- Title
- A note on the velocity derivative flatness factor in decaying HIT
- Creator
- Djenidi, L.; Danaila, L.; Antonia, R. A.; Tang, S.
- Relation
- Physics of Fluids Vol. 29, Issue 5, no. 51702
- Publisher Link
- http://dx.doi.org/10.1063/1.4983724
- Publisher
- AIP Publishing
- Resource Type
- journal article
- Date
- 2017
- Description
- We develop an analytical expression for the velocity derivative flatness factor, F, in decaying homogenous and isotropic turbulence (HIT) starting with the transport equation of the third-order moment of the velocity increment and assuming self-preservation. This expression, fully consistent with the Navier-Stokes equations, relates F to the product between the second-order pressure derivative (ꝺ2p=ꝺx²) and second-order moment of the longitudinal velocity derivative ((ꝺu=ꝺx)²), highlighting the role the pressure plays in the scaling of the fourth-order moment of the longitudinal velocity derivative. It is also shown that F has an upper bound which follows the integral of k*⁴Ep*(k*) where Ep and k are the pressure spectrum and the wavenumber, respectively (the symbol * represents the Kolmogorov normalization). Direct numerical simulations of forced HIT suggest that this integral converges toward a constant as the Reynolds number increases.
- Subject
- homogenous and isotropic turbulence; Navier Stokes equations; K62; Kolmogorov; Reymolds numbers
- Identifier
- http://hdl.handle.net/1959.13/1399069
- Identifier
- uon:34526
- Identifier
- ISSN:1070-6631
- Rights
- The following article appeared in Physics of Fluids 2017 29:5 and may be found at https://doi.org/10.1063/1.4983724. This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing.
- Language
- eng
- Full Text
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