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Hosseini, Seyed M.
Publications (2 of 2) Show all publications
Vinuesa, R., Hosseini, S. M., Hanifi, A., Henningson, D. S. & Schlatter, P. (2017). Pressure-gradient turbulent boundary layers developing around a wing section. Flow Turbulence and Combustion, 99(3-4), 613-641
Open this publication in new window or tab >>Pressure-gradient turbulent boundary layers developing around a wing section
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2017 (English)In: Flow Turbulence and Combustion, ISSN 1386-6184, E-ISSN 1573-1987, Vol. 99, no 3-4, p. 613-641Article in journal (Refereed) Published
Abstract [en]

A direct numerical simulation database of the flow around a NACA4412 wing section at R e (c) = 400,000 and 5(ay) angle of attack (Hosseini et al. Int. J. Heat Fluid Flow 61, 117-128, 2016), obtained with the spectral-element code Nek5000, is analyzed. The Clauser pressure-gradient parameter beta ranges from ae integral 0 and 85 on the suction side, and from 0 to - 0.25 on the pressure side of the wing. The maximum R e (oee integral) and R e (tau) values are around 2,800 and 373 on the suction side, respectively, whereas on the pressure side these values are 818 and 346. Comparisons between the suction side with zero-pressure-gradient turbulent boundary layer data show larger values of the shape factor and a lower skin friction, both connected with the fact that the adverse pressure gradient present on the suction side of the wing increases the wall-normal convection. The adverse-pressure-gradient boundary layer also exhibits a more prominent wake region, the development of an outer peak in the Reynolds-stress tensor components, and increased production and dissipation across the boundary layer. All these effects are connected with the fact that the large-scale motions of the flow become relatively more intense due to the adverse pressure gradient, as apparent from spanwise premultiplied power-spectral density maps. The emergence of an outer spectral peak is observed at beta values of around 4 for lambda (z) ae integral 0.65 delta (99), closer to the wall than the spectral outer peak observed in zero-pressure-gradient turbulent boundary layers at higher R e (oee integral) . The effect of the slight favorable pressure gradient present on the pressure side of the wing is opposite the one of the adverse pressure gradient, leading to less energetic outer-layer structures.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Turbulent boundary layer, Pressure gradient, Wing section, Direct numerical simulation
National Category
Fluid Mechanics and Acoustics
Identifiers
urn:nbn:se:kth:diva-220718 (URN)10.1007/s10494-017-9840-z (DOI)000416838200005 ()2-s2.0-85027373953 (Scopus ID)
Funder
Swedish Research CouncilKnut and Alice Wallenberg FoundationSwedish e‐Science Research Center
Note

QC 20180104

Available from: 2018-01-03 Created: 2018-01-03 Last updated: 2018-01-04Bibliographically approved
Hosseini, S. M., Vinuesa, R., Schlatter, P., Hanifi, A. & Henningson, D. (2016). Direct numerical simulation of the flow around a wing section at moderate Reynolds number. International Journal of Heat and Fluid Flow, 61, 117-128
Open this publication in new window or tab >>Direct numerical simulation of the flow around a wing section at moderate Reynolds number
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2016 (English)In: International Journal of Heat and Fluid Flow, ISSN 0142-727X, E-ISSN 1879-2278, Vol. 61, p. 117-128Article in journal (Other academic) Published
Abstract [en]

Abstract A three-dimensional direct numerical simulation has been performed to study the turbulent flow around the asymmetric NACA4412 wing section at a moderate chord Reynolds number of R e c = 400 , 000 , with an angle of attack of A o A = 5 ∘ . The mesh was optimized to properly resolve all relevant scales in the flow, and comprises around 3.2 billion grid points. The incompressible spectral-element Navier–Stokes solver Nek5000 was used to carry out the simulation. An unsteady volume force is used to trip the flow to turbulence on both sides of the wing at 10% of the chord. Full turbulence statistics are computed in addition to collection of time history data in selected regions. The Reynolds numbers on the suction side reach Reτ ≃ 373 and R e Ξ = 2 , 800 with the pressure-gradient parameter ranging from β ≈ 0.0 to β ≈ 85. Similarly, on the pressure side, the Reynolds numbers reach Reτ ≈ 346 and R e Ξ = 818 while β changes from β ≈ 0.0 to β ≈ − 0.25 . The effect of adverse pressure gradients on the mean flow is consistent with previous observations, namely a steeper incipient log law, a more prominent wake region and a lower friction. The turbulence kinetic energy profiles show a progressively larger inner peak for increasing pressure gradient, as well as the emergence and development of an outer peak with stronger APGs. The present simulation shows the potential of high-order (spectral) methods in simulating complex external flows at moderately high Reynolds numbers.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Turbulent boundary layer, Vortex shedding, Wake, Incipient separation, Pressure gradient, NACA4412
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-177610 (URN)10.1016/j.ijheatfluidflow.2016.02.001 (DOI)000390745800013 ()
Note

QC 20181205

Available from: 2015-11-24 Created: 2015-11-24 Last updated: 2018-12-05Bibliographically approved
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