Large Eddy Simulations of Rough Turbulent Channel Flows Bounded by Irregular Roughness: Advances Toward a Universal Roughness Correlation
| Autor: | Domenico Saccone, Enrico Napoli, Mauro De Marchis, Barbara Milici |
|---|---|
| Přispěvatelé: | M. De Marchis, D. Saccone, B. Milici, E. Napoli |
| Rok vydání: | 2020 |
| Předmět: |
Friction
Logarithm General Chemical Engineering Geometry General Physics and Astronomy Turbulent channel flows Large eddy simulation 02 engineering and technology Surface finish Macroscopic effects 01 natural sciences Reynolds number Settore ICAR/01 - Idraulica 010305 fluids & plasmas Root mean square symbols.namesake Sinusoidal functions 0203 mechanical engineering 0103 physical sciences Physical and Theoretical Chemistry Channel flow Effective slope Physics Roughness correlation Turbulence Mathematical analysis Textures Mean velocity profiles Roughness Open-channel flow Wall flow Geometrical property 020303 mechanical engineering & transports Amplitude LES Logarithmic regions Mean absolute deviations symbols Large eddy simulation |
| Zdroj: | Flow, Turbulence and Combustion. 105:627-648 |
| ISSN: | 1573-1987 1386-6184 |
| DOI: | 10.1007/s10494-020-00167-5 |
| Popis: | The downward shift of the mean velocity profile in the logarithmic region, known as roughness function, $$\Delta U^+$$ , is the major macroscopic effect of roughness in wall bounded flows. This speed decrease, which is strictly linked to the friction Reynolds number and the geometrical properties which define the roughness pattern such as roughness height, density, shape parameters, has been deeply investigated in the past decades. Among the geometrical parameters, the effective slope (ES) seems to be suitable to estimate the roughness function at fixed friction Reynolds number, Re $$_{\tau }$$ . In the present work, the effects of several geometrical parameters on the roughness function, in both transitional and fully rough regimes, are investigated by means of large eddy simulation of channel flows characterized by different wall-roughness textures at different values of Re $$_{\tau }$$ up to 1000. The roughness geometry is generated by the superimposition of sinusoidal functions with random amplitudes and it is exactly resolved in the simulations. A total number of 10 cases are solved. With the aim to find a universal correlation between the roughness geometry and the induced roughness function, we analyzed the effect of more than a single geometrical parameter, including the effective slope, which takes into account both the roughness height and its texture. Based on data obtained from our simulations and a number of data points from the literature, a correlation between the ES and the root mean square of the roughness oscillation, as well as between ES and the mean absolute deviation of the roughness, satisfactorily predicts the roughness function. |
| Databáze: | OpenAIRE |
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