### Abstract

Original language | English |
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Article number | 045103 |

Number of pages | 14 |

Journal | Physics of Fluids |

Volume | 30 |

Early online date | 4 Apr 2018 |

DOIs | |

Publication status | Published - Apr 2018 |

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*Physics of Fluids*,

*30*, [045103]. https://doi.org/10.1063/1.5018346

**Statistical features of rapidly rotating decaying turbulence: Enstrophy and energy spectra and coherent structures.** / Sharma, Manohar K.; Kumar, Abhishek; Verma, Mahendra K.; Chakraborty, Sagar.

Research output: Contribution to journal › Article

*Physics of Fluids*, vol. 30, 045103. https://doi.org/10.1063/1.5018346

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TY - JOUR

T1 - Statistical features of rapidly rotating decaying turbulence: Enstrophy and energy spectra and coherent structures

AU - Sharma, Manohar K.

AU - Kumar, Abhishek

AU - Verma, Mahendra K.

AU - Chakraborty, Sagar

PY - 2018/4

Y1 - 2018/4

N2 - In this paper, we investigate the properties of rapidly rotating decaying turbulence using numerical simulations and phenomenological modeling. We find that as the turbulent flow evolves in time, the Rossby number decreases to ∼10−3, and the flow becomes quasi-two-dimensional with strong coherent columnar structures arising due to the inverse cascade of energy. We establish that a major fraction of energy is confined in Fourier modes (±1, 0, 0) and (0, ±1, 0) that correspond to the largest columnar structure in the flow. For wavenumbers (k) greater than the enstrophy dissipation wavenumber (kd), our phenomenological arguments and numerical study show that the enstrophy flux and spectrum of a horizontal cross section perpendicular to the axis of rotation are given by ϵωexp(−C(k/kd)2) and Cϵ2/3ωk−1exp(−C(k/kd)2), respectively; for this 2D flow, ϵω is the enstrophy dissipation rate, and C is a constant. Using these results, we propose a new form for the energy spectrum of rapidly rotating decaying turbulence: E(k)=Cϵ2/3ωk−3exp(−C(k/kd)2). This model of the energy spectrum is based on wavenumber-dependent enstrophy flux, and it deviates significantly from power law energy spectrum reported earlier.

AB - In this paper, we investigate the properties of rapidly rotating decaying turbulence using numerical simulations and phenomenological modeling. We find that as the turbulent flow evolves in time, the Rossby number decreases to ∼10−3, and the flow becomes quasi-two-dimensional with strong coherent columnar structures arising due to the inverse cascade of energy. We establish that a major fraction of energy is confined in Fourier modes (±1, 0, 0) and (0, ±1, 0) that correspond to the largest columnar structure in the flow. For wavenumbers (k) greater than the enstrophy dissipation wavenumber (kd), our phenomenological arguments and numerical study show that the enstrophy flux and spectrum of a horizontal cross section perpendicular to the axis of rotation are given by ϵωexp(−C(k/kd)2) and Cϵ2/3ωk−1exp(−C(k/kd)2), respectively; for this 2D flow, ϵω is the enstrophy dissipation rate, and C is a constant. Using these results, we propose a new form for the energy spectrum of rapidly rotating decaying turbulence: E(k)=Cϵ2/3ωk−3exp(−C(k/kd)2). This model of the energy spectrum is based on wavenumber-dependent enstrophy flux, and it deviates significantly from power law energy spectrum reported earlier.

U2 - 10.1063/1.5018346

DO - 10.1063/1.5018346

M3 - Article

VL - 30

JO - Physics of Fluid

JF - Physics of Fluid

SN - 1070-6631

M1 - 045103

ER -