The Discrete Vortex Method for estimating how surface roughness affects aerodynamic drag acting on a long cylinder exposed to wind

Tomasz Nowicki

Abstrakt

This paper focuses on the aerodynamic drag force that acts on a long cylinder standing up to aerodynamic wind in the critical regime of the fluid flow. The core problem addressed here is how surface roughness of a high level and further increase of that level affects the drag. The research is based on computer simulations using the Discrete Vortex Method. A meshless version of the method was applied in order to let the boundary layer form freely in the way of a direct computer simulation. Fundamental ideas behind the Discrete Vortex Method, the original research program and the obtained results are presented. The main conclusion is that a small level of surface roughness may be neglected in engineering estimations.

Słowa kluczowe: wind engineering, discrete vortex method, surface roughness, aerodynamic force, aerodynamic drag
References

[1] L ewis R.I., Vortex element methods for fluid dynamic analysis of engineering systems, Cambridge University Press, 2005.

[2] T urkiyyah G., Reed D., Yang J., Fast vortex methods for predicting wind – induced pressures on buildings, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 58, 1995.

[3] T aylor I., Vezza M., Predition of unsteady flow around square and rectangular section cylinder using a discrete vortex method, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 82, 1999, 247-269.

[4] L arsen A., Walther J.H., Aeroelastic analysis of bridge girder sections based on discrete vortex simulation, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 67-68, 1997.

[5] N owicki T., Influence of boundary condition implementation in discrete vortex method on aeroelastic response of bridge decks, Monografie – Politechnika Lubelska, Lublin 2012 (in Polish).

[6] A chnebach E., Influence of surface roughness on the cross-flow around a circular cylinder, Journal of Fluid Mechanics, Vol. 46(2), 1970, 321-335.

[7] N akamura Y., Tomonari Y., The effects of surface roughness on the flow past circular cylinder at high Reynolds numbers, Journal of Fluid Mechanics, Vol. 123, 1981, 363-378.

[8] K leissl K., Georgakis C.T., Comparison of the aerodynamics of bridge cables with helical fillets and a pattern-indented surface, Journal of Wind Engineering and Industrial Aerodynamics, Vol. 104-106, 2012, 166-175.