# Operate mirror and original
**URL:** https://discourse.paraview.org/t/operate-mirror-and-original/5319
**Category:** ParaView Support
**Created:** [September 11, 2020, 9:45am UTC](https://discourse.paraview.org/t/operate-mirror-and-original/5319 "2020-09-11T09:45:43Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@JDP](https://discourse.paraview.org/u/JDP)
#### Post date: [September 11, 2020, 9:45am UTC](https://discourse.paraview.org/t/operate-mirror-and-original/5319/1 "2020-09-11T09:45:43Z")
Hello, I have a flow field around an aircraft (from SU2) that has a sideslip angle (AoS) of let’s say 5 deg. I want to get the mirror flow field at -5deg. For that, I go to Filters-\>Transform and scale Y with -1 and X and Z with 1. After that, I create a Calculator and multiply by -1 the Y velocity or the values that have a component in Y. So far so good. Since the mesh is not symmetric (because it has some mesh deformations due to the AoS), I can see in the console that the mirrored model is cutting the original one if I show both at the same time, but that is fine.
However, now I want to do some operations that involve using the original flow field and the mirrored flow field, let’s say AoS\_original-AoS\_mirror, and I should see 10 deg far from the aircraft and some differences due to asymmetries near the aircraft. For that I select the two flow fields and apply the Filter-\>Append Attributes. I thought that Paraview would interpolate the results from one flow field to another and do the operations. To my surprise, Paraview scaled back the mirrored flow field instead of keeping it as it is. When I do AoS\_original-AoS\_mirror now, it gives me double the value in every cell, because the transformation (mirror) didn’t take place but the Calculator (multiply by -1) did. Does someone know how to keep that transformation in the Append Attribute?
Thank you,
Jose Daniel
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### Author:  [@JDP](https://discourse.paraview.org/u/JDP)
#### Post date: [September 14, 2020, 5:28am UTC](https://discourse.paraview.org/t/operate-mirror-and-original/5319/2 "2020-09-14T05:28:49Z")
It shouldn’t be very difficult, does anyone know why Paraview is mirroring it back when I do the Append Attributes command or how to fix it?
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### Author:  [@mwestphal](https://discourse.paraview.org/u/mwestphal)
#### Post date: [September 14, 2020, 7:23am UTC](https://discourse.paraview.org/t/operate-mirror-and-original/5319/3 "2020-09-14T07:23:12Z")
Your question is a litle bit unclear. Could you illustrate it with screenshots ?
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### Author:  [@cory.quammen](https://discourse.paraview.org/u/cory.quammen)
#### Post date: [September 15, 2020, 2:58pm UTC](https://discourse.paraview.org/t/operate-mirror-and-original/5319/4 "2020-09-15T14:58:55Z")
**Append Attributes** appends only arrays, it doesn’t append geometry or topology. Try **Append Datasets** instead.