Resolvent analysis predictions of energy transfer in turbulent channel flow

Symon, S., Illingworth, S. J. and Marusic, I. (2020) Resolvent analysis predictions of energy transfer in turbulent channel flow. Chanson, Hubert and Brown, Richard (eds.) In 22nd Australasian Fluid Mechanics Conference, AFMC 2020. Australasian Fluid Mechanics Society.. (doi:10.14264/05a39db).

Abstract

We analyse the inter-scale transfer of energy for turbulent channel flow at Re_τ = 180 in a minimal flow unit. The dominant energy-producing modes are streamwise-constant streaks with a spanwise spacing of approximately 100 wall units. Since the viscous dissipation for these scales is not sufficient to balance production, the nonlinear terms redistribute the excess energy to other scales. We compare the energy balance to predictions from resolvent analysis and show that it does not model energy transfer well. Nevertheless, we find that the energy transferred from the streamwise-constant streaks can be predicted reasonably well by a Cess eddy viscosity profile. As such, eddy viscosity is an effective model for the nonlinear terms in resolvent analysis and explains good predictions for the most energetic streamwise-constant streaks. Eddy viscosity does not respect the conservative nature of nonlinear transfer and is less effective for scales which receive energy from the nonlinear terms.

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