Numerical Simulation of Fluid Flows

(BMEGEÁTAG26)

2015. 04. 23.

• András Tomor

• tomor [at] ara.bme.hu

• www.ara.bme.hu/~tomor/CFD/workbench

Main Rules: Whatever you do, do NOT use space and accents in file names! Work in: C:/Work/Neptun_code

Course leaders:

• László Nagy (nagy [at] ara.bme.hu)

•Balász Farkas (farkas [at] ara.bme.hu)

•András Tomor (tomor [at] ara.bme.hu)

•Bence Tóth (tothbence [at] ara.bme.hu)

• Tamás Benedek (benedek [at] ara.bme.hu)

– Transonic airfoil (2D, compressible)

1st And last chapter: Physical modeling and simulation

Run FLUENT

Drag and drop a FLUENT-item from Component Systems toolbox Double click on Setup and run FLUENT ! Choose the 2D simualtion option !

Download of base construction point set http://www.ara.bme.hu/oktatas/tantargy/NEPTUN/BMEGEATAG26/ENGLISH_course/2013-2014-II/ea_lecture/

Right click on basic construction points, select : „Hivatkozás mentése más néven…” , this means „Save target in different name…” (or „Save as”) in hungarian. Save the javascript for example in the: C:/Work/yourneptuncode/orifice/filename.js !Dont use space or any specific characters!

Download the mesh from http://www.ara.bme.hu/oktatas/tantargy/NEPTUN/BMEGEATAM05/2013-2014-II/ea-lecture/FLUENT/

Coose the 4th option from the top to get the mesh

Import Mesh

File/Import/Mesh

Density Based solver for high speed flows

Choose the Density Based Solver

Turbulence model

Turbulenc model: Spalart-Allmaras (This model was originally developed for airfoils)

Materials

Choose the ideal gas model for density calculations (By this the energy equations will be turned on automatically)

Pressure far field

Inelt boundary conditions : Pressure Far field (used specially for high speed flows to define the far field velocity) - Mach-szám: 0.8 - Y komponens: 0

Differencia schemes

Set Second order solvers for all the numerical schemes

Initialization

Solution initialization Standard intializition from: be (from the inlet boundary)

Run Calculation

Numer of iterations: 500

Results (Graphics and Animation in fluent)

Mach-number

Velocity Velocity vectors

Rersults

Static Temperature Total Temperature

Results

Static Pressure Total Pressure

Turbulent viscosity

Text User Interface (TUI)

Click on the Text User Interface, and press Enter, Current Menu going to appear In Fluent all the commands can be reached via TUI

Text User Interface

Type define/parameters into the command line – press enter (its basically the same as clicking on the Define menu what you can find in the main menu bar)

Text User Interface

If you press enter now you going to reach the parameters option Type enable-in-TUI – enter y (or yes) – enter By typing „q”-enter you can go back to the previous menupoint Type q twice (q q) – enter, like this you are back in the main menu

Text User Interface

Go back to define And choose the boundary-conditions option

Text User Interface To publish (set) a parameter for the y component of the velocity Choose pressure-farfield type boundary condition for the inlet (zone id/name [be]) that gonna be the default Keep pressing enter (keep the default settings) till you reach: Use Input Parameter for Y

Component of Flow Direction

Choose: y(es)

Name of parameter: tgalpha

Press enter

Calculation Activities

Now Use the Graphical User Interface!!! Set: Calculation Activities/ Automatically intialize and modify case: check Go to the edit menu: Originial settings/ check Nr. of iterations: 500

Output Parameters

Reports/Forces Forces, Direction: x=1 y=z=0, Zones: sz and ny (suction and pressure sides) Save Output Parameter, Create New … Name: fx (or something you prefer) Define the X component of the force as output parameter.

Output Parameters

Forces, Direction: y=1 x=z=0, Zones: sz and ny Save Output Parameter, Create New … Name: fy (or wahtever you prefere) Close FLUENT!

Runing Fluent in Parameter mode

Double click on parameters

Parametric running And try to cretae the following diagrams

0

2

4

6

8

10

12

0

5000

10000

15000

20000

25000

30000

35000

40000

45000

50000

0 2 4 6 8 10 12 14 16 18

cl/c

d

F [N

]

alpha [°]

Fl Fd cl/cd

Parametric running

Choice of tgalpha is yours

Journal file

Every command can be written in a text file and with this text file we can make all of the commands with one click. An example: - Drag an other FLUENT on the workplace - Download the journal.jou file from the following page:

http://www.ara.bme.hu/~benedek/CFD/workbench/workbench_4th_practice/ - Copy it in the following place: C:\Work\neptun_code\myproject\myproject_files\dp0\FLU-1\Fluent - Start the Fluent Setup

Journal file

- Load in the previous mesh - Read the journal file:

/file/read/journal