 measur two-dimension three-dimension rough element boundari layer transit measur two-dimension three-dimension rough element boundari layer transit studi rough transit dryden basi data two-dimension rough element trip wire repres reason well term function relat reynold number transit base distanc lead edg height rough element boundari-layer displac thick posit element suggest addit data extend rang higher valu cours investig transit flat plate conduct nation bureau standard two- dimension rough element appear desir row three-dimension rough element behav 