Spanwise/streamwise averaging in FLUENT/CFD Post?
 

Hi all,

I've done my simulations and am looking to plot the results. One of the things I would like to plot is my variable in a streamwise or spanwise location along the plane. I haven't been able to find a suitable solution so far.

The idea is to basically create a line, but instead of averaging (e.g. temperature) along that line, I would average all the values across it then plot the result on a graph.

Below is an example, except that I don't want to make so many lines. Would appreciate any ideas on how to proceed, thank you!

http://i61.tinypic.com/2vk19wi.png

In case anyone else encounters a similar problem, here's what I've done so far.

I've resolved the issue by basically scripting the generation of a large number of lines, about 400 in my case for a 1.5m length surface.

I used the Record Session tool in CFD post to generate 1 line, then opened the session file. I took that into Excel and expanded it to 400 separate lines (used Excel to automatically change the location of each line).

I then took all that and put it back into Command Editor in CFD Post to generate all my lines. I then had to generate a lengthave variable linked to the expression I needed in my case (heat flux) for each line by using the same method as above, got 400 average values and then simply exported them all out to plot.

I feel like there should be a simple command to be able to average ACROSS a line rather than along it but this is the only solution I have so far. If anyone else has an idea, I would love to learn so do chip in! Cheers :)

I don't think there is an easier way to do it. Maybe it would be useful to implement as a utility but anyone that attempts this problem would end up generating many lines/planes similar to how you did it.

The problem is that you cannot define, in general, an average across a curve because the the path "across the curve" is not defined. Sure we implicitly understand that we are trying to plot streamwise and spanwise averages along a particular coordinate but a general purpose software should only need to handle a general case and not worry about particular geometry. It gets more complicated for example with flow in pipes or annulus where you want to take azimuthal averages. A typical flow scenario is very different for different users. It is best to have the curve explicitly specified by the user at the expense of some convenience.

Sure, but I figured it's something many people are likely to need and there may be a particular utility for it.

Especially with non-flat surfaces, it'd be difficult to do what I did in my case. I could see it being used in pipes for example to look at changes in a given number of planes along a line through the pipe.

CFD Post lines already require the user to define the number of samples so I thought there may be a way to link those samples to a plane/line-averaged value but...!

Thanks for your input :)

I recommend you to try the same problem in CFX.Because in CFX,you can define expressions which make easier to compute the average value of some parameter in a particular domain
For example if you want to calculate average velocity at the outlet,you can define it as "areaave(velocity)@REGION:OUTLET"