What is Pipe flow: Definition and 73 Discussions

Pipe flow, a branch of hydraulics and fluid mechanics, is a type of liquid flow within a closed conduit (conduit in the sense of a means of containment). The other type of flow within a conduit is open channel flow.
These two types of flow are similar in many ways, but differ in one important aspect. Pipe flow does not have a free surface which is found in open-channel flow. Pipe flow, being confined within closed conduit, does not exert direct atmospheric pressure, but does exert hydraulic pressure on the conduit.
Not all flow within a closed conduit is considered pipe flow. Storm sewers are closed conduits but usually maintain a free surface and therefore are considered open-channel flow. The exception to this is when a storm sewer operates at full capacity, and then can become pipe flow.
Energy in pipe flow is expressed as head and is defined by the Bernoulli equation. In order to conceptualize head along the course of flow within a pipe, diagrams often contain a hydraulic grade line (HGL). Pipe flow is subject to frictional losses as defined by the Darcy-Weisbach formula.

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  1. N

    How to maintain flowrate and pressure head in a pump?

    Pump is supply fluid to the 35 nozzles through 3 inch pipe and manifold.At nozzle the pressure is 32 m and pressure at pump outlet is 30 m .The flow rate required at nozzles is 500 lpm. Pump can deliver 860 lpm at 24 m head.pump size 100x100 mm 1)how delivary pipe size affects the pressure head...
  2. A

    Bernoulli equation and parallel pipe branch

    Hello! I have a question regarding the application of the bernoulli equation and calculation of the flow through a parallel pipe branch. It's more the basic understanding how the flow will establish. You can find a sketch attached to follow my explanation. Let's assume I have a pipe with...
  3. V

    Radiation heat transfer in channel flow

    Hi guys, I am confused about the heat transfer mode of between two contacting material, especially in a channel flow. Obviously, conduction or convection dominate the heat transfer process in the process with low object temperature . But I am not sure if I have a fluid of 500 Kelvin, flowing...
  4. M

    Fluid Mechanics problem: Oil pressure calculations in pipe flow

    Problem Statement: An oil with density 900 kg/m3 and viscosity 0.18 Ns/m2 flows through a circular pipe which inclines upwards at 40° to the horizontal. The length of the pipe is 10 m and the diameter is 6 cm. The fluid pressure at the lower end of the pipe is 350 kPa and the pressure at the...
  5. nn2e19

    Hole Sizing to Drain Fluids [Pressurized Container]

    Hello, I want to size my system to be able to get rid of fluids without any head buildup within the container. I am just a bit confused as to what formula I should use. My problem is summed up in the following schematic. Note that P1>P2, I have assumed H=10^(-4)m and my flow rate is 0.1 m3/s...
  6. Sizhe

    Pipe flow with precipitation at boundary

    Homework Statement Consider a plug flow (slippery walls) with a uniform velocity ##U## in a circular pipe of diameter,##d## and length ##L##. The fluid is a supersaturated solution with a concentration ##c##. At the pipe wall, precipitation of solute happens at a net reaction rate per unit area...
  7. M

    Temperature drop in an insulated pipe over 12 hours

    Hello all, I have been having some problems and would appreciate any help: I have a length of insulated pipe filled with engine oil at rest, the variables are as follows: Toil: 40 oC Tair: 5 oC h1 (LO): 3600.63 W/m2/K r1 (pipe inner): 0.1 m r2 (pipe outer): 0.1095 m r3...
  8. Oscar Gonzalez

    How to calculate flow loss between 90 and 45 degree fittings

    Hi everyone. Let me give a little bit of background on the problem I need help understanding. I want to plumb an aquarium that has a sump and move the water from the sump to the main aquarium using a pump and 1" PVC pipe. The total system pipe length is going to be roughly 10 feet total with...
  9. A

    Ansys Fluent transient pipe flow

    Hello, I am doing a relatively simple problem, but i can't initialise it. I have hot water at 400K moving inside a copper pipe at 300K. I would like to see the time it takes for the copper pipe's temperature to increase to 400. However I can't seem to initialise the temperature of the pipe...
  10. A

    Brain fade/idiot moment - simple question about pipe flows

    Stupid question: I have the following pipe configuration: Working fluid = ambient air Pipe1 = 6 inch ID x 24 inch length Expansion1 = 2 inch length Pipe2 = 8 inch ID x 2 inch length Fan1 = assume 200 CFM @ 2860 rpm, 0.05 inH2O Contraction1 = 2 inch length Pipe3 = 6 inch ID x 12 inch length...
  11. R

    Pressure drop calculation

    I have a pump running at 400rpm with 8" inlet and outlet with head 30 ft 500 gpm. Now I am planning to reduce the discharge line to 6" . Assuming the flow rate and speed constant the velocity in the pipe will increase. How do I calculate the change in head?
  12. G

    Pipe Flow Calculation: GPM Through Pipe Level Section

    I used to have a slide chart that gave gpm through a level section of pipe (1/2" - 6") by measuring how long the exit stream was when it had dropped 4". Imagine a framing square with the blade on the pipe and the tongue hanging down in the stream. Slide the square out until the stream is...
  13. CollegeCourt

    Split Pipe Flow: Multiple Inlets and Outlets (Bernoulli's)

    http://tinypic.com/view.php?pic=mhvarc&s=9#.WD__u_mLTIU Hey guys, So, I've got this problem, attached. I've used Bernoulli's to produce P1 + (1/2)p(u1)^2 +P2 + (1/2)p(u2)^2 = P3+ (1/2)p(u3)^2 +P4 + (1/2)p(u4)^2 +P5 + (1/2)p(u5)^2, Plugging in the values you get 82500 + P2 + 500(u2)^2 = P3 +...
  14. M

    Some questions on pressure drops and head loss in pipe flow

    I would like to ask you that why pressure drop is constant through pipe? How can we know that dP/dx=constant? Thank you.
  15. A

    How Does Closing a Valve Affect Flow Rates in Multi-Suction Pipe Systems?

    If I a pump with a main suction header and 4 smaller branch connections of difference sizes. Let's say for this example we have (2) 3", (1) 1", and (1) 2". Also let's say our pump is requiring 20 gal/min. The flow rate of each branch would be proportional to the area of the pipe correct? flow =...
  16. A

    Theoretical Pipe Flow: Understanding Poiseuille's Law

    Hey guys, I am doing an internship and I have had some thoughts about fluid flow that have come up and I am having trouble fully grasping some concepts due to no one being able to thoroughly explain any answer that they might come up with. So I have a crude understanding of some fluid dynamics...
  17. A

    How Can I Increase My Lawn Sprinkler System's Flow Rate?

    I have a DIY project for a lawn sprinkler system but my flow rate is insufficient : if my setup is to work properly, the sprinkler manufacturer suggests a flow rate of 2880 litres per hour at a pressure no less than 2 psi. I measured the flow rate of my current garden faucet, which is connected...
  18. M

    Velocity as a function of area in pipe flow

    There is an equation which perplexes me and it is about calculation of average velocity in a pipe but over area. In the image, the velocity is already function of diameter, i.e, u=u(r) so how can we think velocity as a function of area? Source: Fluid Mechanics, Fundamentals and...
  19. M

    Calculating Air Pipe Flow System Rates & Velocities

    I'm working in an engineering internship after my first year and we haven't covered fluid dynamics in my program yet. I've been assigned to find flow rates and velocities in several branches of a suction (dust collection) system in our factory. The main branch has a diameter of 30" and is...
  20. A

    Fluid mechanics and pipe flow questions

    < Mentor Note -- thread moved to HH from the technical engineering forums, so no HH Template is shown > Pics are attached, my concerns are with question 4 and 5. For q4 -which way is flow? How do we know? -the working then goes on to say that energy loss is compensated by increasing in...
  21. D

    Laminar Pipe Flow: Displacement, and Momentum Thicknesses

    Hello. I'm new to the forums. I apologize if I have posted this in the wrong topic area. I'm new to this hydrodynamics area and I'm trying to learn the concepts of boundary layer thicknesses. My question is about laminar pipe flow and calculating displacement and momentum thicknesses. I was...
  22. A

    [Conceptual Question] Fluid Mechanics Analysis of Pipe Flow

    Homework Statement As shown in the figure, if the pipe net work is shifted bodily by 10m vertically up the tank, and all the other conditions remain the same as the previous figure. Will the volume flow rate change? Or I rephrase it as, in the calculation of elevation head of pipe flow, is the...
  23. D

    Measuring Flow Velocity in Pipe Expansion: Laminar vs. Turbulent | Explained

    Hi there, I have a double-barreled question for you all. So I have two pipes connected to each other. The first pipe is 0.64cm and has a Re = 5000, the second pipe is 4.5cm and has a Re = 700. The two are connected so that the gas expands from the the first pipe to the second. Now, I wish to...
  24. J

    Turbulence in pipe flow (Reynold's Number)

    I have some confusion about how blockages result in the laminar/turbulent flow of fluids in pipes. From my understanding, there is a certain diameter of a blockage in a pipe that will cause the flow to transition from laminar to turbulent (depending on the velocity of flow, etc.) What is the...
  25. M

    Calculate Water Pipe Flow for Output Temperature of 60 Celsius

    Hey Guys! This is my first post so I apologize beforehand if there are any mistakes with my post :D But my question is... I have 2 water pipes that are connected to one pipe in the middle, but the distance from the 2 water pipes to the connection point are not necessarily the same. The...
  26. S

    Fluid dynamics, Pipe Flow, Hagen Poiseuille, Darcy's equation

    Homework Statement A water injection line is made from smooth capillary tubing with inside diameter D = 25.0 mm . If the length of the pipe is 0.75 m and assuming laminar flow is present up to Re = 2000, find (i) the maximum average velocity at which the flow is laminar (ii) the pressure...
  27. P

    Bernouilli's principle pipe flow problem

    Homework Statement On a horizontal pipe with flowing water on point 1 there is a vertical pipe with water up to some point. On another point 2, we have a pitot tube (L shaped) against the water flow and the lever on the vertical part is higher that on point 1. If the water flow stops what...
  28. E

    Fluids Problem - Dimensional analysis, pipe flow, propeller

    Homework Statement I have a tutorial question I have been struggling with. The problem is: The flow through a closed, circular sectioned pipe may be metered by measuring the speed of rotation of a propeller having its axis along the pipe central line. Derive a relation between the volume...
  29. D

    Help a College Student With Pipe Flow Calculations

    a newbie here so not sure if this is in the right place! i'm in the middle of a paper that I'm doing for college, investigating the effects of roughness on air flow. i set up 2 pipes, 1 rough and 1 smooth (800mm long, 36mm diameter), in a wind tunnel, measured the velocity of the air entering...
  30. J

    Pipe Flow: Neglecting Pipe Length

    In the diagram attached I have a pipe (standard concrete) that is going from point A (Entrance) to point B (Exit). Standard water is the fluid within the pipe. Point A (entrance) has a constant uninterrupted supply of water at a velocity of 0.7m/s, how do I find the correct velocity at point B...
  31. T

    Pipe Flow Q: Frictional Head Loss in Tank?

    Homework Statement This is in the pipe flow section and the solution treats this question like a pipe. Here is the solution: As you can see I circled the pipe flow equations in red. If this is the case shouldn't there be frictional head loss, hf, caused by the walls of the tank? I...
  32. M

    Thermodynamics: Vertical pipe flow of geothermal water

    1. Water at T1=240 C and P1=16 MPa is at 2 km depth. A drilling hole with diameter 0.2 m has the water flowing up with mass flow rate at 2 kg/s. The hole is considered adiabatic(no heat transfer). I need to find the following values at the top of the hole: Enthalpy(h), temperature(T2)...
  33. B

    What Equation Models Boundary Layer Thickness in Early Stage Pipe Flow?

    Hi I cannot find an equation for a boundary layer in a pipe flow (laminar). I am looking for an equivalent of the equation δ(x)=4.91x/(√Re) that works for a flow between plates (x is the distance downstream). The thing is- I am looking for BL thickness for still undeveloped flow. I would be...
  34. R

    Pipe flow question, finding diameter

    Homework Statement Water pumped to a cooling plant through a 4km long cast iron pipeline. power available is 30kW. what pipe diameter is required to ensure a mass flow rate of 100kg/s. Homework Equations The Attempt at a Solution I know you have to guess a value and find it...
  35. S

    Finding the k value in a pipe flow question

    I am trying to do a pipe flow question but I am having trouble understanding how they have calculated the k values. Example question 1.1 attached & appendix A1 attached. We have to use appendix A1 to find the k values. I have tried using interpolation to get the k values from the example...
  36. J

    Which Surface Roughness value to use for pipe flow friction factor

    I am trying to predict pressure drop in a pipeline with a range of different materials. I have used a surface profilometer to measure the surface roughness of the different materials and I have values for various surface roughness variables - Ra Rz Rmax Rq Rm S Sm R3z Wt and a range of other...
  37. S

    Can One Pressure Sensor Accurately Measure Flow Rate in a Pipe System?

    Hello, I am stuck on a pipe flow measurement problem and I would love if some excellent minds would help me out. I have a robot that sprays paint, and there is a motor pump providing the paint to it. I need to be able to measure the flow rate (velocity) of the paint going through the nozzle...
  38. Peeter

    Justifying steps in the Navier-Stokes calculation for simple circular pipe flow.

    Homework Statement In [1], problem 2.3 (ii), we are asked to show that for a pipe with circular cross section r = a and constant pressure gradient P = -dp/dz one has u_z = \frac{P}{4 \mu}\left( a^2 - r^2 \right) u_r = 0 u_\theta = 0 References: [1] D.J. Acheson. <em>Elementary fluid...
  39. W

    Effect of inserting obstacle to the velocity in a pipe flow

    Hey guys, i want to ask about what the effect of inserting obstacle to the velocity profile of a pipe? I mean when i insert a cube obstacle inside a pipe, how the velocity profile look like? let's say the velocity profile is in laminar flow. Thanks
  40. B

    Understanding the Transition to Turbulent Flow in Pipe Systems

    Hi As fluid enters a pipe and progresses further down, does the shear stress at the wall reduce whilst the boundary layer increases and viscous forces take over? Thanks
  41. A

    Pipe Flow Software: Calculate Flow Rate, Pressure Drop, Flow Rate & Temp Change

    I am looking for software to calculate flow rate, pressure drop, flow rate and temperature change in facility piping. Any suggestions?
  42. J

    Flow rate relation? (velocity distribution in pipe flow)

    i have this question which asks me to find the average flow velocity in a pipe, BUT based on flow rate relation and not statistical average what is the flowrate relation?
  43. C

    Maximizing Plug Flow Efficiency for CSTR Blending: Expert Tips & Strategies

    I am trying to formulate a plug flow for section of my model. In my model, I've series of CSTR that are linked with the plug flow. The output of the plug flow model is the CSTR model. My main focus is blending CSTR and plug to replicate a residenc time distribution. However, i need a plug flow...
  44. C

    Calculating Gas Flow Rate in a 180km Stainless Steel Natural Gas Pipeline

    1. The pressure at the start of a 180km stainless steel natural gas pipeline is 4Mpa and at the end is 2Mpa. If the diameter of the pipe is 0.4m, what will be the gas flow rate through the system? (ignore losses other than friciton) (for natural gas, \rho= 40kg/m3, \mu= 11x10-6 Pas2...
  45. C

    Fluids; pipe flow rate problem

    1. The pressure at the start of a 180km stainless steel natural gas pipeline is 4Mpa and at the end is 2Mpa. If the diameter of the pipe is 0.4m, what will be the gas flow rate through the system? (ignore losses other than friciton) (for natural gas, \rho= 40kg/m3, \mu= 11x10-6 Pas2...
  46. W

    Which roughness value (Rz, Ra, ) to use in pipe flow equations

    Hello, I'm currently doing a project were I have to design a tube through which a fluid will flow at > 10 m/s. I am validating my calculations and want to use the correct roughness values. The material is a plastic deposited using rapid prototyping. I have measured: Ra = ~7.5 - 8 Rz =...
  47. S

    Pipe flow calculation challange

    Homework Statement every where we require at least 3 variables out of 4(l,d,q,hf)l=length,d=diameter,q=flow rate, hf=head loss due to friction. assume water and e=0.02(roughnss coeff) what shall happen if 2 of them are known and remaining 2 unknown ex.known=l,d; unknown=hf,q; we also know...
  48. J

    Can a Valve Create a Time Lag and Prevent Water Mixing in a Pipe System?

    Hi guys, Right, here is the situation. Consider a long coil of pipe containing water with a thermostatic valve at the outlet and a valve (this is the valve in question) at the inlet. The inlet is gravity fed by a large reservoir of water and the question is this: as the water leaves the...
  49. F

    Pipe Flow Question - Fluid Mechanics

    Hi, literally trying on the off chance that someone could help me. basically doing an individual project in my third year at nottingham uni. Over the last 6 months I've built a pipe rig to measure the pressure drop over a test section. Now my tutor is a bit of an idiot, and said the way i...
  50. P

    How Does Pipe Tapering Affect Pressure and Flow Rate in Fluid Dynamics?

    1. Water is flowing in a pipe from a tank to a nozzle. At some point (A) the pipe tapers from 160 mm diameter to 80 mm at point B over a certain length. Point A is 3 m above point B. The pressure at A is 100kPa and at B is 20kPa, both measured above the atmospheric pressure. The flow rate is...