A note on the amplitude modulation phenomenon in non-canonical wall-bounded flows
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| Format: | Preprint |
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2024
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| author | Lozier, Mitchell Marusic, Ivan Deshpande, Rahul |
| author_facet | Lozier, Mitchell Marusic, Ivan Deshpande, Rahul |
| contents | The amplitude modulation phenomena, defined originally by Mathis et al. (J. Fluid Mech., 628, 311-337; 2009), corresponds to a unique non-linear interaction between Reynolds number ($Re_τ$) dependent large-scale motions and $Re_τ$-invariant inner-scale motions observed in canonical wall-bounded flows. While similar non-linear interactions have been quantified previously in non-canonical wall-bounded flows, linking them solely to amplitude modulation is questionable due to the fact that each non-canonical effect is associated with distinct variations in the energies of both the large and inner scaled motions. This study revisits analysis of non-linear triadic interactions, with consideration to various non-canonical effects, by analyzing published hot-wire datasets acquired in the large Melbourne wind tunnel. It is found that triadic interactions, across the entire turbulence scale hierarchy, may become statistically significant with increasing intensity of non-canonical effects such as wall roughness, pressure gradients, and spanwise or wall-normal forcing (when compared relative to their respective canonical baseline cases at matched $Re_τ$). This stands in contrast to previous observations made in canonical flows, where only the interaction between inner scales and inertia-dominated large scales was considered dynamically significant for increasing $Re_τ$. The implications of these findings are discussed for near-wall flow prediction models in non-canonical flows, which should take into account \emph{all} non-linear interactions coexisting in wall-bounded flows. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2409_00154 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | A note on the amplitude modulation phenomenon in non-canonical wall-bounded flows Lozier, Mitchell Marusic, Ivan Deshpande, Rahul Fluid Dynamics The amplitude modulation phenomena, defined originally by Mathis et al. (J. Fluid Mech., 628, 311-337; 2009), corresponds to a unique non-linear interaction between Reynolds number ($Re_τ$) dependent large-scale motions and $Re_τ$-invariant inner-scale motions observed in canonical wall-bounded flows. While similar non-linear interactions have been quantified previously in non-canonical wall-bounded flows, linking them solely to amplitude modulation is questionable due to the fact that each non-canonical effect is associated with distinct variations in the energies of both the large and inner scaled motions. This study revisits analysis of non-linear triadic interactions, with consideration to various non-canonical effects, by analyzing published hot-wire datasets acquired in the large Melbourne wind tunnel. It is found that triadic interactions, across the entire turbulence scale hierarchy, may become statistically significant with increasing intensity of non-canonical effects such as wall roughness, pressure gradients, and spanwise or wall-normal forcing (when compared relative to their respective canonical baseline cases at matched $Re_τ$). This stands in contrast to previous observations made in canonical flows, where only the interaction between inner scales and inertia-dominated large scales was considered dynamically significant for increasing $Re_τ$. The implications of these findings are discussed for near-wall flow prediction models in non-canonical flows, which should take into account \emph{all} non-linear interactions coexisting in wall-bounded flows. |
| title | A note on the amplitude modulation phenomenon in non-canonical wall-bounded flows |
| topic | Fluid Dynamics |
| url | https://arxiv.org/abs/2409.00154 |