"flows at Reynolds numbers larger than 5000 are typically (but not necessarily) turbulent, while those at low Reynolds numbers usually remain laminar. In pipe flow, for example, turbulence can first be sustained if the Reynolds number is larger than a critical value of about 2040; moreover, the turbulence is generally interspersed with laminar flow until a larger Reynolds number of about 3000. In turbulent flow, unsteady vortices appear on many scales and interact with each other. Drag due to boundary layer skin friction increases. The structure and location of boundary layer separation often changes, sometimes resulting in a reduction of overall drag"
When I use a tap, the flow is often quite turbulent. The stream looks twisted and if you put your hand in it then water rebounds all over the place. But sometimes I will quickly flick where the water comes out of the tap and the flow will become less turbulent. Put my hand in it and it becomes smooth. The same effect as those grills over some tap outlets except the flow is not filtered as a grill would do. It looks fine.
The grill and the hand "effect" is two different things. the grill cuts the turbulence up. i think.
open up the valve so it flows very little. you will still hear the turbulence but its only in the valve.
when you slam the valve open you probably avoid the turbulence in the valve to go with you. avoiding it to escalade.
your tap is probably in the transient area between the reynolds number 2040 and 3000.
All you need to know is that you probably can`t do this on the exhaust of a F1 car. The air/gases involved gets turbulent too easy. Too high a Reynolds number probably.
Slight OT: "The structure and location of boundary layer separation often changes, sometimes resulting in a reduction of overall drag"
this can be used with benefit when porting engines, if i read what i think i read. Smooth polished ports are not neccesarily the best flowing. (that i have heard before)
Edited by MatsNorway, 27 November 2011 - 10:54.