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macfly March 6, 2014 11:43

data sets comparison, subtraction: cumbersome

I'm playing with a trial version of Ensight and I find it very cumbersome to compare 2 different cases. Here is how I do it, please tell me if there is a simpler way:

1. Open 2 cases in 2 different viewports.

2. Create a 3rd viewport.

3. Copy all parts of Case 2 and and associate the copied parts to the 3rd viewport (see tutorial EnSight10 FLOW-3D Part 1 at about 7:20 to learn how to associate parts to viewports, plot different variables of the same Case in different viewports...)

4. Select original parts of Case 2 and Create a Calculator => Predefined Functions => create a CaseMap of a scalar or a variable from Case 1 onto original parts of Case 2. Let's say I named my CaseMap "Tcase1", corresponding to temperature from Case 1 mapped onto original parts of Case 2:
- Variable name: Tcase1
- Expression: CaseMap(1,TEMPERATURE,1)

5. Select original parts of Case 2 and Create a Calculator => Build your own functions => create a variable with an expression containing the CaseMap, for example the difference between temperature of Case 2 and temperature from Case 1:
- Variable name: deltaT
- Expression: TEMPERATURE-Tcase1

6. Plot the new variable on the 3rd viewport that contains all the copied parts from Case 2.

That's it, cumbersome isn't it?

kevincolburn March 7, 2014 12:13

data sets comparison, subtraction: cumbersome

That is certainly one way to compute the difference between variables, and be able to display the original (case1), the subsequent (case2), and the difference all at the same time in the session of EnSight.

However, viewports are separate from cases, so the multiple viewports are not necessarily needed, if all you are trying to do is subtract the values. So, more precisely, if all you are trying to do is subtract the values, then all you need are steps 4 & 5 (CaseMap, then subtract).

If you are attempting to view both the original, the second case, and the difference all at one time, then the steps that you outline are fair. All can be captured in a macro, so that it is only a single click to perform all of that, if you are looking to simplify that process for your use.

Let us know if you have any questions, or would like additional information, we are here to help.

-Kevin (

macfly March 7, 2014 15:41

Hi Kevin,

Thanks for the reply. You guys at CEI answer quickly to emails and forum questions, it's appreciated.

Yes, I thought about writing a macro, but for it to be versatile I guess I would have to find how to program some loop through all parts of a given model, and I don't want to go on that journey now.

P.S. in french Francoise is the feminine version of Francois, careful with that! ;)

kevincolburn March 7, 2014 15:49

C'est ma faute. (A long time ago I was taught Canadian French, growing up only a few hrs from montreal).

Yes, the macro method is bit more involved, and would be useful if you were doing it a lot. But, for the casual use, it can be too much. The quick way would be do it once, save the commands that were journalled, and then just replay them again (this is not completely generic, but could be used to save time).

Let us know if you need anything else.


macfly March 28, 2014 18:21

I never got to be able to compare two cases side-by-side, each with their own independent legend in their respective viewport.

It's convenient in other softwares to be able to see, for example, the Case 1 in its own viewport, with its own temperature range and its own legend. Then the same for Case 2 in an other viewport.

In Ensight, if 2 cases are loaded, the range of the variable 'temperature' comprises the min and max of all the cases and there is no (easy) way to see what's the range of Case 1 and the range of Case 2.

Is there a way to do that? It looks as if 2 cases have the same nomenclature for all the variables, Ensight lumps all the values under the same variable for all variables. (hope my explanations are clear)

kevincolburn March 28, 2014 20:33

When you load your second, or subsequent case, just specify in the "Create new viewport for this case". This will setup the new case in its own viewport without any other work.

If the variables are named the same, EnSight tries to make things simple, and provide one variable. As they are the same variable, this simplifies things by being able "select both cases", and "color by temperature", rather than having to ask to color case 1 by temperature, and then case 2 by temperature.

If the ranges of each case are different, and you want to have different legend ranges for each case, that is very easy to do. Simply copy the variable over to a new name : Temp_Case2 = Temperature. Now, color Case 2 by "Temp_Case2", and you then have a second legend, and adjust that range separately.

Please feel free to use the normal support mechanism (email support@ceisoftware) or your local EnSight support representative.


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