vortical structures of the rear recirculation zone are broken down into several small-scale vortices with decreasing the height of the horizontal hole. Although the rear separation zone of the inclined hole cylinder increases, the recirculation region near the free end surface decreases. The areas of large Reynolds shear stress and high turbulent kinetic energy increase in the rear recirculation zone. However, with increasing the height of the inclined hole, the Reynolds shear stress decreases.

### Graphical Abstract

## Keywords

Flow controlling hole Flow separation region Passive flow control PIV Low aspect ratio cylinder Vortex Wake## Notes

### Acknowledgements

The second author (AR) wishes to acknowledge support given to him by Grant-in-Aid for Scientific Research (C) (No. 16K06067) from the Japanese Society for the Promotion of Science and Natural Science Foundation of China (Grant Nos. 11721202 and 11772035).

## References

- Adaramola MS, Akinlade OJ, Sumner D, Bergstrom DJ, Schenstead AJ (2006) Turbulent wake of a finite circular cylinder of small aspect ratio. J Fluids Struct 22:919–928CrossRefGoogle Scholar
- Ali M, Doolan C, Wheatley V (2013) Aeolian tones generated by a square cylinder with a detached flat plate. AIAA J 51(2):291–301CrossRefGoogle Scholar
- Choi H, Jeon W, Kim J (2008) Control of flow over a bluff body. Annu Rev Fluid Mech 40:113–139MathSciNetCrossRefMATHGoogle Scholar
- Gonçalves RT, Franzini GR, Rosetti GF, Meneghini JR, Fujarra ALC (2015) Flow around circular cylinders with very low aspect ratio. J Fluids Struct 54:122–141CrossRefGoogle Scholar
- Hearst RJ, Guillaume G, Bharath G (2016) Effect of turbulence on the wake of a wall-mounted cube. J Fluid Mech 804:513–530MathSciNetCrossRefGoogle Scholar
- Hu C, Koterayama W (1994) Numerical study on a two-dimensional circular cylinder with a rigid and an elastic splitter plate in uniform flow. Int J Offshore Polar Eng 4:193–199Google Scholar
- Johnston CR, Wilson DJ (1996) A vortex pair model for plume downwash into stack wakes. Atmos Environ 31:13–20CrossRefGoogle Scholar
- Kawamura T, Hiwada M, Hibino T, Mabuchi T, Kumada M (1984a) Flow around a finite circular cylinder on a flat plate. Bull JSME 27:2142–2150CrossRefGoogle Scholar
- Kawamura T, Hiwada M, Hibino T, Mabuchi T, Kumada M (1984b) Flow around a finite circular on flat plate: in the case of cylinder length larger than turbulent boundary layer thickness. Trans JSME 50:332–341
**(in Japanese)**CrossRefGoogle Scholar - Krajnović S (2011) Flow around a tall finite cylinder explored by large eddy simulation. J Fluid Mech 676:294–317MathSciNetCrossRefMATHGoogle Scholar
- Lee LW (1997) Wake structure behind a circular cylinder with a free end. In: Proceedings of the Heat Transfer and Fluid Mechanics Institute, pp 241–251Google Scholar
- Lim HC, Lee SJ (2003) PIV measurements of near wake behind a U-grooved cylinder. J Fluids Struct 18:119–130CrossRefGoogle Scholar
- New TH, Shi SG, Liu YZ (2015) On the flow behavior of confined finite-length wavy cylinders. J Fluids Struct 54:281–296CrossRefGoogle Scholar
- Okamoto T, Yagita M (1973) The experimental investigation on the flow past a circular cylinder of finite length placed normal to the plane surface in a uniform stream. Bull JSME 16:805–814CrossRefGoogle Scholar
- Oruc V (2012) Passive control of flow structures around a circular cylinder by using screen. J Fluids Struct 33:229–242CrossRefGoogle Scholar
- Ozkana GM, Firatb E, Akilli H (2017) Passive flow control in the near wake of a circular cylinder using attached permeable and inclined short plates. Ocean Eng 134:35–49CrossRefGoogle Scholar
- Pattenden RJ, Turnock SR, Zhang X (2005) Measurements of the flow over a low-aspect-ratio cylinder mounted on a ground plane. Exp Fluids 39:10–21CrossRefGoogle Scholar
- Porteous R, Moreau DJ, Doolan CJ (2014) A review of flow-induced noise from finite wall-mounted cylinders. J Fluids Struct 51:240–254CrossRefGoogle Scholar
- Rashidi S, Hayatdavoodi M, Esfahani JA (2016) Vortex shedding suppression and wake control: a review. Ocean Eng 126:57–80CrossRefGoogle Scholar
- Rinoshika H, Rinoshika A, Fujimoto S (2017) Passive control on flow structure around a wall-mounted low aspect ratio circular cylinder by using an inclined hole. J Fluid Sci Tech 12(1):JFST0006CrossRefGoogle Scholar
- Rinoshika A, Zhou Y (2005) Orthogonal wavelet multi-resolution analysis of a turbulent cylinder wake. J Fluid Mech 524:229–248CrossRefMATHGoogle Scholar
- Rinoshika A, Zhou Y (2009) Reynolds number effects on wavelet components of self-preserving turbulent structures. Phys Rev E 79(046322):1–11Google Scholar
- Roh SC, Park SO (2003) Vortical flow over the free end surface of a finite circular cylinder mounted on a flat plate. Exp Fluids 34:63–67CrossRefGoogle Scholar
- Rostamy N, Sumner D, Bergstrom DJ, Bugg JD (2012) Local flow field of a surface-mounted finite circular cylinder. J Fluids Struct 34:105–122CrossRefGoogle Scholar
- Sumner D (2013) Flow above the free end of a surface-mounted finite-height circular cylinder: a review. J Fluids Struct 43:41–63CrossRefGoogle Scholar
- Sumner D, Heseltine JL, Dansereau OJP (2004) Wake structure of a finite circular cylinder of small aspect ratio. Exp Fluids 37:720–730CrossRefGoogle Scholar
- Tanaka S, Murata S (1999) An investigation of the wake structure and aerodynamic characteristics of a finite circular cylinder. JSME Int J B 42:178–187CrossRefGoogle Scholar
- Wang HF, Zhou Y (2009) The finite-length square cylinder near wake. J Fluid Mech 638:453–490CrossRefMATHGoogle Scholar
- Wang H, Zhou Y, Chan CK, Lam KS (2006) Effect of initial conditions on interaction between boundary layer and a wall-mounted finite-length-cylinder wake. Phys Fluids 18:065106CrossRefGoogle Scholar