How do I run Fluent interactively?

Please note: The FAQ pages at the HPCVL website are continuously being revised. Some pages might pertain to an older configuration of the system. Please let us know if you encounter problems or inaccuracies, and we will correct the entries.

The following instructions assume that you are a member of the Unix group fluent. The instructions in this section are only useful if you want to use the graphical user interface of Fluent, for instance to setup a job, or pre- and post-process a production job. If you want to run a production job, please refer to to instructions on how to start a Fluent batch job (see next section).

The Fluent program is started by setting a system variables FLUENT_ARCH and FLUENT_LICENSE_FILE to let the system know about the computing platform employed (lnamd64), the directory where the software resides and the license file used, respectively. It is also useful to include the directory with the Fluent executable in your path. Here is the command sequences to do all this (assuming bash and Ansys/Fluent version 14 on x86/Linux):

export PATH="/opt/fluent/ansys-14.0/v140/fluent/bin:"$PATH
export LM_LICENSE_FILE="/opt/fluent/Fluent.Inc/license/license.dat"
export FLUENT_ARCH="lnamd64"
export FLUENT_LICENSE_FILE="/opt/fluent/Fluent.Inc/license/license.dat"

These settings apply for the 64-bit version of Ansys14 Fluent on Linux, which is the default. 

There is a simple alternative for setting up your environment for the usage of Fluent: you can leave the above commands to usepackage and simply type

use ansys14

on the Linux workup node sw0010. This will automatically issue the above commands. You can also include the use command in your setup file (e.g. .bash_profile) if you are using fluent regularly on the Linux platform.

Then you invoke a graphical user interface by typing


For this to work you need to be on sw0010 (i.e. the Linux workup node) or another Linux node with interactive access.

The first choice you have to make is if you are solving a two- or a three-dimensional problem, and if you want to do so in single or double precision. You can do so by typing 2d, 3d, 2ddp, or 3ddp, following the fluent command. All commands can be issued in manually or by clicking on the toolbar on the top of the GUI and selecting the appropriate sub-choices. Note that if you want to type a command yourself, and you do not know what your choices are, simply pressing the Enter key will give you a list of applicable commands.

It is of course impossible to even outline how to use Fluent. In many cases, you will want to read in a case file, which has all the required information to describe the system you want to simulate. Such case files have the file extension .cas. Load them by issuing the /file/read-case command or selecting the corresponding menu-commands in the GUI. You can now check and display the grid, specify boundary conditions and material properties, initialize the flow, and perform calculations.

Results are usually saved by the /file/write-case-data command. During an interactive session, it is sometimes a good idea to keep a journal file which records all commands that you have typed in or issued via the GUI. This journal file can later be used as a template for a batch command file. Define the journal file with the /file/start-journal command.

Documentation for Ansys-14 Fluent can be accessed directly from the Fluent GUI by pressing the "Help" button on the upper right (html format), or in pdf format in


on the Linux login node sw0010.

Note that the documentation is only accessible if you are signed up as a Fluent user on our system.