Coherent motions in windbreak flow

Experimental data on windbreak flows have been analysed, using several statistical methods. Our analysis demonstrates that coherent structures exist in the mixing region of a porous windbreak (50% porosity) flow, and are largely responsible for the momentum transport that re-accelerates the leeward flow. A comparison between windbreak flow and laboratory turbulent mixing layers suggests that the dominant structures in these two flows are similar. Some previous numerical and experimental results are interpreted in light of the coherent structures and the self-similar property in the mixing region of a windbreak flow.