Hello
as we know according to the Bernoulli equation that the presser increase when the velocity decrease so when I test in water gems I use for that reason two-pipe with different diameter to show pressure change according to velocity but what I notice is that the velocity change but pressure still constant on junction any explanation?
Here is more information on considering velocity head in WaterGEMS, as a reference.
How is velocity head handled in WaterGEMS, WaterCAD, and HAMMER?
Regards,
Sushma Choure
Bentley Technical Suppport
Answer Verified By: mohamad joun
okay thank you that was very helpful and yes the effect of a velocity change on pressure is negligible in most cases
Water distribution models calculate the hydraulic grade, not the energy grade. In most cases the difference is negligible.
Hydraulic grade is calculate at nodes not along links. The velocity may not be unique at a node.
ok thank you for your help yes I put the (C) coefficient very high to make study only for pressure and velocity
but why pressure is controlled by head loss in pipes and the Bernoulli equation is not applied?
in other meaning in reality, when I want to measure the pressure with (pressure gauge) at junction 1 the number that I will get will be the same as shown in software or as Bernoulli equation calculation?
In water distribution piping, the pressure is controlled by head loss in pipes. You have such low velocities that head loss is very small in your example. The velocity head is very small at nodes and if you have junctions that are crosses and tees, which of the velocities do you use?