What is laminar: Definition and 67 Discussions

In fluid dynamics, laminar flow is characterized by fluid particles following smooth paths in layers, with each layer moving smoothly past the adjacent layers with little or no mixing. At low velocities, the fluid tends to flow without lateral mixing, and adjacent layers slide past one another like playing cards. There are no cross-currents perpendicular to the direction of flow, nor eddies or swirls of fluids. In laminar flow, the motion of the particles of the fluid is very orderly with particles close to a solid surface moving in straight lines parallel to that surface.
Laminar flow is a flow regime characterized by high momentum diffusion and low momentum convection.
When a fluid is flowing through a closed channel such as a pipe or between two flat plates, either of two types of flow may occur depending on the velocity and viscosity of the fluid: laminar flow or turbulent flow. Laminar flow occurs at lower velocities, below a threshold at which the flow becomes turbulent. The threshold velocity is determined by a dimensionless parameter characterizing the flow called the Reynolds number, which also depends on the viscosity and density of the fluid and dimensions of the channel. Turbulent flow is a less orderly flow regime that is characterized by eddies or small packets of fluid particles, which result in lateral mixing. In non-scientific terms, laminar flow is smooth, while turbulent flow is rough.

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  1. F

    How do you I calculate the Laminar Boundary Layer Y in meters

    Homework Statement How do you I calculate the Laminar Boundary Layer Y in meters with Blasius Equation? I have an expression for U (m/s) and u/U and u(m/s) and also eta=0.1, 0.2...5.2. I am wondering how one could calculate the y laminar boundary layer (m), the y buffer boundary layer (m)...
  2. T

    Is this flow turbulent or laminar?

    Hello, is it a case of turbulent flow over a wing if the relevant Reynoldsnumbers are 350.000 to 1.500.000? Teoman
  3. F

    How Do Swimsuits Influence Laminar Flow and Reduce Drag?

    Hi I’m student at a french university, I have to present a project about swimsuit and I must carry out experiments. I’ve decided to work on the buoyancy of swimsuits, the flow around it and drag. To measure drag, I think I’ll drop a heavy ball wrapped in swimsuit material in the water and...
  4. 1

    What is the difference between laminar and turbulent flow?

    Hi, guys, i tried to read the definitions of laminar and turbulent flowon some of the website, but had difficult time understanding them. I am wondering if you guys can explain the above terms in more plain words?
  5. B

    Need Help Understanding Turblance / Laminar Flow

    Hi guys, first post and I hope I got the right forum. I have been doing some reading on fluid dynamics and there are a couple things I can't figure out. 1) When you light a candle or something and the smoke rises. It starts of nice and smooth, but then turns all turbulent after a little bit...
  6. X

    Fluid Mechanics: Inviscid flow v.s. Laminar flow

    Hey guys, I am kind of confused here but can you guys define for me inviscid flow and laminar flow? In my understanding, inviscid flow is when viscous effect is very weak and laminar flow is when reynolds number is in general, less than 2300. In that effect, does that mean that viscosity for...
  7. B

    Fluid with laminar flow going through a constriction in a pipe has low

    Hi What is the fundamental reason why a fluid with laminar flow going through a constriction in a pipe has lower pressure? Pressure is defined as force per unit area so the fluid particles must be hitting the pipe wall in the constriction with less force. Beetroot
  8. J

    What is the profile of the second fluid in laminar flow with two fluids?

    Hi I am working in an application where we pump a fluid in a water -filled tube, where the second fluid has a viscosity of 3-4 times the viscosity of water. We have laminar flow (Re around 20). If the fluids were 100% compatible (e.g. colored water vs clear water) I have determined that...
  9. V

    Heat transfer - laminar curved duct flow

    Hi, I'm trying to find some data on the entrance region of a curved duct with a rectangular cross section. Its a heat transfer problem where the fluid flows through a rotated duct. The distance of the duct is smaller than the entrance region for a straight rectangular duct of same...
  10. A

    What is an Eddy to Turbulent and Laminar Flow

    I understand that there can be turbulent flow and laminar flow. However, there is a term 'eddies/eddy' related to this which is not explained in my textbooks. What is an 'eddies/eddy'? :confused: Thanks in advance.
  11. H

    SS laminar blood flow through a spherical aneurysm

    Homework Statement What are the equations that govern the steady laminar flow of blood, modeled as an isothermal, incompressible, Newtonian fluid, through an aneurysm in the aorta, which is idealized as a “spherical bulge” located in a straight tube? Homework Equations ?? Assumptions...
  12. G

    Laminar Flow through a Tringular Duct

    I'm currently a freshman chemical engineer at Penn State and I've gotten so frustrated at fluid transport that I have resorted to online forums for one last desperate attempt to try and figure out what exactly is going on. This question is part of a long agonizing 2 week homework assignment and...
  13. D

    What is the solution for the laminar flow problem?

    Problem: Two horses pull a barge from rest in a canal filled with a viscous fluid that provides laminar resistance (FR = –kv). The two horses walk on each side of the canal so that their net force is applied exactly forward. The barge has a mass of 3000 kg and the donkeys pull forward with a...
  14. D

    How Does Laminar Flow Resistance Affect Barge Movement in a Canal?

    Problem: Two horses pull a barge from rest in a canal filled with a viscous fluid that provides laminar resistance (FR = –kv). The two horses walk on each side of the canal so that their net force is applied exactly forward. The barge has a mass of 3000 kg and the donkeys pull forward with a...
  15. I

    Shear Stress due to Laminar flow

    Homework Statement Oil of Density 888kg/m^3 and viscosity 0.8Pa*s is flowing in a horizontal pipe of diameter 0.15m. The local flow velocity at the centerline is 10m/s. find the shear stress exerted by the oil on the wall of the pipe. Homework Equations tau = -eta*(dv/dy) The...
  16. T

    How is the force in the Y direction developed in a simple laminar flow?

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  17. M

    "fully developed laminar flow" and fully developed turbulent flow"?

    Hi all, can you tell me what different between "fully developed laminar flow" and fully developed turbulent flow"? :cry:
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