I have been running this question through my mind.
If you apply pressure to a fluid (with say a piston) through a straight hole then the faster you push it through with applied pressure then the more back pressure it builds. Until eventually it pretty much locks up.
I understand that.
Ok if you push fluid through a tapered hole then the fluid velocity should increase and pressure should decrease.
My question is will the resistance to applied pressure stay consistent, decrease, or increase with increased applied speed of the piston?