Difference between revisions of "OpenFOAM/C2/2D-Laminar-Flow-in-a-channel/English"

2D geometry of channel

Meshing the Geometry

Solving and Post Processing results in Paraview

Validation with analytic result

I am using Linux Operating system Ubuntu 12.04 .

OpenFOAM version 2.1.1

ParaView version 3.12.0

Note that OpenFOAM version 2.1.1 is supported on ubuntu version 12.04

Hence forth all the tutorials will be covered using OpenFOAM version 2.1.1 and ubuntu version 12.04

Subsequently the tutorials were edited to latest versions

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L= 0.05 * Re * D

and D which is the channel height

and height is kept as 1 meters.

The Inlet velocity is 1 meters per second

And we are solving this for a Reynolds number ( Re ) equal 100

Therefore we are using a steady state incompressible solver for this case

right click >> new folder

simpleFoam folder of incompressible flow solvers

Now let me switch to the folder

make the necessary changes in the geometry,

boundary faces and boundary condition

Type run and press enter

cd constant and press enter

properties of fluid and a folder named polymesh

and

kinematic viscosity (nu) is set at 0.001 m²/s.

terminal type gedit blockMeshDict and press enter

Scroll down

Set the vertices for channel

next we have defined the vertices of the channel

mergePatchPair and edges are to kept empty.

Close the blockMeshDict file

type ls and press enter

Now Type ls and press enter

and wall functions for the channel case

initial flow conditions: p, R and U

epsilon ,k, nut,nuTilda

which are the wall functions

and

p , R and capital U which the are initial conditions of the flow

from the formula given in the slide

Where Ux, Uy and Uz are the velocity

components in the x, y and z direction

And U' ( dash ) = 0.05 times u actual

epsilon

C mu - constant

l – length of channel

Where epsilon is the rate of disspiation turbulent kinetic energy

C mu is a constant and its value is 0.09

And l is the length of the channel

Let me minimise this

are to kept default

for each of the boundary faces

terminal window type : blockMesh

To do this

In the command terminal type blockMesh and press enter

Meshing is done

Let me switch back to the slide

It is a Steady-state solver for incompressible, turbulent flow

let me minimise this

converged or it reaches its end time value

type: paraFoam and press enter

type paraFoam and press enter

This will open up the paraview window

View the geometry

The geometry can be seen here.

the drop down menu from solid color to capital U

play button of the VCR control

you can see the final value of velocity magnitude

left hand side top of active variable control menu

Click APPLY again

click on rescale to data

Scroll down

You can see Rescale , click on it

it attains a maximum uniform velocity at the center

Now let me switch back to the slides

the analytical solution for laminar flow in a

channel which is u(max)=1.5 Uavg

Using openfoam we obatain a velocity of 1.48 meters per second which is a good match

This brings us to the end of the tutorial

The File structure of channel

Obtained solution using steady state solver

Viewed the geometry in paraview

Validation with analytic results

Assignment

Solve the problem for Reynold Number 1500 and

validate it with the analytical result

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