 relat wall temperatur rough boundari layer transit relat wall temperatur rough boundari layer transit experiment demonstr rise subsequ fall transit reynold number decreas wall- to-ambient temperatur ratio subject note case argu increas effect rough wall cool suffici explain transit-revers phenomenon nomin smooth bodi case criterion transit revers valu low eter reynold number form veloc kinemat viscos base calcul condit height rough element undisturb laminar boundari layer station rough locat note submit method evalu rough transit lead opposit conclus 