A note on the velocity derivative flatness factor in decaying HIT

作者：Djenidi, L.^*; Danaila, L.; Antonia, R. A.; Tang, S.

来源：Physics of Fluids, 2017, 29(5): 051702.

DOI：10.1063/1.4983724

• REYNOLDS-NUMBER DEPENDENCE
• ENERGY-DISSIPATION RATE
• TRANSPORT-EQUATION
• TURBULENT FLOWS
• LOCAL-STRUCTURE
• PRESSURE
• FLUID

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 (partial derivative(2)p/partial derivative x(2)) and second-order moment of the longitudinal velocity derivative ((partial derivative u/partial derivative x)(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*E-4(p)*(k*) where E-p 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. Published by AIP Publishing.

• 出版日期2017-5
• 单位哈尔滨工业大学深圳研究生院