# Fluid Velocity and flow rate questions

• Creaton1
In summary: You will need to use the Bernoulli equation in conjunction with the continuity equation to find the ideal flow. Then use the value and definition of discharge coefficient to find the real flow. You can also find h in terms of mercury (depending on what the examiner wants) using the density relation I applied.
Creaton1
I am going over a past paper and this is my last question I am stuck on. Once I can solve this I can finally progress. This is from a past paper and my exam will be on a variation of the question.

Can someone please talk me through the questions, displaying the method, calculations and equations needed to answer each part.

http://postimage.org/image/33j1ag9fo/ - Question and Diagram.

I have to determine:

- Velocity of petrol through the pipe
- Mass Flow of petrol
- Manometer reading if the flow rate were reduced by 50%

I know v1*p1 = v2*p2 = const,

Regards,

Will

You will need to use the Bernoulli equation in conjunction with the continuity equation to find the ideal flow. Then use the value and definition of discharge coefficient to find the real flow.

How do I figure out velocity? p1 - p2? how do i work that out?

OK, I will give you some hints.

First, write the Bernoulli Equation:

P1 + p v1^2 / 2 = P2 + p v2^2 / 2

And you are trying to find v1, the velocity in the pipe. Then use the continuity equation v1* A1 = v2 * A2 and solve for v2 = v1 * A1 / A2.

Plug this expression for v2 into the Bernoulli equation and solve for v1. Everything is given to do this !

Work on it - let me know if you need any help. This is one of the most basic and practical fluid dynamics solutions there is.

P.S.

You can figure P1 - P2 from the difference in column levels in the manometer (called the manometer "deflection").

Hi I just registered on this site, I recently received my BSc in Mechanical engineering so I thought I'd take a quick try at it, sorry about the handwriting-bare with me. ANYONE PLEASE CORRECT ME IF I'VE GONE WRONG SOMEWHERE.
http://postimage.org/image/8fq8490-
for the last part c), the initial value of the flow rate from b) is halved.This means the velocities will also change. Find V1 using Q(m3/s) or m (kg/s), then work backwards from V1= 2gh/((m^2)-1) to find h in terms of petrol. You can also find h in terms of mercury (depending on what the examiner wants) using the density relation I applied(it's actually a pressure relation,but the Rho's on both sides cancel out) .
I hope this helps,
William

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## What is fluid velocity?

Fluid velocity is the measure of how fast a fluid (such as water or air) is moving. It is typically measured in units of distance per unit time, such as meters per second or feet per minute.

## What factors affect fluid velocity?

The factors that affect fluid velocity include the type of fluid, its density and viscosity, the size of the container or channel it is flowing through, and the pressure and temperature of the fluid.

## How is fluid velocity calculated?

Fluid velocity can be calculated by dividing the flow rate (volume of fluid passing through a given point in a given amount of time) by the cross-sectional area of the fluid flow. It can also be calculated using Bernoulli's equation, which takes into account the fluid's kinetic energy, potential energy, and pressure.

## What is flow rate?

Flow rate is the measure of how much fluid is passing through a given point in a given amount of time. It is typically measured in units of volume per unit time, such as liters per second or cubic feet per minute.

## How do you measure flow rate?

Flow rate can be measured using various instruments such as flow meters, pitot tubes, orifice plates, and flow sensors. These instruments measure the velocity of the fluid and use it to calculate the flow rate.

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