fluent-intro 15.0 ws03 multi species postpro

2014 ANSYS, Inc. February 28, 2014 1 Release 15.0

15.0 Release

Introduction to ANSYS Fluent

Workshop 03 Multi-Species Flow and Post-Processing


In this workshop you will analyze the release of heat and combustion gases from a single car with an engine fire in a ventilated parking garage

The simulation will be run steady state assuming the fire has reached a stable developed stage

Simulation Physics & Boundary Conditions Mixture of N2, O2, CO2 and H20 6 m/s exhaust, 0.1 kg/s combustion gases (H2O and CO2) at 1200 K 80 N/m3 momentum source in jets

Introduction

Fresh Air Inlet

velocity_inlet_fresh_air

Jet Fan

fluid_jet_fan

Heat and gas release from fire

mass_flow_inlet_car_fire_source

Air Outlet

pressure_outlet_all_air

Symmetry Plane

symmetry

Introduction Part 1: Long Version Setup Solving Proceed to Part 2.


Important Note

NOTE:

This workshop has been designed to be completed in one of two ways

Please check with your trainer on whether you are to take the short or long option

[Short Option] This workshop can be used just to demonstrate post-processing in CFD-Post

Pre-prepared results files are supplied, so please jump straight to page 35 for post-processing

[Long Option] Follow all the instructions, which will demonstrate how to set up a multi-species simulation of a car fire

Once the model is set up, you can choose to wait for it to converge, or then replace your results with the supplied pre-prepared set



If doing the short version (post-processing only) please jump to page 35 now



Learning Aims:

The first part of this workshop will show how to set up a multi-species problem. The domain will contain a blend of several different gases (nitrogen, oxygen, carbon dioxide, water vapor).

Other topics that will be introduced are:

Including gravitational (buoyancy) effects

Setting a momentum source term to account for a jet fan

Learning Objectives:

To understand how Fluent can be used to simulate mixtures of fluids, and account for buoyancy effects. Note that a multi-species problem like this assumes that the components are mixed at a molecular level (as normally happens with gases). The alternative is a multi-phase problem where there is an identifiable boundary between the components (either droplets / particles / bubbles, or a free-surface). Multi-phase workshops include Workshop 2 (DPM) and Workshop 8 (Tank Flush).

I Objectives (Flow Simulation Part)



Starting Workbench Open Workbench

Start > Programs > ANSYS 15.0 > Workbench 15.0

Drag a Fluent Component System into the project schematic

Rename the system to Garage (RMB on cell A1 to rename the system)



Starting Fluent in Workbench Start Fluent

Double click on the Setup cell to open Fluent Choose 3D and Double Precision under Options and retain the other default

settings (if your computer has 2 or more nodes and parallel licenses are available, you also could start Fluent parallel)



Import the existing mesh file

Under the Fluent File menu select Import > Mesh

Select the file car_and_garage.msh and click OK to import the mesh

To check for any problems in the mesh click Check. There should be no problems reported in the TUI window

Reorder the mesh using Mesh > Reorder > Domain (from the menu)

Reordering the domain can improve the computational performance of the solver by rearranging the nodes, faces and cells in memory.

Retain defaults for the solver

Enable gravity and set z = -9.81 m/s2

Import Mesh and General Setup



Setting Physics (Turbulence) Specify turbulence model

Select Models in the navigation pane

Double click Viscous in the model selection pane. The Viscous Model panel will open

Select k-epsilon (2 eqn) under Model, Realizable under k-epsilon Model and Enhanced Wall Treatment under Near-Wall Treatment

Turbulence modeling, as with all physics modeling, is a complex area. There are many application specific options. The k-epsilon model is a simple but robust model. The documentation provides further guidance on which models to use for specific applications.

Click OK



Setting Physics (Species / Mixture) Specify species model

Double click Species in the model selection pane to open the Species Model panel

In this workshop the products of combustion (heat & gases) will be modeled rather than the reaction itself. You can see in the panel that if it was desired to model fire by including the reactions, there are several combustion models available.

Select Species Transport and click OK Switching on the species model will introduce

new material properties

An information box will appear. Click OK to accept this

This setup will enable the tracking of non-reacting chemical species

The species model requires the definition of a mixture representing the chemical species of interest. The default mixture contains nitrogen, oxygen and water vapour.



Specify mixture

Select Materials in the navigation pane.

Note that under Mixture in the Materials pane the default mixture is listed as containing nitrogen, oxygen and water-vapor.=

Double click mixture-template, this will open the Create/Edit Materials panel with the mixture preselected

Defining Materials (1)



Defining Materials (2) Add a mixture species

In the Create/Edit Materials panel click on Fluent Database

The Fluent Database Materials panel will appear

Select fluid as Material Type

All predefined fluids materials will be listed under Fluent Fluid Materials

Select carbon-dioxide (co2)

Click Copy

Close the Fluent Database Materials panel



Defining Materials (3) Copying carbon-dioxide(co2) from the fluid database has made the species available to

the simulation, now add it to the mixture

In the Materials panel ensure Material Type is set to Mixture

Alongside Mixture Species, click Edit

In the Species panel select co2 from the Available Materials list and select Add

The Selected Species defines the component species of the mixture

The order of the species listed under Selected Species is important. The most abundant species should be listed last

Use the Remove button to Remove n2, followed by the Add button to replace n2 as the last species. Click OK (but dont close the mixture panel yet)



Defining Materials (4) Specify mixture

Modify the existing settings for Thermal Conductivity and Viscosity to be mass-weighted-mixing-law

Click Change/Create to apply the changes



Defining Materials (5) Specify solid material

Select Solid under Material Type. The default solid material is aluminum (al)

Modify aluminum (Name, Chemical Formula & Properties) as shown below

Click Change/Create and choose No for overwriting

Selecting No preserves the original material (aluminum) and adds the new material

Close the Create/Edit Materials panel



Cell Zone Conditions Set Cell Zone Conditions

Select Cell Zone Conditions from the Navigation Pane

Select fluid_jet_fan, then edit

Activate Source Terms

Select the Source Terms tab and click on Edit for Y Momentum

Add 1 source, select Constant and enter a value of -80 (N/m3)

Click OK in both panels


We need to account for the air movement produced by the ceiling jet fan. Here we have done this by adding momentum to the cell zone local to the jet. The advantage of this technique (over using a pair of velocity boundary conditions) is that we preserve the species (smoke) concentration through the fan. If we had used velocity boundary conditions, we would have needed a UDF to find the concentration at the intake to the jet fan and apply that to the jet fan discharge.


Set Boundary Conditions

Select Boundary Conditions from the Navigation Pane

Open velocity_inlet_fresh_air from the Zone list

Apply Momentum and Thermal settings as shown

Continued on next slide.....

Boundary Conditions (air inlet)



Boundary Conditions (air inlet) Set Boundary Conditions.... cont

Apply Species settings as shown

Click OK


The mixture species contains 4 components (h2o, o2, co2, and n2). The most abundant species (n2) was entered last when the mixture was defined. You do not need to enter a mass fraction for n2. It will automatically account for the remaining fraction not used by the first three (in this case 0.77).


Boundary Conditions (air outlet) Set Boundary Conditions

Open pressure_outlet_all_air from the Zone list

For Momentum, in Turbulence set intensity to 5% and viscosity ratio to 5

For Thermal, set the temperature to 293.15 K (as for previous BC)

For Species, set the o2 concentration to 0.23

Click OK


So long as there is only flow out of the domain here, these values for turbulence, temperature and species will not be needed. However during the solution process there may be some inflow though this boundary, and therefore Fluent needs to know what values to apply.


Set Boundary Conditions Open mass_flow_inlet_car_fire_source from the Zone list.

Momentum: Mass Flow Rate to 0.1 kg/s, Normal to Boundary

Turbulence: 5% Turbulent Intensity, Turbulent Viscosity Ratio = 5

Thermal: 1200K

Species: set specify in mole fractions with 0.65 h2o and 0.35 co2

Boundary Conditions (fire source)



Boundary Conditions (walls 1) Set Boundary Conditions

Open walls_outer from the Zone list

Set the temperature to 300 K and click Shell Conduction

Enter the Shell Conduction Model Settings as shown

Click OK in both panels

The Shell Conduction option

enables thin walls to solve for heat

transfer in both the normal and

planar directions without the need to

volume mesh them.


After Shell Conduction is selected, certain fields in the Wall

panel are greyed out and their entries are superseded by the

entries in the Shell Conduction Model Settings Panel.


Boundary Conditions (walls 2) Set Boundary Conditions

Select Copy from the Boundary Conditions Pane

Select walls_outer in the From Boundary Zone list and wall_ceiling and wall_floor in the To Boundary Zones list

Click Copy, click OK in the question dialog box then Close

This will copy all boundary settings from the boundary zone walls_outer to both wall_ceiling and wall_floor



Operating Conditions Set operating conditions

Select Operating Conditions

Apply Specified Operating Density settings as shown

Click OK



Operating Conditions Notes

ANSYS Fluent avoids the problem of round-off error by subtracting the operating pressure (generally a large pressure roughly equal to the average absolute pressure in the flow) from the absolute pressure, and using the result (termed the gauge pressure). The absolute pressure is simply the sum of the operating pressure and the gauge pressure.

Operating temperature is only used when using the Boussinesq density model, so in this case, it has no meaning.

Operating density is also a value for avoiding round-off errors. For simulations where pressure boundary conditions are present it is important to set the value correctly otherwise the pressure at the boundary will be incorrect and may lead to unphysical flow conditions. Here you have to set it to the density for the conditions at the pressure-inlet - a gas at 293.15 K with 23% O2 and 77% N2. You can initialize your flow field with these conditions to get the value for the operating density from the post-processor (e. g. Reports -> Volume Integral). See the Users Guide Natural Convection and Buoyancy-Driven Flows for more details.



Solution Methods Set solution methods

Select Solution Methods from the Navigation Pane

For Pressure-Velocity Scheme, set to Coupled

Under Spatial Discretization set Pressure to Body Force Weighted

The Body Force Weighted scheme is recommended for problems involving large body forces



Solution Controls Set solution controls

Select Solution Controls from the Navigation Pane

Set the values shown below Flow Courant Number = 50 Explicit Relaxation Factors 0.5 (Momentum & Pressure) Density = 1 Body Forces = 1 Turbulent Kinetic Energy = 0.5 Turbulent Dissipation Rate = 0.5 Turbulent Viscosity = 0.7 h2o = 1 o2 = 1 co2 = 1 Energy = 1

Lower Under-Relaxation Factors will reduce the solution change between iterations, leading to more stable convergence though requiring more iterations to reach convergence.



Monitors (1) Set solution monitors

Select Monitors from the Navigation Pane

Click Edit and set the Residual Monitors as shown below

By default ANSYS Fluent will plot residuals to the window and print to the console. The default setting for the convergence criterion is Absolute which means that the solver will continue until all residuals fall below the Absolute Criteria values specified in the Equations box. Switching the Convergence Criterion to none will cause the solver to continue until a maximum number of iterations is reached.

Click OK



Monitors (2) Set surface monitors

Under Surface Monitors, click Create

It is important to ensure that solution variables have converged to sensible stable values. Creating Surface Monitors enables solution values of interest to be monitored on specific surfaces within the domain.

Set the Surface Monitor as shown below and click OK



Monitors (3) Set surface monitors

There are many different types of calculations that can be performed over surfaces listed under Report Type.

Create a second monitor for the integral of the Total Surface Heat Flux on the surface wall_ceiling plotting to window 3 and printing to the console, as shown below



Monitors (3) Notes on monitors

Buoyancy driven flows often show transient behavior. For this reason, the residuals will often oscillate. Because of this, convergence should always be judged by solution variable monitors and flux reports. The residuals will however give an indication of overall convergence behavior and stability.

In cases of an oscillating steady state solution, a common approach is to continue the simulation in transient mode. In many cases the oscillations will reduce significantly after a few time steps.

The use of surface/volume monitors combined with residuals will provide the best overall judge of solution convergence.



Set initialization values Select Solution Initialization and Hybrid Initialization

Hybrid Initialization performs a basic flow simulation (Laplace equation) to set up the initial flow field. Simplified momentum and pressure equations are solved, and so the general flow field can be quickly determined (unlike standard initialization which puts a constant value in each grid cell). By having a more realistic starting point, less work will be needed by the solver to converge the model.

Select More Settings, and for species settings, define the initial o2 concentration to be 0.23, then OK

Only flow and pressure equations are being solved with the Hybrid method, so we need to set a realistic, although constant, value for species

Select Initialize, and watch the TUI window for progress

Solution Initialization



Running the Simulation This simulation will take a long time to compute a converged solution this is not unusual

for such ventilation / natural convection cases. There are natural unsteady features in the flow and the equation set is somewhat stiff to converge.

If you want to run the simulation yourself, set the case to run for 1000 iterations in Run Calculation, and keep an eye on the solution progress

Alternatively, just load the results (data) file supplied with this workshop

File > Import > Data > car_and_garage_1000its.dat.gz

You can reproduce the residual graph (but not the surface monitors) shown below by Monitors > Residuals > Select Residuals then Edit, then press the Plot button



Check Convergence Select Reports from the Navigation Pane and select Fluxes under Reports Click Set Up In the Flux Reports panel select Mass Flow Rate and select the inlet/outlet boundaries (shown below) then click compute Note that the Net Results indicate a good mass balance, but the monitors show the solution is not completely converged. It is likely that there are some unsteady effects present that may necessitate going to a transient (time dependent) simulation. This will be discussed in a later lecture. Note that the energy balance can be checked in a similar way by selecting Total Heat Transfer Rate



Exit Close Fluent

Close ANSYS Fluent by selecting File>Close Fluent

ANSYS Fluent contains basic built in post-processing capabilities which can be used to quickly assess results graphically and numerically during and after the solution

The remainder of this workshop will introduce some features of CFD-Post, which is a powerful, separate post-processing application containing many more advanced features than Fluent



Post-Processing in CFD-Post

Part 2: Post-Processing Colour Images Line Graphs Expressions and Integrals Reports Summary


Learning Aims:

This workshop is designed to teach a range of skills in post-processing Fluent results files using CFD-Post. Topics to be covered include:

Creating surface groups - Creating line graphs

Creating isosurfaces - Creating expressions (CEL)

Creating portable (.cvf) images - Performing integrals

Creating automatic reports - Volume rendering

Learning Objectives:

To understand the ways in which CFD-Post can be used both for high quality images, as well as producing quantitative data from volume/surface integrals, and writing custom functions.

I Objectives (Post-Processing)



Starting CFD-Post If you are doing the long version of this workshop:

Go to the ANSYS Workbench project page Under Component Systems, pick Results and drag onto the desktop Left click in the Solution cell (A3) and without releasing the mouse button, drag the

pointer on to the Solution Cell of the Results system (B2) (see image)

Start CFD-Post by clicking on the Results cell If you are doing the short (post-processing only) version of this workshop: Start CFD-Post from the Start menu:

Start Menu > ANSYS 15.0 > Fluid Dynamics > CFD-Post 15.0 Within CFD-Post, select File > Load Results and pick the supplied file: car_and_garage_1000its.dat.gz OK to the pop-up window



Post-Processing Wall Temperature (1) Add a Location representing a group of surfaces

This lets you group a selection of entities (in this case walls) and apply the same post-processing treatment to all items in the group

Select Location > Surface Group, and enter the name Walls



Post-Processing Wall Temperature (2) Define Location details

The details of the new location will be displayed in the bottom left pane

Select Locations, click on and select all walls EXCEPT wall_car (CTRL click to multiple select)

Click OK in the Location Selector



Apply contour plot to Location

Select the Color tab, click on Mode and select:

Variable: Temperature

Range: Local

Apply

Modify the Legend

Select Default Legend

Right click, Edit

Under Appearance:

Precision 1

Change Scientific

to Fixed

Apply

Post-Processing Wall Temperature (3) This option has allowed us to produce a temperature contour plot of identical colour range on a group of surfaces.



Generate a figure for use later in a report

- Click the Figure icon

- Enter name Figure 1 Wall Temperature

- OK to the Insert Figure panel

Post-Processing Generating a Figure

Remember where this option is (you will be asked to use it several times on subsequent slides). We will be creating several figures as we progress through this workshop. Later on we will demonstrate how to use these figures to automate report-writing.



Post-Processing Section Plane (1) Add a Location representing a section plane

Select Location > Isosurface

In the pop-up window Enter name xzplane and click OK.

Under Geometry tab set Definition Variable to Y

Value to 9 [m]

Click Apply

In the model outline tree,

de-select the Walls option

so only the new slice plane

is visible

Continued on next slide..



Post-Processing Section Plane (2) Under Color set the Variable to Temperature

Under Render disable Lighting, then Apply to display

Generate a new Figure, and name it Figure 2 Temperature Slice



Post-Processing Quick Animation The slice through the model gives us a useful indication of what is happening in the

middle of the domain. A quick animation will transverse this slice through the model so we can see what is happening elsewhere.

Click the Animation button in the top toolbar

Select Quick Animation

Highlight the xzplane object.

Press the Play button , and watch the display

When finished, use the stop button then Close

If required, this animation could be saved to disk in MPEG / AVI formats. The alternative to Quick Animation is Keyframe Animation. To use this you set a series of key animation frames. These might have different objects visible, different points in a transient simulation, or might have the model rotated at a different viewing angle. The animation will progress smoothly between these states.



Post-Processing 3d Isosurface [1] First, change the look of the display:

Hide the plane xzplane previously created by un-ticking in the model tree

Expand the top of the model tree, expanding fluid_main_garage

Double-click on wall_car

Make sure the details box shows (wall_car), if not you will be modifying the wrong object!

For Color select constant, and pick yellow

Apply



Post-Processing 3d Isosurface [2] Add a 3D Isosurface representing gases

Select Location > Isosurfaces

Keep the default name Isosurface 1

Set the Variable to Co2.Mass Fraction and the value to 0.001

Set Color to be constant (in the Color tab) (keep default grey colour), then Apply

Generate a new Figure: Figure 3 CO2 Isosurface



Add 3D streamlines to visualize flow

Hide the isosurface created in the previous step (un-tick in model tree)

Click the Streamline button and keep default name (Streamline 1)

Start From: velocity_inlect_fresh_air

# Points: 100

Under the Color tab set

Mode: Use Plot Variable

Range: Local

Apply

Generate a new Figure of this image

Figure 4 Streamlines

Post-Processing Streamlines



Post-Processing Portable CVF Files [1]

Not only can CFD-Post export regular image formats (jpg /png), but in addition 3D images can be saved. These images have the file extension .cvf

They can be viewed using a free CFD viewer that can be downloaded from the ANSYS website. (Go to www.ansys.com, and search for CFD Post Viewer)

No license is required to use the viewer, so you can install this on any computer (e.g. laptop used for presentations, or ask your client/customer to also download and install a copy).

The 3D image can be viewed using rotate / pan / zoom functionality just as in CFD-Post, and can also be embedded in MS-Powerpoint. However the user cannot modify the image, they cannot add/remove objects from the image, or alter color ranges.

This is a really powerful tool for when you come to present your project work. In many cases a 2D jpeg image cannot explain 3D flow features. However rotating the model live in front of your audience will help convey your findings.




In CFD-Post, click the camera icon:

For Format, select CFD-Viewer State(3D)

Click the folder icon to the right of the filename

Pick the directory you are working in (remember this!)

Save as filename car-streamlines.cvf

Click Save in both windows




Minimise CFD-Post, and use Windows Explorer to browse to the folder used on the last slide

Note how this file (car-streamlines.cvf) is quite small (in this case about 170kB, and therefore easy to email to your client or manager)

Double-click to open this file (it will take a few moments to launch the viewer application)

If you have ANSYS R15.0 installed on your machine, your computer will already have the viewer, and will recognise this file extension. You only need to do a separate installation of CFD-Post Viewer (from the ANSYS website) on machines that do not have Workbench installed.




CFD-Post Viewer will look just like the graphical window of CFD-Post

Use left mouse button to rotate

Middle mouse button (or wheel) to zoom

Right mouse button to translate

Type question mark ? for a list of hotkeys



Post-Processing Volume Rendering Close the standalone viewer and return to CFD-Post

Hide the streamlines plot by un-ticking in model view

Select Volume Rendering, and use name Gas Cloud

Under Geometry, set Co2.Mass Fraction

Keep range as Global, then Apply

To make it easier to see the image, change the screen background colour to white:

Edit > Options > CFD-Post > Viewer

Set Color Type to Solid

Pick White from the color options

OK

This option applies a variable colour and transparency to each grid cell depending on the plot variable. For applications like this involving smoke movement it makes it easy for the eye to assess where the cloud is concentrated.



Post-Processing Quantitative

Until now we have used CFD-Post to create colour images to help interpret the CFD results. Next we will look at some quantitative techniques for extracting numerical data (volume integrals), and producing line graphs. It is also possible to write your own arithmetic expressions for custom post-processing.

Create a line through the model: Hide the Gas Cloud volume rendering Location > Line and keep default name Line 1 Set Method Two Points

From: X=18 Y=3 Z=2 To: X=18 Y=18 Z=2

Set 40 samples along this line Apply

This has created a horizontal line through the model, passing above the front of the car.



Post-Processing Line Graph [1]

Select the Chart Icon from the top Toolbar Keep the Default name Chart 1 then OK

Under General, set the Title to Temperature Profile Under Data Series Set location to Line 1 Under X Axis, set variable to Y Under Y Axis set variable to Temperature Apply



Post-Processing Line Graph [2]

The resulting graph looks like this:

The computation domain exists from 3m < y < 18m

The car (and fire source) is located at

8m < y < 10m

The jet fan is located at 13m < y < 15m

Notice that the peak temperature is located not above the middle of the car (y=9m) but moved some distance to the left (circa y= 6.5 - 8m). This is a direct effect of the air movement from the jet fan.



Post-Processing Volume Integrals

The only source of carbon dioxide (co2) in the model is from the car fire source (the inlet just comprises oxygen and nitrogen). We will perform a volume integral to find out how much co2 is present in the model. Select Calculators tab Select Function Calculator and double click Function: volumeInt (for Volume Integral) Location: fluid_main_garage Variable: Co2.Mass.Fraction Press Calculate

The result is about 0.57m3 of CO2.



Post-Processing Expressions [1a]

It is possible to write your own arithmetic functions for post-processing, making use of the data exported by the solver. The resulting expression may either return a single value (first example, below), or produce a quantity that varies spatially for use in a contour plot / line graph (second example, to follow). Select Expressions tab Right click in the window and select New Enter name PressureDrop then OK Enter the expression exactly as shown below, then Apply The answer is approximately 35Pa If you get any errors look at the next slide now, which will help you understand why



Post-Processing Expressions [1b]

Note how Pressure turns to italics as soon as you type it It is important to make the first letter a capital P For a full list of available variables, right click in this window and select Variables

This is the name of the boundary that you are performing the average function on For a full list of locations, right-click and select Locations Note that to compute the pressure drop, we did not need to add the outlet boundary ...- ave(Pressure)@pressure_outlet_all_air The outlet boundary was set to be a pressure outlet in Fluent with a pressure of 0 Pa. This term would return a zero value try it if you like!

ave returns the average at the location specified by the @ For a list of functions available, right-click in the window and select Functions > CFD-Post



Post-Processing Expressions [2a]

The procedure to create an expression that can be plotted spatially is very similar, there is just one additional step to assign it to a variable As a simple example, lets convert temperature from K to C and plot this on the graph Expressions > (Right click) New > name TemperatureConversion Enter the expression Temperature/1[K] 273.15 then Apply

Note: Initial capitals for Temperature

It will turn to italics if correct Expressions must balance dimensionally

We cannot just enter Temperature 273.15 since Temperature has a unit [K] By dividing by 1 [K] we remove the temperature unit We could instead enter Temperature 273.15[K]

This expression is valid, but would return a value with units [K] which would be misleading



Post-Processing Expressions [2b]

Expressions cannot be plotted directly, they need to be assigned to a Variable

Variables Tab > (Right click) New Enter name TemperatureC

From the pull down list, select the expression TemperatureConversion created on the last slide

Select Apply



Post-Processing Expressions [2c]

Use this new temperature on the Chart created earlier

(Top-Left) select Outline then double-click on Chart 1

Under Y Axis change the variable by clicking on the ... icon

Select this expression TemperatureC

OK then Apply

At the bottom of the screen change from 3D Viewer to Chart Viewer



Post-Processing Expressions [2d]

The graph now shows the result of our expression:



Post-Processing Reports

In the options below the graphic window, select Report Viewer Select Refresh

Review what is shown in the report

window. You can see: Names of the results file Mesh summary List of boundary conditions All the Figures and Charts produced

during this workshop

If you select Publish this will be written out in html format, along with copies of all the results images



State Files and Optional Extra Work

Use File > Save state as... and save to your working directory The state file stores all the post-processing settings you have created. If CFD-Post is used from WB, this is done automatically when closing CFD-Post. If you have done the long version of this workshop, you will recall that we ran for a fixed number of iterations, and wanted to examine the results to help us determine if the model had converged or not. (The residuals were stuck and further iterations would not lower the residuals). It might be be necessary to revisit the model setup, by moving to a transient scheme, or modifying the modeling settings. A useful assessment of convergence is to see if the results of interest remain unchanged as the solver settings are enhanced. The big advantage of having the state file is that if you choose to modify the solver settings and re-run the model, you can quickly reproduce the equivalent post-processing images. Simply load the new results file, then load the state file. Likewise, it is common in project work to have run a series of models to test different operating conditions. This technique will let you generate equivalent images so as to produce a good like-for-like comparison in your presentation / report.



State Files and Optional Extra Work

The Reports feature just demonstrated will let you customise the format of your report

If you have finished this exercise ahead of the rest of the class, try experimenting with

the Report options in the left-hand toolbar

You can choose which objects are visible, add your own company logo, or add lines of text to explain the content of the report



Wrap Up

CFD-Post is a very powerful post-processing tool, and capable of producing high quality images quickly and easily

In this workshop we have shown how to produce contour plots, streamlines, and isosurfaces (as seen in some other workshops for this course)

In addition you have used CFD-Post to perform volume integrals, create line graphs, and to create your own arithmetic expressions for post-processing

3D images can be saved to disk, and viewed in a freeware viewer. This adds much impact to presentations, and can be run on any computer (no license needed)

CFD-Post can also automate the report generation process

Post-processing is best learned by practice. If you have time now, try exploring the other buttons in the interface


fluent-intro 15.0 ws03 multi species postpro

Documents