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|Title:||Quadruple decomposition of current-dominated pulsatile rough-wall turbulent pipe flow|
|Citation:||21st Australasian Fluid Mechanics Conference, 2018 / Lau, T., Kelso, R. (ed./s), pp.1-4|
|Publisher:||Australasian Fluid Mechanics Society|
|Conference Name:||Australasian Fluid Mechanics Conference (10 Dec 2018 - 13 Dec 2018 : Adelaide, Australia)|
|T. O. Jelly, R. C. Chin, S. J. Illingworth, J. P. Monty, L. Marusic and A. S. H. Ooi|
|Abstract:||The physics of pulsatile rough-wall turbulent pipe flow is investigated using data from direct numerical simulation (DNS). Three geometrically-scaled sinusoidal roughness topographies are considered — the amplitude and wavelength of each surface are systematically varied whilst holding their amplitude-towavelength ratio constant. Pulsation is achieved by imposing a time-harmonic axial pressure gradient. The resulting flow-field is triple phase-averaged (in two spatial directions and also in time) which permits a quadruple decomposition of the instantaneous field variables to be invoked. The four components of the quadruple decomposition are: (i) a global-averaged mean component; (ii) a steady roughness-induced fluctuation; (iii) an unsteady pulsation-induced fluctuation and (iv) the remaining turbulent fluctuation. We compare statistics of (i)-(iv) against their non-pulsatile counterpart using past results from related work [1, 2]. Whilst the pulsatile and non-pulsatile data collapse well in the outer region, clear differences are observed in the near-roughness region. In particular, profiles of the mean axial velocity, roughness-induced stress and turbulence-induced stress exhibit consistently lower magnitudes below the roughness crests under pulsatile conditions.|
|Rights:||Commencing with 19AFMC, the Society holds copyright to papers which appear in the Proceedings. Prior to that, copyright resides with authors of the papers.|
|Appears in Collections:||Mechanical Engineering conference papers|
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