1.3.1 Starting ANSYS FLUENT on Linux from Windows

You can run parallel simulations on Linux clusters via the Windows interface. To access remote 64-bit Linux clusters for your parallel calculation, select the Parallel (Local Machine) option under Processing Options, then enable Use Remote Linux Nodes, which now appears under Options. The Remote tab in FLUENT Launcher will become available, where you can specify the remote ANSYS FLUENT Linux installation root path in the Remote FLUENT Root Path field. The Remote Working Directory field allows you to specify a working directory for the remote Linux nodes, other than the default temp directory.

Select one of the following Remote Spawn Commands to connect to the remote node:

• RSH (the default) is used to spawn nodes from the local Windows machine to the Linux head node as well as from the Linux head node to the compute nodes. If you want the Linux cluster to use SSH, then you need to set the FLUENT_NO_REMOTE_RSH to 1. You will also need to set up passwordless access.

• SSH is used to spawn nodes from the local Windows machine to the Linux head node as well as from the Linux head node to the compute nodes. To use SSH with ANSYS FLUENT, you need to set up passwordless SSH access. If you want the Linux cluster to use RSH, then you need to set the FLUENT_NO_REMOTE_SSH to 1. For more information about setting up SSH without a password, see http://www.debian-administration.org/articles/152
• Other allows you to provide other compatible remote shell commands.

Enable the Use Remote Cluster Head Node field and specify the remote node to which ANSYS FLUENT will connect for spawning (e.g., via rsh or ssh). If this is not provided, then ANSYS FLUENT will try to use the first machine in the machine file. If SGE is chosen as the job scheduler, then the SGE qmaster will serve the same purpose.

In addition to using the settings in the Remote tab in FLUENT Launcher, the following command line options are also available when starting ANSYS FLUENT from the command line:

-nodepath=<path>   is the path on the remote machine where ANSYS FLUENT is installed.

-node0=<machine name>   is the machine from which to launch other nodes.

-nodehomedir=<directory>   is the directory that becomes the current working directory for all the nodes. Additionally, this will be used as a scratch area for temporary files that are created on the nodes.

-rsh=<remote shell command>   is the command that will be used to launch executables remotely. This option defaults to rsh.exe but can point to any equivalent program. The form of this command should be that it should not wait for additional inputs such as passwords. For example, if you install SSH, and try to launch in mixed mode using ssh, the launch may fail unless you have set up a login for SSH without a password. For more information about setting up SSH without a password, see http://www.debian-administration.org/articles/152

As there are known issues with launching ANSYS FLUENT in mixed Windows/Linux mode from cygwin, it is recommended that you use the command prompt ( cmd.exe).

While ANSYS FLUENT case and data files are read from and written to the Windows machine while running mixed Windows/Linux simulations, parallel data files ( .pdat files) are written by the nodes and will not be available on the Windows machine. Therefore, the path specified for writing .pdat files should be a Linux path (you can set node's home directory if you want to provide relative paths). If you use the graphical user interface to read and/or write .pdat files, the directory component of the path is ignored and only the file name is used to read and/or write the .pdat file relative to the node's current working directory.

When working with mixed Linux and Windows runs that employ user-defined functions (UDFs), you should keep in mind that the file that you have opened for reading/writing on the host machine will not be available on remote nodes and vice-versa. You may therefore have to transfer data present on the nodes to the host and write it from host, (or distribute the data from the host to the nodes after reading the data from the host).

Setting Job Scheduler Options When Running on Remote Linux Machines

By selecting the Use Remote Linux Nodes option and the Use Job Scheduler option in FLUENT Launcher, you can set job scheduler options for the remote Linux machines you are accessing for your CFD analysis.

When these options are enabled in FLUENT Launcher, you can use the Scheduler tab to set parameters for either LSF, SGE, or PBS Pro job schedulers. You can learn more about each of the schedulers by referring to the Load Management Documentation. The following list describes the various controls that are available in the Scheduler tab:

Use LSF   allows you to use the LSF job scheduler.

LSF queue   allows you to specify a job queue and enter the queue name in the text box.

Use Checkpointing   allows you to use checkpointing with LSF. By default, the checkpointing directory will be the current working directory; however, you have the option of enabling Checkpointing Directory.

Checkpointing Directory   allows you to specify a checkpointing directory which is different from the current working directory.

Automatic Checkpoint with Setting of Period   allows you to specify that the checkpointing is done automatically at a set time interval. Enter the period (in minutes) in the text box, otherwise checkpointing will not occur unless you call the bchkpnt command.

Use SGE   allows you to use the SGE job scheduler.

SGE qmaster   is the machine in the SGE job submission host list. SGE will allow the SGE qmaster node to summon jobs. By default, localhost is specified for SGE qmaster. Note that the button allows you to check the job status.

SGE queue   is the queue where you want to submit your ANSYS FLUENT jobs. Note that you can use the button to contact the SGE qmaster for a list of queues. Leave this field blank if you want to use the default queue.

SGE pe   is the parallel environment where you want to submit your ANSYS FLUENT jobs. The parallel environment must be defined by an administrator. For more information about creating a parallel environment, please refer to the SGE documentation. Leave this field blank if you want to use the default parallel environment.

Use PBS Pro   allows you to use the PBS Pro job scheduler.