What is Volume flow rate: Definition and 29 Discussions

In physics and engineering, in particular fluid dynamics, the volumetric flow rate (also known as volume flow rate, rate of fluid flow, or volume velocity) is the volume of fluid which passes per unit time; usually it is represented by the symbol Q (sometimes V̇). The SI unit is cubic metres per second (m3/s). Another unit used is standard cubic centimetres per minute (SCCM).
In hydrometry, it is known as discharge.
In US customary units and imperial units, volumetric flow rate is often expressed as cubic feet per second (ft3/s) or gallons per minute (either US or imperial definitions).
Volumetric flow rate should not be confused with volumetric flux, as defined by Darcy's law and represented by the symbol q, with units of m3/(m2·s), that is, m·s−1. The integration of a flux over an area gives the volumetric flow rate.

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  1. Ophi-Siren-Kit

    Speed/Velocity and Volume Flow Rate of Viscous Fluids

    In my first attempt, I started off converting the radii of all three sections from centimeters (10, 8, 6) to meters (0.10 , 0.08 , 0.06), then used the VFR=Av formula to find the speed/velocity of section one. VFR== 0.063 m^3/s A== pi*r^2=pi*(10cm)^2=pi*(0.10)^2=pi*0.01 == 0.031415927 VFR/A=v...
  2. B

    Volume Flow Rate: Open vs Closed Valves

    Made an attempt at this Q but I'm unsure on how to do part c) or if I had even done part a) and b) right What difference does it make to the volume flow rate equation when the valve goes from open to closed? Any help would be appreciated! Thanks
  3. Izazo

    Outlet Volume flow rate from a steam turbine

    I am working Organic Rankine Cycle. I studied a number of research papers and in most of them, they have calculated outlet volume flow rate from the turbine or expander, but have not mentioned the calculations. So here are the available data; Pin = Turbine Inlet Pressure, 2.5 MPa Pout = Turbine...
  4. akin-iii

    I How do I derive a PDE for the volume flow rate of a tilting vessel?

    So the other day, I was pouring beer from a can to a mug and I obviously know the flow rate depends on the height of the beer from the bottom of the can (fluid level in the vessel), angle of tilt and I think time as well. I was wondering how to best model the PDE to describe such a phenomenon (...
  5. C

    Fluid Mechanics -- Volume flow rate

    Hey guys. I could use some explanation since I am new to FM: So my problem is the following one: Fluid flows with an average velocity 8 m/s in a pipe with diameter 3m. What is the volume flow rate? Now, I think the formula I got to use is Q= v.A Yet, I found my solution from a formula I found on...
  6. S

    Volume flow rate variation of a free air jet

    Hi, I recently did an experiment whereby we investigated the velocity distribution of air expelled from a round nozzle whose diameter, D, was 30mm. We have been asked to calculate the volume flow rate at distances of 2D, 6D and 10D along the centreline. We found the flow rates to INCREASE...
  7. J

    The Pressure Distribution in a Narrowing Tube with Increasing Fluid Velocity

    Homework Statement Question: For a fluid flowing within a horizontal tube, if the diameter of the tube narrows, will the fluid's flow rate increase, resulting in increased pressure in the narrowing and explain your reasoning. Homework Equations Volume flow rate = volume/time Volume = Area x...
  8. H

    Understanding G and γ in Volume Flow Rate Calculations

    Homework Statement what is G and γ mean here ? Homework EquationsThe Attempt at a Solution
  9. A

    Calculating Volume Flow Rate of Olive Oil at a Processing Plant

    Homework Statement At a processing plant, olive oil of density 875 kg/m3 flows in a horizontal section of hose that constricts from a diameter of 2.92 cm to a diameter of 1.20 cm. Assume steady, ideal flow. What is the volume flow rate if the change in pressure between the two sections of hose...
  10. M

    Volume flow rate and mass flow rate

    Hello there, so I have answered my question from fluid systems but the answer doesn't look right ;/ and I have no idea what have I done wrong. Can you please check and correct where it's wrong ? ;) here is the question: A pipe contains a gradually tapering section in which its diameter decreases...
  11. E

    Calculate Volumic Flow Rate for Air (kg/s) at 1 bar, 20 - 50°C

    Hey guys, can some of ou help me with this question: I need to calculate the volumic flow rate for air by using the ideal gas law. Things i know from the assignment: molarmass = 28,96 kg/kmol Pressure = 1 bar mass flow = 2 kg/s t in = 20 degrees celcius t out = 50 degrees celcius (sorry for bad...
  12. Q

    How do you calculate the mass flow rate, volume flow rate and velocity

    How do you calculate the mass flow rate, volume flow rate and velocity of a 6 bar compressed air supply through a 2mm tube? This is all the information I have been given. Is there any theory that could help me here? I can't seem to find much on the internet, so I have no clue where to begin...
  13. I

    Calculating volume flow rate per unit width of a plate ( Fluid Mechanics )

    This is the question The flow of a fluid between two large flat parallel plates normal to the y direction is fully developed and steady. The plates are a distance 2h apart in the y direction and the velocity profile, assuming y=0 is at the midpoint between the plate is V(y) = V_0(1-(y/h)^2)...
  14. T

    Volume flow rate through air ducts

    Homework Statement Air flows through two 8"x10" ducts that merge into a single 18"x14" duct. (Ducts are in 3D) The average speed of air in each of the 8"x10" ducts is 30 ft/s. What is the volume flow rate, of air in the 18"x14" section of the duct? Express the volume flow rate in ft^3/s...
  15. J

    Volume Flow Rate in a Pipe for Viscous Fluid

    Homework Statement Hi, my first post here! I have a Thermodynamics resit over the summer and I'm trying to get my head around viscous flow, I'm stuck at a question and need help! Thanks :) Glycerine discharges to the atmosphere through a circular pipe 100mm in diameter. The gauge pressure 50m...
  16. R

    Solving for Time in a Volume Flow Rate DE - Help Needed

    Hi all, So I've got a fairly straight forward problem to solve here regarding flow rate out of a tank with uniform cross-sectional area. I am treating this is a volumetric flow problem since there is assumed to be volume flow out of the tank, and volume flow into the tank. I have two Qout...
  17. K

    Help Understanding Volume Flow Rate / Bernoulli's

    Hey guys, just have a question because I'm having a little trouble understanding like how exactly to use the volume flow rate with bernoulli's equation. (wasnt sure which section to put this in but is more of a concept question using homework examples) Like the volume flow rate i understand...
  18. M

    Calculate Velocities and Volume Flow Rate?

    A horizontal pipe tapers uniformly from a diameter of 150mm to a diamter of 70mm and carries water (1000kgm3). The pressure at the wider diameter is 100kPA and the pressure at the smaller diameter is 60kPA. Calculate both velcoties at either end and the volume rate of flow.
  19. K

    Volume Flow Rate, Velocity, Factors

    Homework Statement By what factor does the flow rate decrease when a water pipe of diameter 20 cm with a 10 cms^-1 flow rate, splits into two smaller pipes of diameters 11.54 cm and 16.33 cm? Homework Equations Q(volume flow rate)=(average velocity)(cross sectional area of flow) The...
  20. J

    Thermodynamics (Mass flow rate & Volume flow rate)

    Homework Statement Steam at 400oC enters a nozzle with an average velocity of 20 m/s. If the specific volume and the flow area at the inlet are measured as 0.1 m^3/kg and 0.01 m^2 respectively, determine (a) the volume flow rate in m^3/s, and (b) the mass flow rate in kg/s Homework...
  21. C

    Calc Volume Flow Rate of Water from Tap (45mm ht)

    [b]1. Homework Statement Tap water flowing has an cross section area of 1.2cm^2 near the tap. after a height, h=45mm the cross section becomes 0.35cm^2...find the volume flow rate of water from the tap Homework Equations g=9.8m/s^2 The Attempt at a Solution i think of using these...
  22. O

    Calculate Volume Flow Rate: Pressure & Speed

    Hi there, I have a lab project. Part of the project is to calculate the volume flow rate, I have 2 tubes,radius' are known , density of the fluid is known and pressure is known. How can i relate the pressure to speed?
  23. A

    Calculate Time to Fill Bathtub with Volume Flow Rate

    Ok another stupid/smart question, I got a bath with x m^3 volume. And a water flow rate of a tap is y m/s. I also know pressure and velocity. How can I calculate time to fill up bathtub? I know it's simple but I can not figure it out!
  24. S

    Calculate Volume Flow Rate: Hose Diam & Cliff Height

    Homework Statement To better fight fires in your seaside community, the local fire brigade has asked you to set up a pump system to draw seawater from the ocean to the top of a steep cliff adjacent to the water where most of the homes are. 1. If the cliff is 12.0 m high, and the pump is...
  25. B

    Fluid Dynamics: Using Bernoulli's equation and Volume Flow Rate

    Homework Statement Water flowing out of a 15.0mm -diameter faucet fills a 1.50 L bottle in 5.00s. At what distance below the faucet has the water stream narrowed to 10 mm in diameter? Homework Equations Bernoulli's equation: P_1+pgh+1/2pv^2=constant Q(volume flow rate)=vA Continuity...
  26. K

    Volume Flow Rate: Solve for Water Leaving Faucet in cm^3/s

    Homework Statement A pump at ground level creates a gauge pressure of 102 kPa in the water line supplying an apartment building. The water leaves the tank into a pipe at a negligible speed. It travels up 10 m through the building and exits through a faucet. The cross-sectional area of the...
  27. D

    Calculate Average Blood Speed with Volume Flow Rate | Physics Problem Help

    Volume Flow Rate, Help? 1. The problem statement, all variable and given/known data The volume flow rate in an artery supplying the brain is 3.5E-6 m^3/s. (a.) If the radius of the artery is 5.4E-3 m, determine the average blood speed. (b.) Find the average blood speed at a constriction...
  28. J

    Should volume flow rate measurements be corrected for different conditions?

    Hi I have a question about measuring volume flow rate with a laminar flow element. I read the pressure difference across the element (mmH2o) and I get volume flow rate (cfm) from a calibration law. If that calibration law was obtained at standard conditions, would I have to correct it for...
  29. M

    Simple volume flow rate calculation

    [SOLVED] Simple volume flow rate calculation A 1.0-cm-diameter pipe widens to 2.0 cm, then narrows to 0.5 cm. Liquid flows through the first segment at a speed of 4.0m/s. The speed in the second segment is 1m/s, and the speed in the 3rd segment is 16 m/s I thought that volume flow rate was...