fluent tutorial 2014

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Durham University Fluent Tutorial

The Durham Fluent 15 Tutorial

Introduction

This provides a short step by step guide to modelling an aerofoil using the Fluent package. The aimbeing to introduce you the important features of Fluent in the shortest possible space of time. Thistutorial is for Fluent 15.

Starting the Programs.

The fluid mechanics software packages are currently available on the C! "inu# service. Detailedinstructions on how to access this service are available on this website$https$%%www.dur.ac.uk%cis%linu#%service&facilities%

'll ()C! machines in the *ngineering and Computing !ciences building are +dual boot, you willneed to restart the machine and select +Ubuntu, to run a linu# system which will give you access tothe fluid mechanics software. The remotely accessible service +vega, currently -ctober /012features an older version of the software and do not recommend you use it.

Computing the Flow

This step is much more straightforward than meshing. n CFD modelling flow most of your timewill be taken meshing the problem and then analysing the results3 computation is the easy bit.

btain a terminal window. Usually 'pplications 4 'ccessories 4 Terminal

!tart Fluent by typing fluent at the terminal.

This pops up a window in which you can set your working directory and so on. ou need toensure that under +Dimension, the /D radio button is checked. 'fter a short while somethinglike Figure 1 will pop up.

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https://www.dur.ac.uk/cis/linux/service_facilities/https://www.dur.ac.uk/cis/linux/service_facilities/


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Figure 1: General View of Fluent 15

The key thing to note here is the bo# on the left hand side. This guides you through the solutionset6up. The plan is to work your way through each of the categories -sometimes these are called+Task )ages,2 from top to bottom setting variables3 boundary conditions and so on as you go.

There are three ma7or headings in this bo# -8eshing3 !olution !etup3 !olution and 9esults2 witha number of subheadings. :e will consider each heading in turn.

Meshing

This tutorial assumes that you already have a mesh. Fluent 15 features some meshing features notpresent in previous versions but you will need to look at the manual to discover more about thosefeatures.

To load in the mesh File 4 9ead 4 8esh. f you don;t have one there should be one on the web6page with this guide. This guide assumes that you will be using an aerofoil inside a soundary Conditions,

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!elect the flow e#it and change the +Type, to +pressure outlet,. Check the gauge pressure isset to ?ero -the default2 which is what we want.

!elect the flow inlet and change the type to +velocity inlet, set the velocity to be 15 m%s

ou can if you wish set the reference values to appropriate values for your aerofoil. These arethe values that Fluent will use to determine things like coefficients.

Solution Task Pages

The !olution 8ethods and !olution Controls can be left at default values.

n the +8onitors, task page make sure that the residuals are set to )rint and )lot

n the +!olution nitiali?ation, task page select +!tandard ntiali?ation,3 this picks up the factthat we have an inlet velocity of 15 m%s and suggestes an @ velocity of 15 m%s. This is


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Figure 2: Some Sample Contours of Pressure

Summary

ou have now successfully meshed up and calculated a basic geometry. ther things you could trywith the data$

'dd a turbulence model

Change the residuals from their default values to much smaller ones

*#tend the problem into D

Tilt the aerofoil and e#amine the prediction of separation

nvestigate the effect of using a much finer grid

This is a tutorial on how to use Fluent to show you the mechanics of running a solution. The flowmodel of the aerofoil produced captures bulk flow effects but for anything more refined you willhave to carefully consider how to model the scenarioA This is not meant to represent goodpractise in CFD but the mechanics of getting the solution to run.

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Hints and Tips on Using Fluent

*very menu in fluent has a +Eelp, button. Click on it and you get "T! of help B thisshould be your first port of call if you are not sure about something.

Check the grid when you first read it in B if it reports errors fi# themA The default viscous model is "aminar flow you probably want to change this to something

else later. :ork out a 9eynolds number to see if the flow is turbulent.

ou do not need to solve the energy e


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Using the Mesh from the Pointwise Geometry

The steps are essentially the same e#cept you only have one boundary condition to set.

9ead the case into Fluent.

File 6J 9ead 6J Case. t may complain about the high aspect ratio of your cells 6 if youcared about the results you ought to do something about this.

Follow the same steps as before with the e#ception of the !olution !etup Task )age.

8odels$ Turn on the !pallart6'llmaras Turbulence model.

8aterials$ !elect the air and hit KCreate%*ditK. n the drop down change the density fromKconstantK to Kideal gasK. "eave the rest of the values at the defaults.

>oundary Conditions$ Eere you set the circular outer edge to be a KFar Field >oundaryKcondition 6 you specify a speed and direction of the far field flow. suggest 8ach 0.L3 @component of 1 and component of 0.05.

!olution Task )age$

nitiali?ation$ had some success with using the Eybrid method 6 7ust hit Knitiali?eK

9un Calculation$ !et the (umber of terations to be 1000 and hit KCalculateK

ou should end up with something like Figure

Figure 3: Solution on Pointwise Mesh

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fluent tutorial 2014

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