CFD-Post: Transient Custom Results - Technical Content · PDF fileCFD-Post: Transient Custom Results ... generates a large number of data, which makes the post processing a potentially

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CFD-Post: Transient Custom Results

February/2013

How-to Procedure

Vinicius Strugata Ambrosio

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Contents

Introduction

Problem Definition

Solution

Adapting the Solution

Comments

Version Date Author Reviewed By Comments

1.0 26/02/2013 Vinicius S. Ambrosio

Document History:

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• This document presents a method to generate multiple results along the time steps of a transient simulation using CFD-Post

• All you will need is suitable Project Schematic containing

– A CFD-Post System

– A CCL (CFX Command Language) script, used to export the results

– A Perl script, used to iterates over the time steps

– A transient simulation system (Fluent, CFX) to generate results along the time

Introduction

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• The user needs to post process the results from a transient simulation

• Usually this kind of simulation generates a large number of data, which makes the post processing a potentially difficult task

• It’s required a custom result for each time step

• The transient data is generated by a Fluent simulation solver • CFD Post is able to post process a great variety of data types, including the ones

generated by Fluent (*.cas, *.cas.gz, *.cas.zip *.dat, *.dat.gz, *.dat.zip, *.msh, *.cdat, *.cdat.gz)

• Besides that, CFD-Post is able to execute CCL (CFX Command Language) scripts. It’s possible to embed Perl commands in these scripts, which in turn leverages the power of CCL

Problem Definition

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• The analysis of the results can be executed in the usual way, that is:

I. Decide the variables you are interested to:

a) Example: pressure, velocity, volume fraction, etc …

II. Decide the place in the domain you want to inspect these variables:

a) You can use the domain (all or a part), the boundaries, or

b) You can use Locations: Points, Lines, Planes, etc, placed arbitrarily in the domain

III. Decide the way these variables will be presented/published:

a) 2D Charts, Tables, etc

b) Color Fields, Contour Plots, etc

c) Iso-surfaces, Streamlines, Volume Rendering

IV. Use a CCL Script to:

a) Traverse along the time steps

b) Export the results to a file (image or text file)

The Strategy

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• In order to demonstrate the solution, it’s required a transient result simulation

• The simulation chosen for this demonstration is the “Tank Flush”, from the ANSYS Fluent Training Material

Solution

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• The key to solve this problem is to use a combination of CCL and Perl commands

• This is called “Power Syntax” in the CFD-Post Documentation

• Procedure:

Solution

I. Insert a result you intend to generate for each time step. Example: A figure for a particular time step

1) Export via CCL the figure to the disk

2) To do so, the easiest way is record a session while executing manually this task

3) Click on Session → New Session. Set the file name for the session.

4) Click on Session → Start Recording.

5) Click on File → Save Picture …

a) Change the setting if required and click on “Save”

6) Click on Session → Stop Recording.

CCL Session File generated

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• Procedure (cont):

I. Use the Command Editor to combine the CCL script that you generated in the previous step and the Perl command to iterates over the time steps

Solution

1) Click on Tools → Command Editor

2) Paste the contents of the CCL script generated in this editor.

3) Now inserts the below Perl commands (more details in the following slides)

CCL Session File is executed for each time

step

Gets the Time Steps

Iterates over the Time

Steps

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Solution

4) Click on Process to execute the commands

5) The desired files will be generated in the specified folder

a) Please notice that the time step is part of the filename.

• Procedure (cont):

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• This is the complete script, provided for your convenience

Solution

# Session file

# CFX-14.5 build 2012.09.19-21.47

# Description:

# The goal of this script is to generate output results for all timesteps available

# Data: 26/02/2013

# Version: 1.0.0

COMMAND FILE:

CFX Post Version = 14.5

END

# Gets the timesteps

! $timestepList = getValue("DATA READER", "Timestep List");

! @timesteps = split(/, /, $timestepList );

! $nTimesteps = @timesteps;

! $userFilesPath = “C:/Temp/";

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• This is the complete script, provided for your convenience (cont)

Solution

! for $timeStep (@timesteps) {

> load timestep=$timeStep

! $filename = $userFilesPath . "Figure-$timeStep.png";

HARDCOPY:

Antialiasing = On

Hardcopy Filename = $filename

Hardcopy Format = png

Hardcopy Tolerance = 0.0001

Image Height = 600

Image Scale = 100

Image Width = 600

JPEG Image Quality = 80

Paper Orientation = Landscape

Paper Size = Letter

Print Line Width = 1

Print Quality = High

Screen Capture = Off

Use Screen Size = On

White Background = Off

END

>print

!}

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• The presented method is generic enough to outputs any kind of data generated by CFD-Post

Adapting the Solution

• For example, let’s suppose you want to export the data along a Line

• All you need to do is:

– Obtain the CCL script required to export the data (using the session recorder shown earlier)

– Modify the script so that it can be used alongside the Perl script (changing the filename, etc)

The data in this line

can be exported

The resulting set of CSV files,

one for each time step

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• This is the complete script, provided for your convenience

Adapting the Solution

# Session file

# CFX-14.5 build 2012.09.19-21.47

# Description:

# The goal of this script is to generate output results for all timesteps available

# Data: 26/02/2013

# Version: 1.0.0

COMMAND FILE:

CFX Post Version = 14.5

END

# Gets the timesteps

! $timestepList = getValue("DATA READER", "Timestep List");

! @timesteps = split(/, /, $timestepList );

! $nTimesteps = @timesteps;

! $userFilesPath = “C:/Temp/";

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• This is the complete script, provided for your convenience (cont)

Adapting the Solution

! for $timeStep (@timesteps) {

> load timestep=$timeStep

! $filename = $userFilesPath . "Export-Line1-$timeStep.csv";

EXPORT:

ANSYS Export Data = Element Heat Flux

ANSYS File Format = ANSYS

ANSYS Reference Temperature = 0.0 [K]

ANSYS Specify Reference Temperature = Off

ANSYS Supplemental HTC = 0.0 [W m^-2 K^-1]

Additional Variable List =

BC Profile Type = Inlet Velocity

Export Connectivity = Off

Export Coord Frame = Global

Export File = $filename

Export Geometry = On

Export Location Aliases =

Export Node Numbers = Off

Export Null Data = On

Export Type = Generic

Export Units System = Current

Export Variable Type = Current

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• This is the complete script, provided for your convenience (cont)

Adapting the Solution

External Export Data = None

Include File Information = Off

Include Header = On

Location = ambient

Location List = /LINE:Line 1

Null Token = null

Overwrite = On

Precision = 8

Separator = ", "

Spatial Variables = X,Y,Z

Variable List = Water.Volume Fraction

Vector Brackets = ()

Vector Display = Scalar

END

>export

!}

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• This procedure is not necessary if you just want to export a set of images from a transient simulation result

• To do that, just proceed with the animation configuration and mark the option “Save Frames as Image Files”, as shown below. The images and the movie will be generated when you click on the “Play” button

Comments

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Contacts

• If you need help

• https://esss.zendesk.com/home