The modification of the turbulent cascade by polymeric additives is addressed by direct numerical simulations of homogeneous isotropic turbulence of a FENE-P fluid. According to the appropriate form of the Ka?rma?n-Howarth equation, two kinds of energy fluxes exist, namely the classical transfer term and the coupling with the polymers. Depending on the Deborah number, the response of the flow may result either in a pure damping or in the depletion of the small scales accompanied by increased fluctuations at large scale. The latter behaviour corresponds to an overall reduction of the dissipation rate with respect to an equivalent Newtonian flow with identical fluctuation intensity. The relevance of the position of the crossover scale between the two components of the energy flux with respect to the Taylor microscale of the system is discussed.

Homogenous isotropic turbulence in dilute polymers / De Angelis E.; Casciola C.M.; Benzi R.; Piva R.. - In: JOURNAL OF FLUID MECHANICS. - ISSN 0022-1120. - STAMPA. - 531:(2005), pp. 1-10. [10.1017/S0022112005003666]

Homogenous isotropic turbulence in dilute polymers

DE ANGELIS, ELISABETTA;
2005

Abstract

The modification of the turbulent cascade by polymeric additives is addressed by direct numerical simulations of homogeneous isotropic turbulence of a FENE-P fluid. According to the appropriate form of the Ka?rma?n-Howarth equation, two kinds of energy fluxes exist, namely the classical transfer term and the coupling with the polymers. Depending on the Deborah number, the response of the flow may result either in a pure damping or in the depletion of the small scales accompanied by increased fluctuations at large scale. The latter behaviour corresponds to an overall reduction of the dissipation rate with respect to an equivalent Newtonian flow with identical fluctuation intensity. The relevance of the position of the crossover scale between the two components of the energy flux with respect to the Taylor microscale of the system is discussed.
2005
Homogenous isotropic turbulence in dilute polymers / De Angelis E.; Casciola C.M.; Benzi R.; Piva R.. - In: JOURNAL OF FLUID MECHANICS. - ISSN 0022-1120. - STAMPA. - 531:(2005), pp. 1-10. [10.1017/S0022112005003666]
De Angelis E.; Casciola C.M.; Benzi R.; Piva R.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11585/31957
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