Flow rate Definition and 496 Threads

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. J

    Fluid dynamics - mass flow rate -dimensionless number

    (a) Is it true that if the mass flow rate of a gas is low, say 2g/s (grams per second), the friction losses and other losses in the piping will be negligible? (b) If it is true that losses in the piping are negligible, is it the Euler's dimensionless number that we can use to prove this...
  2. F

    Calculating the change in flow rate with varied height.

    How would i calculate the change of flow rate when i have the intial rate, the length, and diameter of tubing ? Say I get an initial flow of 100gph and the tubing the water travels through is .5inch diameter and 16 inches long. What is the flow at the end of the tubing? Could I also calculate...
  3. 1

    How to Calculate Flow Rate in a Tapered Pipe with Pressure Difference?

    Homework Statement An alcohol flows smoothly through a horizontal pipe that tapers in cross-sectional area from A1 = 43.7 cm2 to A2= A1/4. The pressure difference Δp between the wide and the narrow sections of the pipe is 8.8 kPa. What is the volume flow rate ΔV/Δt of the alcohol? The density...
  4. A

    How to find the flow rate trough a pipe using pressure drop

    Hi, I want to know how high the flow rate trough a pipe is (outlet), but I only now the pressure difference (0.7MPa or 7 bar), and the diameter of the pipe. At what speed (or for that matter volume) does air leave a pipe when the pressure difference is 7 bar, and the diameter is 25.4mm...
  5. R

    Flow Rate vs Rev/Gal: Understanding Relationship & Calculation

    I want to pump fluids (flow rate) through a drill string to a downhole motor some distance beneath the surface building up some differential pressure (psi). depending on the amount of differential pressure and the flow rate (gpm) the motor rotates at some rotational speed (rpm). what is the...
  6. R

    Calculating Flow Rate in Horizontal & Vertical Pipes

    Homework Statement A liquid is flowing through a horizontal pipe whose radius is 0.02m. The pipe bends staight upward through a height of 10.0m and joins another horizontal pipe whose radius is 0.04m. Homework Equations what volume flow rate will keep the pressures in the two horinontal...
  7. O

    Can Fluent 6.3.26 be used to analyze flow rate and heat in a copper tube?

    hello all, i am from electrical background and for a project i need to analyse the flow of oil through a hollow copper tube when the tube is subjected to some amount of heat. the outcome should tell me if the heat will be absorbed by the oil and what would be the stress points when i apply...
  8. U

    What is the mass flow rate of the water?

    Hello, I have some physics homework and I'm not looking for the answers. Rather, the textbook I currently use does not seem to be doing a good job (in my opinion) in explaining the topics. If anyone has seen some of these questions before and know what textbook they are used in, please let me...
  9. M

    Mass flow rate of cooling water in Diffuser

    Hello Everyone, I am Mayur I am working on a system, in the system there is one diffuser through which exhaust gases at 3000K are flowing at a rate of 170Kg/s. The material of diffuser is Stainless Steel. The diffuser is double walled type with cooling water flowing between the walls. I need...
  10. Y

    Solve for Cold Surface Temp. of Slab with Heat Flow Rate 240 W

    Homework Statement The absolute value of the heat flow rate through a slab of area 0.83 m2 is 240 W. The thickness of the slab is 1.4 cm and its thermal conductivity is 0.6 W/(m·K). If the hot surface of the slab is at 40°C find the temperature of the cold surface. Homework Equations...
  11. B

    Will a Book on a Ziplock Bag Create a Constant Water Flow Rate?

    Hi I am a post-doc student in a field having very little to do with physics and math. currently I am designing an experiement and have (i hope) a relatively simple question. here is the scenario: A ziplock bag (or similarly non-elastic reservoir) contains water, but is not maximally...
  12. L

    Fluid Dynamics (flow rate, Re,)

    Homework Statement An average person has about 5 litres of blood in their body. The heart circulates all this blood around the body in only about 1 minute. Find the time averaged volumetric flow rate Q of the aorta, which is a pipe of inner diameter 2.2 cm. Find the time and space...
  13. D

    How can you determine the mass flow rate

    Homework Statement How can you determine the mass flow rate, given that net power output is 100 MW, of the cooling water if it enters the condenser at 20 C and leaves at 35 C. Homework Equations The Attempt at a Solution I thought that mass flow rate is the same all through...
  14. V

    How Can I Form a Differential Equation for a Sphere's Flow Rate?

    Homework Statement I just need to get these eqn's together to form a DE Homework Equations Q = CA*sqrt(2gH) = -dV/dt and V = pi/3 * H^2 * (3*r - H) These eqn's refer to a sphere which has a flow Q of fluid out the bottom of said sphere. The radius of the sphere is r, the height H is from...
  15. 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...
  16. V

    Calculating Flow Rate: Oil in a Pipe

    Homework Statement Oil flowing through a pipe, measured to be 135kPa 15m from the end and 88kPa discharging from the end. The diameter of the pipe is 1.5cm, the density of the oil is 876kg/m^3, and the dynamic viscosity is 0.24kg/m*s. Find flow rate for: a) horizontal b) inclined 8...
  17. 0

    How can I calculate the mass flow rate out of a PSV valve?

    Hi all, I am designing a pressure relief system for a high pressured gas (air) system. System consists of a highly pressurised gas receiver with PSV mounted driectly on it which vents via tailpipes to atmosphere. I know the max mass flow rate out of the container I know the back pressure...
  18. J

    Compressible Fluids: Getting Desired Volume/Mass Flow Rate

    I'm having trouble calculating the required pressure to get the desired volume flow rate (at outlet conditions). I'm no expert at compressible fluid systems, but I ended up being the one to design it... The system must feed helium vertically through 3/8" ID, 112 ft long tubing (ID can vary, I...
  19. V

    Jet Engine Mass Flow Rate calculation

    hi how to find air mass flow rate in jet engine? we are using thrust/Isp equation to find the mass flow rate for rocket equation. is that any formula available for finding the mass flow rate in jet engine
  20. W

    Flow Rate of a Deflation Balloon

    A drug delivery infusion pump is made out of thick synthetic rubber and has a very small outlet. The balloon pump is filled with 500mL liquid drug and is now inflated into a ball shape. The drug will exit from the very small outlet at a nearly (but not always) constant flow rate of 5mL/hr (takes...
  21. W

    Flow Rate of a Deflation Balloon

    A drug delivery infusion pump is made out of thick synthetic rubber and has a very small outlet. The balloon pump is filled with 500mL liquid drug and is now inflated into a ball shape. The drug will exit from the very small outlet at a nearly (but not always) constant flow rate of 5mL/hr (takes...
  22. S

    Help! Calculating Water Flow Rate in Pipe

    Please help I'm going round in circles! Water on tank 12m high, feeding pipe 200m long and 125mm diameter. Open end. Given friction factor of 0.008 for the pipe and total of 3.2K for various fittings. Asked to find water flow rate in Kg/s in the pipe. Been looking at this for ages...
  23. J

    Equation relating mass flow rate to pressure drop

    Hi I am designing a heat exchanger. I know the mass flow rate required for cooling. I have calculated the pressure drop for current design. How do I work out if the size if the heat exchanger can handle the flow rate ? Does the mass flow rate depend on the size of the heat exchanger tubes ...
  24. M

    Flow and Flow Rate: Determine Rate & Pressure Change

    Homework Statement A horizontal water main with a cross-sectional area of 220 cm2 necks down to a pipe of area 55 cm2. Meters mounted in the flow on each side of the transition coupling show a change in gauge pressure of 85 kPa. Determine the flow rate through the system, taking the fluid to...
  25. A

    How Is Mass Flow Rate Calculated Through an Orifice?

    hi all, First all my disipline is not fluids so this is why asking for little help here on the following. Basically i have all the required information but i can't seem to figure out how the answer to the mass flow rate of an orifice is obatained, its doing my head in, if anyone could...
  26. M

    Maximizing Water Circulation: Tips for Calculating Flow Rate in a 2000L Pond

    need help in flow rate... hi, i am just new here... hope anybody could help me here... i am making a pond just like my username says... my problem is, my pond is around 2000L and has an outlet of 2inches at the bottom corner of the pond. how do i compute the flow rate, coz i want to...
  27. A

    Effect of Downstream Pressure Fluctuations on Choked Mass Flow Rate

    What would be the effect on a choked mass flow rate if there were fluctuations in the downstream pressure? Thanks
  28. M

    Water flow rate through a filter

    Homework Statement Hello everyone, I'm working on a summer project with filters (they're rather simple). Anyways, my professor suggested that I calculate flux through the final surface of the filter, which I guess is speed of water? Long story short, I'm having a real problem with this... I...
  29. R

    Calculate Flow Velocity and Hole Diameter in Water Tank Problem

    1. A large tank isopen to the atmosphere and is filled with water. A small hole is 16m below the surface of the water. If the flow rate of the water is out of the hole is 2.5e^3 m^3/min, calculate: a)the velocity of the water as it leaves the hole and b) the diameter of the hole. 2. Let's say...
  30. G

    Hydrolics, Forces and flow rate.

    Hi, I'm currently trying to work out the forces involved in raising a traffic barrier. It works using hydrolics. It has a motor that has a speed of 1400 rpm and 1/3 hp. the torque of the motor is 200Nm the pump is a lobe pump and has a delivery of 1.5 l/min. The pump will move the...
  31. E

    Find Mass Flow Rate: Formula & Explanation from a Rocket

    I want to clarify this because I'm still not sure how to find the mass flow rate, for instance from a rocket. I still puzzled from the formula that describes the mass flow rate which is \frac{dv}{dt}. This the formula that I'm currently looking over but I'm not sure if its this formula to find...
  32. A

    Solve Mass Flow Rate Problem: U(max) at R=0.16 m

    Homework Statement At a point upstream the measured mass flow rate is 10 kg/s, downstream of this location the velocity profile is measured and obeys the relationship u(r) = U(max)(1-(r/R)^(1/5)) where R is 0.16 m. Find U(max). The diagram provided with the question is provided below...
  33. B

    Calculating Maximum Flow Rate for Vacuum Chamber

    I'm now making a vacuum chamber. The gauge pressure inside the vacuum chamber is about 250 mmHg. There will be some gap on the operating surface, about 2 mm width. The thickness of the gap is between 1 - 10 mm. What is the maximum flow rate per meter for the vacuum chamber?
  34. 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...
  35. 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...
  36. S

    How to Calculate Flow Rate with Given Parameters?

    I'm trying to get my head around this question but having missed a few lecture through illness I'm going round in circles. Water is fed from a tank 12m above ground along a pipe 200 m long with a diameter of 125mm. Pipe frictyion factor is 0.008. K factors for the fittings, (tank exit, valve...
  37. D

    Calculate Flow Rate: Inlet & Outlet Diameters & Pressures

    Is it possible to calculate the flow rate of water through a restrictionless device (a tank, for example) if you know the inlet & outlet diameters and pressures? I've been looking all over, but all I can seem to find is formulas for pressure drop in a length of pipe... Thanks!
  38. J

    Calculating the Mass Flow Rate for Point C

    Homework Statement see attachment Homework Equations Av=dV/dt mass flow rate =roe*dV/dt The Attempt at a Solution the velocity at point c is 50m/s and the area of the opening is 0.04m^2. (50m/s)(0.04m^2)(1000kg/m^3)=2000Kg/s
  39. H

    Solving Flow Rate Through Pipes with Pressure Difference

    Homework Statement A horizontal pipe 10.0cm in diameter has a smooth reduction to a pipe 5.00cm in diameter. If the pressure of the water in the larger pipe is 8.00x10^4Pa and the pressure in the smaller pipe is 6.00x10^4Pa, at what rate does water flow through the pipes? Homework...
  40. M

    Calculating diameter of a filter using only flow rate

    i have got a problem with a calculation involving a filter, i hope you all with lend me a helping hand. to calculate a diameter of a cylinder is rather easy, but how to determine the size of the water filter knowing only the flow rate of the pipe, diameter of the piping and the pressure of...
  41. W

    Question About Mass and Mass Flow Rate Relations

    Mass is the product of density and volume. Mass flow rate is the product density, velocity, and cross-sectional area. (It's the derivative of mass with respect to time.) Bare with the syntax please... Looking at a sphere within a larger sphere, the volume of the difference is...
  42. J

    Calculating Water Viscosity from Flow Rate

    Homework Statement Find the viscosity of water given that; flow rate (cm^3 s^{-1}) = 2.0 height from tube (m) = 0.1 l (m) = 0.2 r (mm) = 1 \rho = 1000 g = 9.81 Using the equations; x = \frac{Flow Rate}{Height} x = \frac{\pi \rho gr^4}{8l\eta}The Attempt at a Solution Okay so first, and...
  43. V

    Calculate Flow Rate from Inclined Plate | Physics Problem Solution"

    hi, problem: I have a flat plate of dimensions 2.6*2.2, above which a 4mm sheet of water is there(stagnant). Now i will lift the plate on one side, with certain rate till i reach the plate inclination some 10 deg. Physics: when i start lifting the plate on one side, water starts flowing...
  44. A

    Calculating Volume Flow Rate for Apartment Building Faucet - 102 kPa Pressure

    I need help with flow rate please! 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 10m up through the building and exits through a faucet...
  45. J

    What is the Average Flow Rate in a Room with Circular Ducts?

    Homework Statement A room measures 3.5m by 4.5m by 6.0m. If the heating and air conditioning ducts to and from the room are circular with diameter of 0.30m and all the air in the room is to be exchanged every 12 min, (a) what is the average flow rate ? Homework Equations A1*V1=A2*V2...
  46. 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...
  47. R

    Expression for height of water as a function of time given flow rate in and out

    Homework Statement Consider the filling of a horizontal wedge-shape trough of height H, length, L, and width, B with water. (Imagine a water trough for horses with ends that are matching triangles). The volumetric flow rate of water in is given by Qi and the flow rate out by Qj. Obtain an...
  48. A

    Solving Flow Rate Problem to Increase Pipe Diameter by 5.3

    Homework Statement An irrigation pipe of diameter 20cm carries water at an average speed of 0.1 m/s. By what factor must the pipe diameter be increased to achieve a flow rate of 1.00 m^3/min? The answer given is a factor of 5.3. Homework Equations Poiseuille's equation Q =...
  49. 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...
  50. S

    Mass flow rate of cooling water in condenser needed

    Homework Statement Adiabatic Steam turbine produces 4000 kW Steam is fed at 21 bar/475 deg C Exhaust is saturated steam (P=0.1bar) Exhaust is fed into condenser where it is cooled to 30 deg C Problem asks for flow rate of cooling water supplied to condensener if water enters at 15 deg C...
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