### Fluid dynamics and Bernoulli's equation

Aug 5, This means you had 10 g/s mass flow rate this time. So, say your domestic water mains pressure is usually kPa gauge and you take 5 minutes to fill a bath. Nov 10, For turbulent flow, the speed and or the direction of the flow varies. mass flows past a given point, so it's the total mass flowing past divided by the time interval. non-viscous, incompressible fluid are related by the equation: To figure out how fast the water is moving when it comes out of the ground, we. Jun 22, Relationship Between Pressure Drop and Flow Rate in a Pipeline . evaluating just the change in elevation, consider 60 °F water flowing up a.

Pressure Change due to Velocity Change Fluid velocity will change if the internal flow area changes.

For example, if the pipe size is reduced, the velocity will increase and act to decrease the static pressure. If the flow area increases through an expansion or diffuser, the velocity will decrease and result in an increase in the static pressure.

If the pipe diameter is constant, the velocity will be constant and there will be no change in pressure due to a change in velocity. As an example, if an expansion fitting increases a 4 inch schedule 40 pipe to a 6 inch schedule 40 pipe, the inside diameter increases from 4.

If the flow rate through the expansion is gpm, the velocity goes from 9. The change in static pressure across the expansion due to the change in velocity is: In other words, pressure has increased by almost 0. Pressure Change due to Head Loss Since head loss is a reduction in the total energy of the fluid, it represents a reduction in the capability of the fluid to do work.

### What is volume flow rate? (article) | Fluids | Khan Academy

Head loss does not reduce the fluid velocity consider a constant diameter pipe with a constant mass flow rateand it will not be effect the elevation head of the fluid consider a horizontal pipe with no elevation change from inlet to outlet. Therefore, head loss will always act to reduce the pressure head, or static pressure, of the fluid. There are several ways to calculate the amount of energy lost due to fluid flow through a pipe.

Turbulence is a factor in most real-world applications. The Hagen-Poiseuille Law The French physicist Jean Leonard Marie Poiseuille conducted a series of experiments on fluid flow during the early 19th century and published his findings in Poiseuille is credited with having deduced that flow rate was proportional to the fourth power of pipe radius, but a German hydraulics engineer, Gotthilf Hagen, had already arrived at the same results.

For this reason, physicists sometimes refer to the relationship Poiseuille published as the Hagen-Poiseuille law.

## What is volume flow rate?

The law is expressed as: At a given temperature, flow rate through a tube or pipe is inversely proportional to the length of the tube the viscosity of the liquid. Flow rate is directly proportional to the pressure gradient and the fourth power of the radius of the pipe.

Applying Poiseuille's Law Even when turbulence is a factor, you can still use Poiseuille's equation to get a reasonably accurate idea of the how flow rate changes with pipe diameter.

Keep in mind that the stated size of a pipe is a measure of its diameter, and you need the radius to apply Poiseuille's law.

The radius is half the diameter.