- #1
fog37
- 1,568
- 108
Hello everyone,
I understand the hydrostatic fluid pressure in static fluids: static pressure varies linearly with depth and the infinitesimal fluid parcels located at the same depth in the fluid experience the same isotropic hydrostatic pressure. By Pascal principle, the atmospheric pressure at the liquid's free surface must added to the hydrostatic pressure.
Let's now consider a liquid flowing with speed v inside a horizontal pipe of diameter D with piezometers (small vertical tubes open to the atmosphere) connected to the pipe. The height reached by the fluid inside the piezometric tubes correlates with the pressure at the base of the tubes. But what pressure does the height indicate? Does it indicate the total pressure, the static pressure or the dynamic pressure? I know that, physically, there is only one type of pressure but it is sometimes convenient to separate it in different contributions.
Since the piezometric tubes are vertical (perpendicular to the flow direction), I think the height reached by the fluid inside the piezometric tubes only indirectly measures the static pressure without the kinetic pressure contribution coming from the fluid motion. Is that correct? If that is the case, would this measured static pressure be the same as the pressure the fluid was not moving inside the pipe?
To measure the total pressure we would need to a stagnation point where the moving fluid impacts and exerts the total pressure...
Thanks!
Fog37
I understand the hydrostatic fluid pressure in static fluids: static pressure varies linearly with depth and the infinitesimal fluid parcels located at the same depth in the fluid experience the same isotropic hydrostatic pressure. By Pascal principle, the atmospheric pressure at the liquid's free surface must added to the hydrostatic pressure.
Let's now consider a liquid flowing with speed v inside a horizontal pipe of diameter D with piezometers (small vertical tubes open to the atmosphere) connected to the pipe. The height reached by the fluid inside the piezometric tubes correlates with the pressure at the base of the tubes. But what pressure does the height indicate? Does it indicate the total pressure, the static pressure or the dynamic pressure? I know that, physically, there is only one type of pressure but it is sometimes convenient to separate it in different contributions.
Since the piezometric tubes are vertical (perpendicular to the flow direction), I think the height reached by the fluid inside the piezometric tubes only indirectly measures the static pressure without the kinetic pressure contribution coming from the fluid motion. Is that correct? If that is the case, would this measured static pressure be the same as the pressure the fluid was not moving inside the pipe?
To measure the total pressure we would need to a stagnation point where the moving fluid impacts and exerts the total pressure...
Thanks!
Fog37