 viscou effect pitot tube low speed viscou effect pitot tube low speed measur pressur blunt-nose pitot tube air stream reynold number 15 1000 express term pressur coeffici densiti fluid static pressur veloc undisturb stream previou investig greater 1 low reynold number increas reynold number 50 base extern tube radiu disagr work hurd cheski shapiro decreas 1 reynold number valu experi plot reynold number base intern tube radiu curv closer agreement extern radiu 