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RESEARCH PRODUCT

Large eddy simulations on the effect of the irregular roughness shape on turbulent channel flows

M. De MarchisBarbara MiliciEnrico Napoli

subject

Higher order statisticMaterials scienceTurbulence simulationTurbulent channel flows Large eddy simulation02 engineering and technologyReynolds stressSurface finish01 natural sciencesReynolds numberSettore ICAR/01 - Idraulica010305 fluids & plasmasPhysics::Fluid Dynamicssymbols.namesake0203 mechanical engineering0103 physical sciencesMean flowReynolds equationAnisotropyChannel flowFluid Flow and Transfer ProcessesTurbulenceMean velocity profileMechanical EngineeringIrregular roughneReynolds numberSinusoidal functionMechanicsCondensed Matter PhysicsOpen-channel flowShear stre020303 mechanical engineering & transportsAmplitudeReynolds streTurbulence Irregular shapeTurbulence intensityLESsymbolsTurbulence modulation

description

Abstract Large Eddy Simulations (LES) are carried out to investigate on the mean flow in turbulent channel flows over irregular rough surfaces. Here the attention is focused to selectively investigate on the effect induced by crests or cavities of the roughness. The irregular shape is generated through the super-imposition of sinusoidal functions having random amplitude and four different wave-lengths. The irregular roughness profile is reproduced along the spanwise direction in order to obtain a 2D rough shape. The analysis of the mean velocity profiles shows that roughness crests induce higher effect in the outer-region whereas roughness cavities cause the highest effects in the inner-region with a reduced effect in the external region. The numerical simulations have been carried out at friction Reynolds number Reτ=395. Similar results have been found for the higher order statistics: turbulence intensities or shear stresses. The analysis of the Reynolds stress anisotropy tensor confirms the existence of specific roles of cavities and crests in the turbulence modulation.

yearjournalcountryeditionlanguage
2019-12-01International Journal of Heat and Fluid Flow
https://doi.org/10.1016/j.ijheatfluidflow.2019.108494