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This presentation introduces you to the many new improvements available in ANSYS FLUENT 12.0. We are

very excited about integration into ANSYS Workbench, with all the benefits it brings, and the new

enhancements available for in-cylinder combustion, multiphase, and HPC. I hope you find these slides and

the accompanying notes informative. Please see the ANSYS FLUENT 12.0 documentation for additional

information about new features.

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ANSYS is the single largest provider of CFD technology in the world and has the broadest CFD product line,

with general purpose and application-oriented CFD offerings. We also have the largest CFD development

teams and the most CFD experience. If you read our ANSYS Advantage magazine, you may have seen the

nice overview of our CFD products published recently. ANSYS’s suite of fluid dynamics products includes two

general purpose fluid dynamics solvers: ANSYS FLUENT and ANSYS CFX, as well as a number of specialty

purpose fluid dynamics products such as ANSYS POLYFLOW for polymer processing, FLUENT for CATIS

V5, a turbo-suite, and others.

This presentation focuses on ANSYS FLUENT 12.0.

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This slide illustrates the status of ANSYS Fluid Dynamics at 12.0. This is a major integration step for FLUENT

and CFX and expansion of the ANSYS Workbench! The same CAD connection can be used, whether

running CFX or FLUENT. DesignModeler (DM) and the new ANSYS Meshing Platform (AMP) are the

common geometry/grid engines, and combine the capabilities of previous tools. CFD-Post is the common

post-processor.

Integration under ANSYS Workbench has other benefits in addition to providing consolidated tools for

FLUENT and CFX under a single platform such as flexible workflows and the ability to connect to ANSYS

mechanical, for 1-way FSI analysis, and other simulation tools. A major benefit is the parameter management

and system wide updates that can be done using Workbench. For example, with previous versions of

FLUENT, if you were modeling a pipe, you created a pipe geometry, meshed it, set-up the FLUENT case,

solved the simulation, and did your post-processing. If you needed to look at a different pipe diameter and

length, you would have to manually create the modified geometry, mesh it, set-up a new FLUENT case, re-

solve the simulation, and perform essentially the same post-processing. Using FLUENT under ANSYS

Workbench with integrated applications, to make this same kind of change after solving the first pipe, you can

simply go back to DesignModeler, change the appropriate pipe dimension and click update. The geometry

change is then automatically pushed through the entire system, from meshing through post-processing where

you can see the modified geometry in CFD-Post with the previously created post-processing objects updated

for the new solution.

This slide contains a screen shot of the ANSYS Workbench user interface with 2 FLUENT Fluid Flow and a

results system in the project schematic. You can see that parameters are connected to the FLUENT systems

and that results from both systems will be compared in a single results system. In the project schematic, you

can also see how all ANSYS applications are integrated. The schematic facilitates project management and

allows for the easy reuse and sharing of workflows. Integration under Workbench allows permits workflows to

be automated and system-wide parameters to be defined and managed.

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At release 12.0, the ANSYS CFD system is fully hosted within the Workbench platform. This gives access to the industry leading ANSYS CAD connections , supporting connections to all major CAD systems, either by direct/live 2-way connections to the CAD packages, or by data file transfer. Geometric dimensions and parameters from the CAD system are preserved inside Workbench, and are available for parametric analysis.

As a CFD practitioner you require a range of meshing tools. ANSYS CFD 12.0 gives access to the full range of meshing methods in the ANSYS Meshing Platform. Significant advances in most meshing methods have been made for release 12.0, including combining hybrid and hex meshing methods from FLUENT, ICEM CFD and ANSYS structural meshing methods. It is possible to create meshes quickly for initial design flow simulations, as well as high-end meshes required to get the most accurate CFD simulation possible.

The CFD workflow is managed within Workbench for both the FLUENT and CFX solvers, as well as access outside of Workbench in standalone mode and for embedding in your customer design system. The full range of possibilities exists. The FLUENT solver user interface has received a major step forward in a single window interface paradigm, similar to other applications in Workbench such as CFX. The CFX solver user interface can now be customized like never before, making it possible for you to easily manage the setup of complex flow simulations with a minimum number of inputs, increasing the quality control for your process and decreasing the setup time required.

Finally, we are excited to introduce our common CFD post processing application, CFD Post, which is the result of combining post processing technologies from both FLUENT and CFX, building upon the former CFX-Post application. Workbench provides a framework for all of the relevant CFD applications within a single user environment, with built-in intelligence and workflow recording mechanisms to make CFD process automation possible, even simple, to achieve.

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Our new ANSYS CFD-Post application works with all ANSYS CFD applications. It is a full-featured qualitative and quantitative CFD post processor with all of the functions you expect and need, and then some, all within a modern and flexible user interface. CFD Post can load data efficiently and quickly from ANSYS CFX, ANSYS FLUENT, ANSYS Polyflow and even ANSYS solid mechanics solvers, steady state or transient. All mesh styles are supported including all of the required CFD element types, polyhedral meshes, hanging node meshes and non-conformal meshes. CFD Post works in a memory efficient manner with on-demand data loading, for maximal use of the available computing resources.

It is hard to succinctly summarize all of the specific improvements that have been made for CFD Post at release 12.0. Some of the highlights include:

1. New functions that support advanced comparison of CFD simulations, either on the same or different meshes. You can easily load and compare multiple simulations, generating graphical visualizations of the differences, as well as direct and derived quantitative differences.

2. Major improvements have been made in the area of transient post processing, in terms of efficient handling of transient data sets, and support for the full range of transient CFD simulations including moving/deforming meshes and transient remeshing.

3. Many low level functions and features have been developed and expanded for release 12.0. Histograms are now supported. Fast Fourier Transforms are built into the x-y charting functions for frequency-domain data representation. Automated flow feature detection algorithms have been developed, for example to locate and visualize swirl strength and vortex core locations.

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Please note that CFD-Post will complement (as opposed to fully replace) the post-

processing functionality available in FLUENT. You will still be able to pause your simulation

to check the progress with FLUENT’s integrated post-processing. When you need more

advanced post-processing, CFD-Post will be available. On this slide I would like to call out

some of the specific benefits of CFD-Post 12 for FLUENT users.). CFD-Post 12 will be able

to read native FLUENT case and data files and you can launch CFD-Post directly from the

FLUENT interface in the stand-alone version of FLUENT, assuming you have CFD-Post

installed and have an appropriate license. Please note that CFD-Post is not a solver and

does not include information about all of the models used in FLUENT. Additionally, in

FLUENT, some variables are not stored in case and data files. Instead, they are calculated

on the fly for post-processing using FLUENT’s models. To make these extra variables

available to CFD-Post for post-processing, you can add them to your standard FLUENT

case and data files using the panel accessed under File Data File Quantities. There is

also an option in FLUENT 12 under the file menu to export lightweight CFD-Post

compatible files that contain just the variables of interest and are smaller than traditional

FLUENT case and data files. Please note that these files are NOT FLUENT restart files.

In addition to more modern post-processing options in general, CFD Post provides

advanced functionality that will be especially welcomed by FLUENT users. CFD Post

provides you with more efficient transient post-processing capabilities, the ability to

compare different datasets within the same session, and the ability to have HTML reports

generated automatically. You will be able to continue to use FLUENT post-processing and

you will also have the option to use CFD Post to access to more advanced post-processing

capabilities.

CFD-Post will also allow you to export files to be used with a very cool 3D Viewer. How often do you send an

image to your customer or colleague only to be told nice, but I really wanted to see this from another angle or

position? With CFD-Post 3D viewer files and the very cool 3D Viewer, you will be able to send one set of files.

These files and the plug-in viewer will allow you to put interactive images in your PowerPoint presentations. .

A screen shot from an active viewer image and the help panel is shown on this slide. You can rotate, pan,

translate and zoom in on the image. You can turn the lights on and off. You can also reset the image. We are

very excited about the information you will be able to convey during your presentations using this exciting tool.

Notes: You need a PowerPoint plug-in that lets you insert web pages for this to work.

Once you have the plug-in, when you have the viewer sub-panel selected use the following controls:

?: help (shown in screen shot)

L: toggle lights

R: reset

S: toggle remove surfaces when changing view

Left Mouse Button: rotate

Middle Mouse Button: zoom

Right Mouse Button: pan

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Now that we have covered an overview of ANSYS CFD Products, I would like to focus a bit more on ANSYS

FLUENT.

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In ANSYS FLUENT 12, we have completed developments in all of these areas and

more. It is impossible for to cover all of the over 300 individual new features in

FLUENT 12 in a reasonable amount of time. However, I will try to discuss the most

significant ones ...

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The first time you open FLUENT 12, you will notice that FLUENT has a new interface. We

have re-factored the user interface to make it more modern with a “Workbench-like” look

and feel. The screen layout shown here is of FLUENT when a case is first read in and the

models task page is chosen. This new interface is contained in a single window. There is a

navigation page, task pages, graphics windows, and the text user interface. However, if you

prefer, there is an option in the new FLUENT Launcher to start with detached graphics

windows1 or you can detach them on the fly using an option in the View menu.

Please note that the traditional FLUENT workflow is maintained, since the menus are still

accessible.

This new interface is the one you will see when launching FLUENT stand-alone and from

within Workbench.

Notes: 1This is the Embed Graphics Windows check box. Uncheck for detached graphics

windows. When starting from the command prompt, you need to add –fgw to Free the

Graphics Windows and to suppress the automatic mesh display, add –nm (No Mesh).

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FLUENT 12 is part of ANSYS Workbench. This integration allows you to access geometry, meshing, FLUENT

and advanced post-processing from within a single project management environment. Workbench integration

also provides support for parameter management. The ability to use parameters is included in FLUENT.

Option for parameters appear in the boundary condition and quantitative post-processing panels such as the

panels shown on this slide. There is also a panel for managing your parameters. A single input parameter can

be associated with several boundaries in a case, such as outlet conditions of a manifold, and multiple input

parameters can be defined for a single case. All parameters are accessible from the parameter manager

panel within FLUENT where you are able to manually change the value of these parameters your self. You

are also able to automate a series of runs using these parameters inside Workbench. Output parameters can

be linked to a single, quantitative value within FLUENT for example, surface and volume integrals and

averages. Within FLUENT, you are also able to report all defined output parameters at once to the text-user

interface. Output parameter reports can also to be managed by Workbench. In this way, parameters are

useful both with and without Workbench.

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For all of our solvers, in FLUENT 12 you are able to specify your own initialization and start-up routines using

automatically executed user specified solution strategies available in the Automatic Solution Initialization and

Case Modification option available from the Calculation Activities task page. You are able to specify your

initialization method on the Initialization tab and use any text command on the Case Modification tab. This

option helps replace the need to use some simple journal files, especially for cases where a prescribed

routine is used (start with 1st order, switch to 2nd order, turn on reactions, etc..) Any TUI command is accepted.

Solution strategy also allows solver-based mesh changes and start-up procedures to be used within

Workbench when updating a system.

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Internal combustion engines are a major focus area for ANSYS FLUENT 12.0, with IC specific development in

areas such as meshing, reporting, DPM, and combustion that will be outlined on the next few slides.

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In the meshing area for IC, we have ensured that FLUENT’s activate/deactivate zones functionality is fully

available in parallel in FLUENT 12. Activate/deactivate zones is used during simulations where some parts of

the domain become irrelevant to the simulation and then are needed again. In the example shown on this

slide, the intake port is not required when the intake valve closes and is thus deactivated.

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Dynamic mesh events are used in many applications to change FLUENT’s settings. For instance, they can

be used to change the time step size during a simulation. Previous versions of FLUENT only permitted a

limited number of FLUENT settings to be manipulated using dynamic mesh events. FLUENT 12 expands this

functionality to include any TUI command. In the example shown here, two events are set up using text

commands to switch between smoothing and layering for a two stroke engine simulation.

This mesh motion animation shows the mesh motion due to these two events. As you can see, smoothing is

used to maintain the same number of layers as the piston moves away from Top Dead Center, or TDC. As

the piston moves further away from TDC, smoothing is turned off and layering is turned on to add layers. The

opposite occurs when the piston moves back from Bottom Dead Center to Top Dead Center. This automatic

switches are achieved by the two events shown in the panels.

Notes:

List of IC-related meshing features not included above:

Layering with non-constant layer height: Allows to specify the height of new cell layers via UDF (based on

time/CA) in addition to a constant height which is currently available.

Skewness report for IC cases: The max skewness should be reported only for the zones where remeshing

took place.

Ability to Set Max Flow Time: Provide the ability to set the max flow time in the TUI.

MDM Default for Layering Collapse Factor Change: The default collapse factor for moving/deforming mesh

has been changed to 0.2

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Also, for IC, we have taken a UDF that calculates some IC specific values and incorporated it directly in

FLUENT 12. This allows commonly used IC reporting values to be calculated automatically directly within the

solver. You will be able to find this panel by clicking Output Controls… in the In-Cylinder Settings panel

available from the dynamic mesh task page.

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We have also completed some development in the DPM area specifically for IC You will be able to

conveniently use crank angle as the time unit when defining injections. We have also added vaporization

laws specific for IC.

The combustion area was the focus for a lot of IC-related items in FLUENT 12 and also an area with

especially active coordination between the FLUENT and CFX development teams. The “Extended

Coherent Flamelet Model" is available in FLUENT 12 (and CFX 12). This model uses a different way of

closing the flame speed for the premixed and partially premixed model. The ECFM uses a transport

equation to track flame area density which corresponds to the wrinkling of a laminar flame front on a

subgrid scale. The turbulent flame speed term in the reaction progress equation is then the laminar flame

speed multiplied by the subgrid flame area. This model is most widely used in IC engines, however it

belongs to a family of two equation flamelet models which are commonly used in general combustion

problems found in furnaces and gas turbines.

We have also added a model for exhaust gas recirculation in FLUENT 12 (and CFX 12). This inert model

is a modification of our PDF combustion models (partially premixed and non-premixed) which tracks a

non reacting stream which affects the fluid properties (mixture density, specific heat, etc.). This will allow

you to model both exhaust gas recirculation (EGR) and dilution in an engine without adding an additional

dimension to the PDF table. The main assumption in this model is that the composition of the inert

stream does not change, so the inert stream and the PDF table can be treated separately.

Finally, you will have access to a UDF hook for the ignition model that allows you to use custom ignition

models via UDF.

Notes: Features not included in the slides:

Add time exponent parameter to spark GUI

Zimont turbulent flame speed wall damping: Provide the ability to model flame speed damping effects

near the wall. Partially Premixed Model Compatible with Empirical Fuels

Allow the user to be able to use the partially premixed model with empirical fuel and empirical secondary

stream options. Add the molecular weight of the fuel and secondary stream to the GUI and TUI.

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Moving on to some more general ANSYS FLUENT 12 features. Starting with core numerics… In my opinion,

the three components of numerics are accuracy, robustness, and efficiency. As always, we continue the

FLUENT and ANSYS tradition of improvements in all 3 of these areas .

We continue to improve the accuracy and robustness of all of our solvers. One feature that I would like to

emphasize is a new option that is available in the text user interface1: first-to-higher-order blending. Everyone

has had a case that converges well in first-order but then diverges or oscillates with a switch to second-order.

This option will provide a better than first order solution if second order will not converge. This option will be

available for the pressure-based and density-based solvers. On the right side of this slide you can see first-to-

second order blending at work in a supersonic projectile case. In the plot of average static temperature vs.

iteration, you can see 1st order nicely flatten out and the second-order solution oscillating. When blending is

turned-on, the solution once again flattens out. Please do use 1st to higher order blending on cases with this

behavior to achieve a better than 1st order accurate solution that converges nicely.

Notes: 1TUI command: solve set numerics

When this option is selected it will impact all flow and scalar equations. In DBNS it is applied directly to the

reconstruction gradients, while in PBNS is applied to what is called secondary gradients.

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We also improved the transient efficiency of all of our solvers. When we introduced NITA in FLUENT 6.2,

there were some models that were incompatible and continue to be incompatible. To improve the transient

efficiency of those models, there is an option on the Run Calculation task page to extrapolate variables from

previous time steps to get an initial solution for the current time step. Variable extrapolation is also available

for NITA compatible models when they are run iteratively. Variable extrapolation was used for the simple

axial compressor example shown on this slide and compared to the same case without extrapolation. As you

can see in the chart on the top, the force integration vs. time curves are exactly aligned, indicating full

convergence and no loss of accuracy due to variable extrapolation. The chart on the bottom shows the force

integration vs. iteration. As you can see, the case that used variable extrapolation completed in 9.457

iterations, 22% less than the 12,100 iteration required for the case without variable extrapolation. I encourage

you to try using variable extrapolation to improve the efficiency of your transient cases.

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In FLUENT 12, a lot of development focused on improving the robustness of the density-based solver. For

example, solution steering for the density-based implicit solver. Solution steering is intended for use when you

would like to have a 2nd order solution and convergence is difficult. It provides a framework for converging a

solution with the density-based implicit solver with minimum user interaction and tweaking. The usual

procedure for difficult to converge cases is to run the simulation using 1st order discretization for some time

before switching to 2nd order or use FMG initialization and, possibly, 1st order discretization before proceeding

with 2nd order discretization. Solution steering will automate these initial steps. The default settings for solution

steering are those which will successfully converge most cases in the user-selected flow regime. They are

usually not the optimum solution settings for these cases. Because solution steering settings will be general,

they are not expected to outperform the convergence rates that experienced users are able to achieve by

using case specific solution strategies. However, they do automate the start-up stages so that you do not

have to wait to manually change the case settings before calculating the final solution. The interface for

solution steering is shown here.

Notes: 1This feature is not available for cases with MDM.

Flow Types: Note: There is no exact Mach number cut-off for these regions, therefore, the above Mach

number ranges are just a simple guideline to help you select a flow type.

Incompressible (if the flow is incompressible , i.e. density is constant)

Subsonic (if the flow is compressible and M 0.75)

Transonic (if the flow is compressible and 0.65 M 1.2)

Supersonic (if the flow is compressible and 1.10 M 2.5)

Hypersonic (if the flow is compressible and 2.0 M)

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In this turbine stage example, we can see solution steering at work. This example uses the transonic

schedule. On the right, we see the blending factor history on the top. During the first solution stage, we ramp

up the blending factor until we are at second-order. In stage 2, we ramp up the Courant number from 5 to 200

as seen in the middle plot. The bottom plot shows the convergence history, including the termination level for

the Courant number. When the residuals reach this level, we stop updating the Courant number. Using

solution steering will improve convergence and convergence speed for many cases.

Other solver development items not included in the slides:

We have improved adaptive time stepping in FLUENT 12. You have the ability to undo a timestep if the

solution is not converged in the user-specified maximum number of iterations per timestep or if the truncation

is error is greater than the user-specified value. If neither condition can be met, FLUENT will make 5 attempts

before proceeding to the next time step. This is not available for cases with MDM.

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There are several enhancements for parallel file handling that I would like to discuss. Let us start with the file

read and write enhancements. In FLUENT 12, we improved the case and data file read/write times when

using standard file I/O. For relatively large cases, over 10 million cells, the improvement could be up to 10

times faster than FLUENT 6.3. The plots on this slide show some sample file I/O results for FL5L3, a 10

million standard benchmark case. The improvements for data file write for this case range from FLUENT 12

being 5 times faster on 128 processors to and 9 times faster on 8 processors than FLUENT 6.3 as shown on

the upper right. Data file read times range from 6 times faster on 128 processors to an impressive 13 times

faster on 8 processors when comparing FLUENT 12 to FLUENT 6.3 for this case as shown in the lower right.

In FLUENT 12, case files write times are 3 times faster than 6.3 on 4 and 8 processors for this case as shown

in lower left.

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One parallel feature that we are very excited about is the ability to read and write DATA files using truly

parallel I/O. In versions prior to FLUENT 6.3, all file I/O was done in a purely serial fashion where each node

sends the data to the next node in line. Eventually, all of the data reaches node 0 and is passed to the host

node and is written to the file. In FLUENT 6.3, we improved this process by collecting and grouping the data

from the nodes as they are passed to node 0. However, passing the data to the host node and writing it to the

file remains a serial process. This is the standard file I/O process that has been improved and that I discussed

in the previous slide. In FLUENT 12, all nodes have direct access to the file system through an MPI I/O layer

when reading and writing DATA files using a new .pdat format.

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Truly parallel data file I/O does require a parallel file system to be used. The parallel file systems supported

for FLUENT 12 are listed here.

We have seen some impressive speed-ups of data file read/write times using truly parallel I/O for data files.

Results from a 111 million cell test case are shown here. In these charts, we are comparing the times to read

and write .pdat files using parallel I/O with times required to read and write .dat files using the standard I/O

process (FLUENT 6.3 method shown on the previous slide) also improved in FLUENT 12 as I showed you

previously. You can see that truly parallel I/O is nearly twice as fast for this case when reading data files using

an Opteron Infiniband cluster with IBM/GPFS. Opteron Inifiniband cluster with HP/SFS with Infiniband fabric in

the file systems shows is a dramatic 6 times faster when reading the data files than standard file I/O for this

case. On both systems, speed-ups for writing data files are also attained. The standard I/O times shown are

also for FLUENT 12.0. So, the speed-ups cited are in addition to the improvements attained for standard I/O

in FLUENT 12.0.

Notes:

Notes: Truly parallel I/O is NOT available for CASE files. Case files continue to use the standard I/O method

when reading and writing in parallel. To use parallel I/O for DATA files, all that is required is that you write the

data file using a .pdat extension (instead of .dat). If you need to switch back to a .dat file, just read the .pdat

file into the parallel version of FLUENT and write a .dat file. You can read .pdat files on a different number of

processors than you wrote them, but you must use the parallel version of FLUENT (you can use –t1).

Does not work on NFS mounts

Some limitations on compatibility across platforms

Files are uncompressed and are larger

Support for Panasas, PVFS2, HP/SFS, IBM/GPFS

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Like truly parallel I/O for data files, the next few features I will discuss really focus on developments for large

cases. Auto-partitioning, i.e. , reading a case into a parallel solver without pre-partitioning, may take more

than 50% or more of overall case reading time. In FLUENT 12.0, this process is significantly sped-up due to

the implementation of a fast auto-partitioner which also reduces the peak memory required for auto-

partitioning. In the examples on this slide, with the fast auto-partitioner in FLUENT 12.0, auto-partitioning a 10

million cell benchmark case is 17 times faster on a 12-way parallel run as seen in the top plot on the right and

auto-partitioning a 256 million cell benchmark case is 1500 times faster on a 512-way parallel run as seen in

the bottom plot on the right. This improvement will be scalable with increasing number of nodes, while the old

method is not.

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Many of our customers are running bigger problems with more and more cells. There is a desire to run

cases with over 1 billion cells. In previous version of FLUENT, the limit was ~700 million cells total. In

FLUENT 12, in the Opteron/EM64t lnamd 64bit version of FLUENT, 64-bit indexing permits ~700 million

cells per processor or core with no performance penalty seen during iterations. This allows larger

meshes to be used in FLUENT. This is especially important for external aerodynamic simulations like the

examples shown here. You may have seen our recent press release “ANSYS Breaks 1 Billion Cell

Barrier” in which FLUENT was used during the first commercial simulation of more than 1 billion

computational cells using software from ANSYS, performed to investigate the aerodynamics of an

America’s Cup yacht.

Notes:

Press Release: http://phx.corporate-ir.net/phoenix.zhtml?c=118715&p=irol-

newsArticle&ID=1227094&highlight=

Press Release Images: http://www.ansys.com/special/news-images/2008/billion-cell-11-17-imagesheet-

08.htm

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Significant improvements in scaling, especially for large clusters, are available in FLUENT 12.0. A plot

showing scaling improvements for a 111 million cell benchmark case is shown in the plot on this slide.

You can see that this case scales nearly ideally all the way to 1024 processors and at 78% of ideal at

2048 processors. In previous versions of FLUENT, performance leveled out at 256 processors for this

case with decreased efficiency seen beyond 256 processors.

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We would also like to assure you that the new dual and quad core processors from Intel and AMD are

well-suited for FLUENT 12. You can see scaling for 2 of our benchmark cases on a dual CPU with

quadcores in the plot on the right. Tuning in FLUENT 12.0 has been demonstrated to provide up to 20%

better performance on the multi-core chips than previous versions of FLUENT. Both Intel and AMD

processors show similar performance improvements.

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Dynamic load balancing provides better scalability of cases with imbalanced physical or geometrical

models. The implementation is based on considering weights from these models scaled by CPU time

usage. In FLUENT 12, specifically, we improved dynamic load balancing for the DPM and VOF models,

ISAT, and simulations containing different cell types (number of faces per cell) and solid zones. On top

of this, machine load distribution can also be specified, which already exists in older version of

FLUENT. The load balancing can also be coupled to dynamic load balancing for optimal scalability of

cases involving multiple physical models.

In the simple example shown on this slide, a DPM case is partitioned into 2 domains with and without

load balancing and the iterations are timed. When the domain is partitioned into two sub-domains

without considering the weight of particles, as shown in the top image, a huge load imbalance results

because the second partition will not share the load of particle tracking. When the particle tracking time

is taken into the consideration the partitions change, as shown in the bottom image. Here, the weights

used for partitioning are based on the time used by each physical model. The resulting load is better

balanced. For this specific case, the time for one iteration is decreased from 13.2 seconds to 7.8

seconds.

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I will just mention 2 of the improvements made in the meshing are here.

The memory usage when converting your meshes to polyhedras has been reduced. In fact, the peak memory

usage during polyhedra conversion has been reduced to about 55% in comparison to 6.3 for the test cases we

have run.

In response to several long-standing customer requests, we have also added the ability to do anisotropic

adaption at boundaries in FLUENT 12. This allows you to split the cells near boundaries into halves instead of

eighths, providing the required mesh resolution without unreasonably increasing the cell count. An example is

shown here. In this case, anisotropic adaption was used to refine the boundary layer for a F1 car. The BL

contains 5 prism layers. The bottom image on the right shows that each one has been split. Being able to do

anisotropic adaption for cases like this will allow you to achieve the required y+ values for a simulation with a

smaller increase in cell count than adapting isotropically.

Notes: Other mesh features not included in the slides

Add option to preserve zone names during zone fusion (TUI only)

More robust creation of periodic for both simply connected domain and multiply connected domains.

Many-to-many nonconformals interfaces with mixed zones

Auto-Detect of Periodic Shift (Angle/Offset) for Non-Conformal Interfaces: Provide the ability for FLUENT to

automatically detect the periodic shift (rotational angle/ translational offset) for mesh interfaces and display

this in the Mesh Interface Panel.

Improved MDM : steady-state deformations – allow the user to do additional remeshing after the mesh moves

User Defined Node Memory: Allow the user to enable and set user defined memory at grid nodes.

Dynamic mesh GUI enhancements

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As previously mentioned, you can couple FLUENT and ANSYS under Workbench for one-way FSI

calculations. I would like to let you know that we have also taken a UDF popular among our customers for

doing one-way FSI using FLUENT and common FEA codes and directly implemented it into FLUENT 12.

This feature allows you to do one-way couplings between FLUENT and ANSYS outside of Workbench and

with several 3rd party FEA codes – ABAQUS, I-deas, NASTRAN, and PATRAN.

You are able to map structural and thermal loads on surfaces and temperatures in volumes from FLUENT to

FEA meshes using this functionality.

To accomplish this coupling, read in your FEA mesh, taking care to select the correct length unit. Then

choose what kind of data you would like to interpolate from the FLUENT simulation onto the FEA mesh and

the specific FLUENT zones you would like to use in the interpolation. Finally, set the output file options and

click Write. FLUENT will do the interpolation from the FLUENT mesh to the FEA mesh and write the file.

There is also an option to display the imported FEA mesh together with the FLUENT mesh. This option helps

you ensure that you are using the correct files and interpolating the correct zones.

With FLUENT 12.0, the ability to perform two-way FSI calculations using MpCCI and a number of FEA

software packages, including ANSYS, is still available.

34

For boundary conditions, we have added several new features for inlet boundary conditions in particular.

First, when using pressure and mass flow inlets in FLUENT 12, you are able to specify swirl component at

inlets for both the density and pressure-based solvers. This features provides more robust convergence for

turbomachinery cases with high levels of inlet swirl. For the density-based solver, you can specify the inlet

condition all in the relative or absolute frame of reference, making the set-up of these inlets more straight-

forward.

Notes:

Features not included in these slides:

Pressure Inlets: make the pressure-extrapolation method available via TUI (DB solver)

Massflow Inlet: Extrapolate T when flow is leaving a boundary for PBNS

Mass flow inlet: UDF hookup for mass flow rate (PB and DB solvers)

35

You are also now able to use mass flow inlets as outflow boundaries with the density-based solver in

FLUENT 12. You are able to specify that a mass flow inlet is an outflow boundary by using the Outward

Normals Direction Vector or by using flow components that point away from the boundary when using the

Direction Vector flow specification method. With either of these methods, the mass flow boundary then

operates as an outflow, pumping flow out of the domain with the rate specified in the Mass Flow

Specification Method. When using a mass flow inlet as an outflow boundary with either the pressure-

based or density-based solvers, if the mass flow rate is specified, the fluxes on the boundary are allowed

to vary to preserve the flow profile out of the domain. At convergence, the total mass flow rate should

match the specified value. If a constant mass flux is needed rather than the default variable fluxes to

preserve the boundary profiles, you are able to use a text command to turn off the profile preservation1.

Notes: 1Define /boundary-conditions/bc-settings/mass-flow. Answer no when asked to preserve profile

while flow leaves.

Note that outflow boundaries cannot be used in the following cases: If a problem includes pressure inlet

boundaries; use pressure outlet boundary conditions instead. If you are modeling compressible flow. If you

are modeling unsteady flows with varying density, even if the flow is incompressible. With the multiphase

models (Eulerian, mixture, and VOF (except when modeling open channel flow). You can find more

information about outflow boundary conditions in the FLUENT 12 documentation.

36

There are also enhancements for some of the other boundary condition types in FLUENT 12.

For pressure outlets, we have made the target mass flow rate option more robust and when you have more

than one pressure outlet present, you are able to set individual pressure limits. This is helpful for cases like

the manifold shown here.

Notes:

Profile Enhancements not included in this presentation

Linear interpolation of profiles: Enable the interpolation of values between points provided in a profile

(Beta feature in FLUENT 6.3)

Plot interpolated data on a face: Allow to plot the loaded profiles with respect to the coordinate

directions or time. Also allow to plot the interpolated profile data on a face thread. Plot with respect to

coordinate direction or time.

37

For pressure far-fields, we have added the ability to use cylindrical coordinates when specifying the flow for

both the density-based and pressure-based solvers.

Other development includes making non-reflecting boundary conditions compatible with non-conformal

interfaces and dynamic mesh in FLUENT 12.

38

Finally, in response to several long-standing customer requests, we have added two alternative mixing plane

profile averaging methods – mass-averaging and mixed-out averaging – to the area-averaging method

available in previous versions of FLUENT. These averaging methods are useful when performing simulations

using the mixing plane, like the axial compressor shown here.

39

Turbulence has been an area with active sharing between the FLUENT and CFX functional groups.

Turbulent transition modeling is available in FLUENT 12. Turbulent transition models are important for

detailed modeling of the transition from laminar to turbulent flow that occurs near boundaries. We have

implemented 2 models – the 4 equation SST transition model and the improved Walter’s model. The SST

transition model is recommended for general purpose applications and is intended to be used with the built-

in Langtry and Menter correlation, an ANSYS proprietary empirical correlation, that was developed to cover

standard bypass transition as well as flows in low free-stream turbulence environments. In addition, a very

powerful UDF option is included that allows you to enter your own user-defined empirical correlation, which

can then be used to control the transition onset momentum thickness Reynolds number equation. Both the

SST transition model and the improved Walter’s model were used to calculate the skin friction coefficient

and pressure coefficient on an airfoil in a verification case. The results from these simulations were then

compared to experimental data. As you can see in the plots, the results from both models compare

favorably with the experimental data, including the prediction to the experimental transition location at

x/c=0.12.

40

A number of LES and DES improvements are also in FLUENT 12.0. You are able to use the vortex and

spectral synthesizer methods of generating fluctuating velocity components at velocity inlets with LES

(available previously) and DES and pressure inlets with LES. Additionally, you are able to specify Reynolds

stresses profiles at velocity inlets for the vortex method.

In FLUENT 12, delayed DES improves the prediction of separation for external aerodynamics. With DES, an

unsteady RANS models is applied to the boundary layer, while the LES treatment is used in the separated

regions. Delayed DES pushes the region where LES is used farther away from the body, where the mesh is

more likely to be uniform, improving the solution and separation modeling. This will be an option for DES-SA

and DES-RKE.

Several new post-processing options are also available for LES and DES including the ability to display wall-

distance based Reynolds number and LES/DES Q-criterion post-processing.

There are also 2 beta features that I would like to mention in the turbulence area: The SAS Turbulence Model

and the ability to use of the K-Omega turbulence models (Standard and SST) for use with Eulerian

multiphase. These features will remain beta in R12. More infromation is available in the FLUENT 12.0 beta

feature documentation available at www.fluentusers.com.

Notes:

Other turbulence features not shown in the slides:

Dynamic SGS model for variable-density flows – external aero, jet flows, VOF with LES

GUI option for selecting the SA near-wall damping

Scalable wall function approach for wall function based turbulence models

41

In the area of acoustics, we have expanded both the Ffowcs-Williams Hawkings and broadband noise

sources acoustics models in FLUENT 12 to be compatible with the implicit and explicit density-based solvers.

We have also enhanced the export of acoustic data to LMS virtual lab so that we will be able to use CGNS

format for exporting both dipole and quadrapole data1.

Notes:

1Virtual Lab needs the exported data on the prescribed surfaces in the CGNS format in a single file per time

level exported.

42

Now I would like to talk about the multiphase enhancements that are new in FLUENT 12. In FLUENT 6.3, we

introduced the pressure-based coupled solver which is compatible with the VOF and mixture multiphase

models. For marine applications, PBCS with VOF significantly improves robustness. In FLUENT 12, a

multiphase coupled solver is available .This new pressure-velocity coupling option couples the velocity and

pressure equations for the Eulerian multiphase model. There is also an option to include and solve the

volume fraction equations coupled. The multiphase coupled solver is also compatible with the population

balance model as well.

Testing of the multiphase coupled solver shows improved steady-state convergence for many cases. For

some cases, the coupled multiphase solver clearly gives superb performance for steady state problems

compared to previous versions of FLUENT where most steady state problems had to be run in unsteady

mode. This is true for granular and non-granular cases. The example on this slide was solved using the

coupled multiphase solver in FLUENT 12. This simulation includes the population balance model and uses a

UDF to model boiling with a regime change. Convergence for this case was achieved using the steady-state

solver. In previous versions of FLUENT, the transient solver had to be used and convergence took several

times longer.

43

In addition to the coupled solver for multiphase, I would like to focus for a minute on one major model we will

be introducing in FLUENT 12.

This is the immiscible fluid model (formerly know as multi-fluid VOF model). The immiscible fluid model allows

you to model free surface flow, including surface tension, using two velocity and two temperature fields. The

advantage is that you have more degrees of freedom (two velocity fields and two temperature fields instead of

single field in VOF) to couple with difficult situations where classical VOF has problems such as surface

tension dominated flows, trapped gas bubbles near the wall, and large velocity and temperature gradients

across the interface. In addition, the ability to use the Geometric-Reconstruction scheme with the Eulerian

multiphase model allows you to more accurately resolve interfaces between the phases. The animations on

this slide show a bubble rising through a slurry of granular solids in water. The slurry is represented as a

granular fluid. For the sake of post-processing, DPM is used to track the red particles you see using the

granular phase velocity (done using a UDF).

44

Now I would like to talk about a few more additions to the multiphase models in FLUENT 12.

Starting with the VOF model . A numerical wave tank boundary condition is available in FLUENT 12. This

boundary condition allows you to specify a periodic, wave-like boundary condition at velocity inlets for free

surface modeling. The ability to initialize the flow field throughout the domain based on the wave profile

provided using a TUI option is also provided. This feature was used to model flow around a ship hull in the

image in the right.

Also for VOF, when you are post-processing your VOF solution you are now able to plot phase IDs when

more than 2 phases are present.

45

For the Eulerian multiphase model …

You are able to model filtration using the Eulerian multiphase model with the porous media models in FLUENT

12, including blocking the passage of some phases and temperature differences between the fluid and the

porous media.

Additionally, a universal drag law is available for simulations with arbitrary bubble sizes and distributions, like

the bubble column shown here. The universal drag law is available for the Eulerian and mixture multiphase

models.

An interfacial area concentration model is available in FLUENT 12.0 for gas-liquid flows as an alternative to our

full population balance models. The IAC model is available with the Eulerian and mixture multiphase models

and can estimate the interfacial area in a dispersed system and calculate multiphase inter-exchanges, including

mass, momentum and energy exchange based on this interfacial area. It does not calculate bubble-size

distributions. This model is computationally less intensive than the full population balance models and is

appropriate when the bubble size distribution is not explicitly required. Kernels are provided for bubble-liquid

flow regimes, but users can apply kernels for other flow regimes via UDFs.

Notes:

Outflow Degassing Boundary Condition for outflow boundaries with the Eulerian model: This can be achieved

using the pressure boundary condition or UDF based functionality. UDF isdocumented in the User's Manual.

46

Speaking of population balance, a number of enhancements have been made to the population balance

module in FLUENT 12.

We added an option to use the Ramakrishnan numerical method when using the discrete method for

population balance. The Ramakrishnan method provides improved accuracy but comes with a higher

computational cost than the default Hagesather method.

In FLUENT 12, you also have the ability to express breakage kernels using separate frequency and breakage

pdf functions.

New breakage pdf functions are also available as are new breakage frequency functions for gas-liquid, liquid-

liquid, and gas-solid flows and new aggregation kernels for liquid solid flows. These improvements improve

the modeling ability of the population balance module.

Notes:

Features not mentioned in the slides:

Improved drag coupling for QMOM and SMOM with the coupled Eulerian multiphase solver

Improved Conservation for QMOM: Ensure conservation of moments in the domain when using QMOM

New breakage frequency functions: Coulaloglou and Tavlarides for liquid-liquid is a beta feature

47

For both the Eulerian and Mixture multiphase models, we have added a new models for transferring mass between

the phases. While most of this work has focused on cavitation, I wanted to make sure you are also aware that

options are also available for modeling the transfer of mass between phases due to temperature changes that

cause evaporation and condensation to occur.

The cavitation model itself has been the focus of a lot of development in FLUENT 12. The FLUENT 12 cavitation

model is significantly more robust than previous versions. For most cases, you are able to run with default under-

relaxation factors and reach convergence in a stable manner. You are also able to model the viscous heating and

pressure work, needed to model the temperature rise caused by cavitation. This is especially important when the

temperature rise may be significant and exceed the acceptable limits of the surrounding materials.

In the example shown here, cavitation in a fuel injector is modeled using FLUENT 12. This fuel injector is filled with

fuel oil and fuel oil vapor. The images on the right side show contours of temperature and vapor volume fraction in

the fuel injector. As you can see from the residuals plot in the lower left, convergence for this case was smooth.

This simulation used the pressure-based coupled solver. The case was run using first-order discretization. Then,

the energy equation was turned on to model the temperature rise in the fluid. Once the first order solution reached

convergence, second order discretization was used to reach the final solution. In previous versions of FLUENT, this

simulation would have required babysitting and under-relaxation factors to be tweaked. In FLUENT 12, this

simulation was straight-forward with default under-relaxation factors used throughout the entire simulation. (page

down)

The CFX cavitation model (Zwart model) is also available in FLUENT 12 and you are now able to model cavitation

with LES.

48

The final multiphase area I will talk about is enhancements for the Discrete Phase Model…(page down)

We implemented a Dense Discrete Phase Model for FLUENT 121. (page down) This model allows you to use DPM

to model a secondary phase during your Eulerian multiphase simulations and permits the volume fraction and

momentum of the Lagrangian particles tracked with the DPM model to be accounted for in the continuous flow.

Thus, this model considers the voidage of the DPM model in the Eulerian phases. This model is efficient for

modeling size distributions in a single secondary phase in simulations like the hydrocyclone shown here. Post-

processing of the Dense Discrete Phase Model includes the ability to display averaged fields of the DPM model.

(page down)

49

We have also made some improvements to the standard Discrete Phase Model in FLUENT 12.

You are able to use massless particles when using the DPM model. A massless particle is a discrete element that

follows the flow and temperature of the continuous phase. It has no mass, no physical properties associated, and

no force is exerted on it. However, a User Defined Law can be assigned to be applied to the massless particle.

Tracking of massless particles is faster than that of other particle types. Massless particles are available with all

FLUENT models and are particularly useful for modeling residence time distributions in glass tanks, mixing vessels,

reactors, etc. using DPM. Massless particles were used to model residence time and melting index in the glass

tank shown here.

We continue to focus on improving the robustness and usability of the DPM model, including new development in

version 12 that improves the consistency of DPM results, include energy and mass balances with radiation and

combustion, allows you to include injections in read/write settings files, and development focused on improving the

robustness of DPM in cases with moving and deforming meshes and mesh interfaces and in parallel. Enhanced

reporting options include new DPM reporting options that allow you to export multiple DPM variables to a particle

history file, extensions for histogram weighting, and the ability to post-process particle solid species mass fraction

and particle surface reaction rates.

Notes:

1Specific DPM robustness and usability enhancements are: More consistent reporting of DPM results including

energy, mass balances with radiation and combustion. New DPM reporting options: Customized particle history file

that allows you to export multiple DPM variables to a particle history file; Injections included in read/write BCs,

Histogram Panel Extensions: ability to select appropriate weightings to the histogram and write it to a file, Consider

DPM mass/energy source terms in Flux Report; Ability to post-process the particle solid species mass fraction and

the particle surface reaction rates.

50

There has been quite a lot of activity in the reacting flows area for FLUENT 12 as well. In addition to the

Extended Coherent Flamelet Model and Exhaust Gas Recirculation models I mentioned earlier.

The DQMOM-IEM model for turbulence-chemistry interactions is available for gas-phase and liquid-phase

reactions and for stiff and non-stiff chemistry. This is an Eulerian transported PDF model that is significantly

less costly than the Lagrangian transported PDF model available in previous versions of FLUENT. You are

able to use this model to simulate liquid micromixing, which is occurring in the confined impinging jet reactor

(CIJR) shown here.

Notes:

Features not included in the slides:

New reports – heat of combustion;

Species mass fraction variables added to specific heat UDF macro: Temperature dependent sensible heat

and sensible enthalpy for fluid, solid, and mixture materials (no DPM)

Allow the user to optionally input mole fractions for species inputs instead of mass fractions.

Zimont turbulent flame speed wall damping: Provide the ability to model flame speed damping effects near

the wall.

Warning During Initialization for Eddy Dissipation: Warn the user that species mass fractions are initialized to

non-zero values, when they initialize unsteady flow with the eddy dissipation model is enabled.

Inlet Diffusion for Species Off by Default: Do not include the species diffusion at inflow boundaries by default.

51

In FLUENT 12, stiff chemistry is now also available with the Eulerian multiphase model. This feature allows

you to model chemistry that is too stiff for the non-stiff solver. This feature was used in the example on this

slide. Heterogeneous multiphase reactions were used to model 16 reactions, included 6 reaction steps that

required the stiff chemistry solver with Eulerian multiphase.

52

We have also improved the segregation model for solidification and melting, improving accuracy, robustness,

and usability. The solidification model is used here to model negative macro-segregation in a mixture of Lead

and 19% tin mixture as the mixture cools. Negative macro-segregation contours are shown at four different

times and the patterns compare very well with the numerical results.

Notes:

Example based on: P.J. Prescott, F.P. Incropera, Convective Transport Phenomena and Macrosegregation

During Solidification of a Binary Metal Alloy: I – Numerical Predictions”, J. of Ht. Trans., Vol. 116, pp. 735-741,

1994

Beta features associated with solidification and melting: Solutal Buoyancy Boussinesq Model: Provide an

option to model solutal buoyancy with the solid-melt mode, Thermal Buoyancy Boussinesq Model: Provide an

option to model thermal buoyancy with the solid-melt model

53

Part of our focus has been on making chemistry faster and more accurate. We have upgraded to ISAT 5,

making chemistry calculations more accurate1. We have also improved the speed of PDF Table Lookup,

enable faster plotting of species for the non-premixed model, improved the speed if iterations for the non-

premixed model, and added automatic clustering in the flamelet and PDF tables.

Notes:

1The new ISAT is substantially more accurate than the old ISAT. In addition, it is designed to perform well for

'long' runs, which is typical of reacting flows, instead of short unit tests where the table is being built. This

does come with a computation resource requirement penalty. Primarily because the old

ISAT variably interpolates new points within the table, while the new ISAT inserts new points which is

expensive (but more accurate).

Specific features:

Improved Speed of PDF Table Lookup: Enable faster table lookups for cases using a PDF table; Enable

faster plotting of species for the non-premixed model; Improve the speed if iterations for the non-premixed

model

Automatic Clustering in Tables: Provide automatic clustering of points in the flamelet and PDF tables.

More accurate PDF table look-up

54

For surface reactions, improvements for surface reaction modeling are available as well including surface

coverage dependent reactions where the reaction rate may be a function of the fraction of sites open/covered.

The image here shows a rotating CVD where Si deposition is occurring. The case was solved with full multi-

component species diffusion and detailed chemistry: including 17 species and 39 gas and surface reactions.

In FLUENT 12.0 a coal calculator is available in the Gui and TUI for entering coal parameters via proximate

and ultimate analysis.

And you are also able to import RIF flamelet files generated by the CFX RIF utility available with CFX.

Notes:

Related feature: Ability to post-process the particle solid species mass fraction and the particle surface

reaction rates.

55

In the area of pollutant modeling, a number of improvements are also available in FLUENT 12. The new

Moss-Brookes soot model is significantly more accurate than the one-step (Khan & Greeves) and two-step

(Tesner) soot models available previously. Enhancements for thermal NOx modeling include the ability to

solve for the temperature variance transport equations, available Beta and Gaussian PDF shapes, and

several option to define the temperature upper limit in the PDF integrations. Finally, in the pollutant area,

FLUENT 12.0 allows you to simultaneously model solid and liquid fuel NOx.

A few new options are also available for use when you are using KINetics to model your chemistry. You are

able to use KINetics to model multiple surface reactions. You are also able to use KINetics to evaluate

specific heat and enthalpy during your simulation. Previous versions used FLUENT to do these calculations

and you can o continue to use FLUENT 12.0 for these calculations.

Several new user-defined functions hooks are also available in FLUENT 12. You have access to the

properties for the partially premixed model and the turbulent Schmidt number. You are also able to specify a

temperature dependent sensible heat and enthalpy for fluid, solid, and mixture materials using a UDF.

Notes: List of new UDF hooks:

UDF Access to Partially Premixed Properties; UDF Access to the Turbulent Schmidt Number

User Defined Heat Capacity UDF: option to define temperature dependent functions for Specific Heat and

Sensible Enthalpy for fluid, solid and mixture materials (not DPM particles). This is already a beta feature in

Fluent6.3

Add species mass fractions to Cp UDF hook: Provide access to the species mass fractions in the UDF hook

for Cp.

56

Now I will spend the next few minutes talking about the Real Gas model in FLUENT 12.

Perhaps the biggest news is that the real gas model is now available for the pressure-based solver in

FLUENT 12. This implementation is in response to many customer requests.

As part of this focus of the real gas model, a new built-in Aungier-Redlich-Kwong law is available. The

Aungier-Redlich-Kwong model is selected in the Density drop down list, in exactly the same way as the ideal-

gas law. The required critical properties are available in the materials data-base. For mixtures, a mixing law

for the critical constants is used to define the critical properties of the mixture species. The new Aungier-

Redlich-Kwong law is in addition to the NIST-library and user-defined real-gas options that are available in

previous versions of FLUENT. All 3 of these options are available for the pressure-based and density-based

solvers in FLUENT 12.

In FLUENT 12, you are also able to model reactions with the real gas model using either solver when using

the Aungier-Redlich-Kwong law or user-defined real-gases.

To assist in post-processing your real gas cases, additional cell functions specifically for the real-gas model

provide relevant postprocessing capability. You are able to plot contours of Properties ..../ Compressibility

Factor, Reduced Temperature, Reduced Pressure, and the mixture critical constants.

The simple example on this case is the result from a simulation modeling subcritical CH4 combustion with

new built in Aungier-Redlich-Kwong model and the pressure-based solver. Contours of the compressibility

factor are shown.

57

Switching to heat transfer and radiation… In FLUENT 12, we have introduced an alternative view factor

calculation methods. Preliminary testing of the ray-tracing method, has shown it to be 30-40 x faster than

face-to-face calculations on a typical underhood case with the same accuracy.

There are several improvements for shell conduction that I would like to talk about now. Temperature

dependent thermal conductivity in shell zones allows you to model thin-walls where the thermal conductivity is

varying with temperature due to the properties of the material.

The shell conduction model is compatible with semi-transparent walls in FLUENT 12, allowing you to use the

shell conduction model with semi-transparent walls. This will be particularly useful when modeling thin semi-

transparent sheets like reflectors, thin bulbs, and thin lenses.

We have also done some development work that improves the performance of the shell conduction model in

parallel. The recent data shown in the chart displays the speed-up of the shell creation algorithms in FLUENT

12.0.9 (dev version, not beta version) compared to FLUENT 6.3. We expect additional speed-up in the

release version of FLUENT 12.

I would also like to mention on small addition to the Solar Load Model in FLUENT 12. You now have the

ability to specify whether or not the sun shines into the flow domain at boundaries, like velocity inlets. You will

also be able to set a solar transmissivity factor to determine how much sun shines into the domain.

Notes: Features not included:

Utility to Manage Surface Participation in the S2S Model: Provide a utility to more easily manage which

surfaces participate in the surface-to-surface radiation model.

Ability to Compute Faces Per Surface Cluster from the View Factors and Cluster Parameters Panel: Add a

Compute button to compute the faces per surface clusters for active surfaces to the View Factor and Cluster

Parameters panel

Improved Ability to Control Cluster Sizing: Provide greater control to the user to control the cluster size and

growth on the radiating surfaces.

58

There are also several enhancements for the discrete ordinates radiation model.

The treatment of partially specular walls has been improved. In FLUENT 12, you are able to model emission

and absorption even for entirely specular walls. Absorption at specular walls is based on the wall emissivity.

Also when using the DO radiation model, you are able to specify the beam direction as a profile. This can be

used to specify a beam direction normal to a curved surface, as shown in the example on this slide.

Finally, an additional option for the DO model allows you to specify the diffuse irradiation component at semi-

transparent walls. This option benefits simulations that use the DO model in conjunction with the solar load

model in particular.

Notes:

Features not mentioned in the slides:

P1 radiation enhancements: Account for the refractive index

UDF hook for black body emission factor (or Planck's function) for WSSGM: We have also added a UDF

hook to extend FLUENT’s Weighted Sum of Gray Gases Model by allowing access to the black body

emission factor (Planck’s Function). This access will facilitate the modeling of non-continuous bands using

the weighted sum of gray gases model. This ability will be particularly important for cases simulating

radiation in combustion applications.

1st-to-2nd-order blending with DO model: Provide a better than 1st order solution if 2nd order will not

converge.

59

I am very excited to tell you that a new model for heat exchangers is available in FLUENT 12. The dual cell

heat exchanger model uses separate co-located meshes for the cold and hot streams to simulate heat

exchangers. This model can be applied to parallel flow and counter flow heat exchangers. The dual cell

exchanger is able to account for flow and property variations in the flow fields. You are also able to model

non-rectangular heat exchangers when using this model.

Preliminary testing has shown the dual cell model to be slightly more accurate than macro model available in

previous versions of FLUENT (and still available in FLUENT 12). In the plot on this slide, top tank temperature

predictions for a heat exchanger simulation used to compare several codes are shown. Bar 1 is experimental

data and bars 2 and 3 are the macro model and dual cell models respectively. All of the other bars are

competitor codes. I am pleased to say that both FLUENT models outperformed most of the other codes. The

dual cell model results were also slightly better than the macro model results.

Notes:

Other heat exchanger features not included in the slides:

XY plot of NTU vs. Mass flow rate for heat exchanger model: The user shall be able to plot NTU values as a

function of mass flow rate.

Post-processing of the total heat rejection: The user shall be able to print or monitor the total heat rejection

rate if coolant inlet temperature option is used. Heat Exchanger Reporting though GUI: The user shall be able

to use GUI for heat-exchanger report. The quantities available in TUI will be made available through GUI.

60

The final area that I will cover today is development in the area of fuel cells.

The solid oxide fuel cell (SOFC) module is now available under the resolved membrane electrolyte assembly

framework in FLUENT 12. This is the framework that the proton exchange membrane (PEM) fuel cell module

uses. Bringing the SOFC module under this framework offers many advantages, including the ability to use

non-conformal interfaces in your SOFC fuel cell simulations as shown in the example.

Additionally, improvements for the resolved MEA framework are available in FLUENT 12 for both the SOFC

and PEM fuel cells. These improvements include automation of the stack set-up, used for the fuel cell stack

shown here and a number of new modeling options including the ability to restrict gas diffusion across the

membrane and model flow and species transport inside current collectors as well as the ability to simulate

multi-component diffusion and the temperature dependent leakage current. For PEM Fuel cells, you are also

able to model non-isotopic electrical and thermal conductivities in the gas diffusion layer. These

improvements allow you to model fuel cells easier and more accurately than ever before.

Notes:

Features not included in this slide:

TUI now available, Electrolysis

For the unresolved (zero-thickness electrolyte) SOFC model: Ability to model temperature dependent leakage

current; Time-dependent total current and cell voltage inputs, user-specified CO/H2 split

61

There are a number of other improvements available in FLUENT 12.0. Here I will speak about a few that

enhance usability of FLUENT 12.0.

When using autosave, you are able to either force FLUENT to save a case file with every data file or to allow

FLUENT to decide when to save a case file. This feature helps avoid not having the correct case file for auto-

saved data files and will be especially important for cases where the mesh is changing, such as sliding mesh

and moving/deforming mesh simulations. Also in FLUENT 12.0, a new Solution Files management panel

allows you to select and load previously saved states created by autosave.

When running a transient simulation, automatic export now lets you export multiple file formats or variables.

Read/write boundary conditions has been replaced by read/write settings file. The settings file contains all

case settings with the exception of the mesh. Current model settings will be discarded when a settings file is

read.

Newly available wildcards are available in the TUI for boundary and cell zone selection.

The robustness of the TUI journal mechanism has been improved. Only successfully completed commands

are recorded, full commands are recorded including default values and full command path, and entire

commands are now recorded in one line.

A number of new case check rules are l also be available in FLUENT 121.

Notes: 1New case check rules. Please see the user doc for details:

Case check for MRF initialization; Case check for VOF pressure discretization; Case check for partial

enclosure temperature; Case check for heat exchanger model requires porous zone definition; Case check for

DO/Energy coupling; Remove case check rule for PRESTO with buoyant flows; LSQ as recommended

gradient method for higher order; Case check for mesh quality parameters; Case check recommendation for

cavitation modeling; Case check recommendation for P1 model under-relaxation factor equal to 1.

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Some post-processing enhancements have been covered in previous slides. Now I will discuss for a few post-

processing enhancements that have not been mentioned previously. FLUENT 12 is able to calculate

moments about any axis provided by the user (not just X, Y, Z). This is useful for calculating moments when

the axis of interest is not aligned with a global axis.

The PNG file format is supported when saving pictures (hardcopies) in FLUENT 12.

Some improvements are also available for use when working with software provided with our partners. You

can import mesh files in the binary Tecplot format into FLUENT 12.0. When exporting files to EnSight, you

can now export internal surfaces to EnSight, export cell-based data1, and create export transient data to

EnSight from a set of existing FLUENT data files at various time levels.

Notes: Miscellaneous features not mentioned in the slides:

UDF Hook After Case and Data Read: Provide a UDF hook called after the case is read in and build_grid is

called, and one after the data file is read in. Notes:

Porous media: Robustness and accuracy enhancements to the dbns porous-media implementation

Extend the Non-Newtonian Power Law model to be consistent with the formulation used in Polyflow

Extend the Herschel-Bulkley model to be consistent with the formulation used in Polyflow

Piece-Wise Polynomials Default for Cp: Set the default specific heat values for gas phase materials taken

from the data base to be piece-wise polynomials

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As mentioned earlier, all of the new features coming in FLUENT 12 are not included in this presentation and

notes. For a detailed list of features, please view the FLUENT 12 Documentation and Release Notes.