[joey-mastlab]

Hello all,

I need help plotting the drag coefficient on a transient flow past a flat plate. I have ran the simulation and I've tried to write expressions, but I can't seem to figure out how to plot the drag coefficient in the X direction.

Attachment 96247

Attachment 96248

[ghorrocks]

There are many ways of doing this, one which comes to mind is:
* Define a new variable (The "x" button on the toolbar)
* Define the variable to have your expression
* It is now a simulation variable available for post processing, like all the others.

[joey-mastlab]

Do I define the variable in the preprocessor or the post processor?

[ghorrocks]

You can do it in either. If you do it in the preprocessor you will need to solve again for it to be calculated. If you do it in the post processor it will be available straight away.

[joey-mastlab]

Oh okay I see, well I did that and the graph I get is a straight line instead of the curve im expecting. I may be looking at the problem the complete wrong way, the professor asked us to do it in Fluent but I have already been working in CFX and this seems valuable for me to learn how to do in CFX instead of just using another piece of software for one problem,

[ghorrocks]

So you need to work out whether the incorrect response is because you are not doing the post processing properly or because the simulation results are not accurate.

If you want us to help you there post some images of what you are getting. Also some images of your mesh and some images of the flow.