Fluctuations of energy injection rate in a shear flow

We study the instantaneous and local energy injection in a turbulent shear flow driven by volume forces. The energy injection can be both positive and negative. Extremal events are related to coherent streaks. The probability distribution is asymmetric, deviates slightly from a Gaussian shape and depends on the position in shear direction. The probabilities for positive and negative injection are exponentially related, but the prefactor in the exponent varies across the shear layer.