Spatial Variation of Scaling Exponents for Structure Functions in a Decaying Turbulence

摘要

Streamwise evolution of velocity structure functions in a decaying homogeneous and nearly isotropic turbulence is reported for Reynolds number up to Reλ ≈ 720.Both direct method and extended self similarity method were used to measure the scaling exponents.It is found that relative scaling exponents by direct method are in good agreement to those calculated by ESS method.Furthermore,transverse scaling exponents are obviously smaller than the longitudinal ones,which indicate larger intermittency of transverse velocity components than longitudinal ones.Finally,obvious trend is observed for the ratio between longitudinal and transverse structure functions in the inertial sub-range,and the values at last locations are closer to theoretical expectations.