Richard Gilmore's Research: Using VNC Connection for Fluent v18.2 GUI access

Software Requirements and .bashrc setup:

Install putty, TurboVNC (www.turbovnc.org) or your favorite VNC viewer. Also, edit the .bashrc file in your user home directory and change FLUENT module version, and add module /Apps/TurboVNC/2.1.2 as shown below:

    module load ansys/fluent/18.2
    module load Apps/TurboVNC/2.1.2

Start an Interactive Session and start a VNCserver:

Start putty and login to Mio. Then start a interactive session with the following line:
$ srun -N1 --exclusive --pty bash -i

Start interactive session

Note the highlighted compute node name. In this case "compute031"

Note Compute node name

Start the VNC server on the compute node.
$ vncserver

command to start vncserver

The first time you start the vncserver you will be prompted to create a password for when you connect with the VNCviewer. Enter a password and re-enter to verify.

First setup of vncserver

The started vncserver should return the following. If you forget your password you can delete the passwd file in your .vnc/ home directory.

Starting the vncserver

Setup up a tunnel to this compute node by right clicking on the top bar of "putty" and select "Change Settings."

Open putty settings

Go to "Connection" in the tree menu under Category, and select "SSH" and then "Tunnels." Enter the "Source Port" 5901 Enter the "Destination" compute031:5901 (the "01" refers to the number following the colon after the node name in this case "compute031:1"). Putty tunnel connection settings

Every time you start a new GUI job you will need to setup a tunnel. The added tunnel should appear as the following in putty:

Completed added tunnel



Start VNC software on your computer and connect

On your Windows Desktop click start menu and type "TurboVNC" and start the VNCviewer program.

Starting your VNCviewer

Type the server address under "VNC server" localhost:1 (or whatever number that you put under Source Port).

Localhost connection

Enter your password from when you setup the vncserver. (or delete the file ./vnc/passwd in your Mio home directory and restart the vncserver).

Starting VNCviewer

The first time you open the connection your will receive the following prompt. Select the default setting.

Select default settings

This will connect you to the compute node on mio through your localhost and encrypted connection. The generic linux destop windows manager will open. Select from the "Applications Menu" the Terminal Emulator. Or use the grayed out button at the bottom.

Menu select way to open a terminal Alternative way to open a terminal

At the commmand prompt in the Terminal window start fluent with either the number of cores on your compute node or in serial mode.

Starting Fluent with one core


Starting Fluent with multiple cores



Start Fluent with a multi-node interactive session

At your Mio prompt request a multinode job with srun

Requied a SLURM job

Enter the folowing command to generate the nodes file from the SLURM job variable created when you get the job.
$ /opt/utility/expands $SLURM_NODELIST > nodes
This will output the list to the file "nodes" which you can look at with the command:
$ cat nodes

View of all nodes in job

Next we need the total number of cores available. Use the following to count the lines in the nodes file:
$ cat nodes | wc -l
this will output a single line with a number as show below.

Count the cores available

Next start fluent with the nodes file as an input for networking and the number of cores.
$ fluent 3ddp -cnf=nodes -t24
Where we are using 24 cores across two 12-core nodes.

Start fluent across multinodes

Fluent will open a GUI with full interactive capabilities across your VNC viewer connection

Fluent running interactive in V18.2



MAC OS only

You will need to open a second terminal to start the tunnel from once the SLURM job has connected to a compute node.
$ ssh -L 5901:compute031:5901 mio001
Then processed with opening your VNCviewer program and connect to localhost:1

Mac only tunnel setup

You can also use the native Mac VNC Viewer found in "/System/Library/CoreServices/Applications/Screen Sharing.app". Create a short cut and move it to your Application folder.