Tecplot で水位の差分表示

Tecplot で水面を表示できますので、その差分をソフト内で計算・表示できれば、座標書き出しの必要性が小さくなります。

ま、できるでしょうと思いチャレンジしてみたのですが、できませんでした。水面のみ抽出した2つのZoneを指定し、差分を取るだけなので容易にできそうなのですが、ダメ。いえ、差分を取る計算式を入力する箇所はあるのですが、Zoneを指定すると"incompatible zones "というエラーが出るのです。

ググってみると、フォーラムに以下のような質問がありました。

http://www.tecplottalk.com/viewtopic.php?t=339

I have got a problem with the data -> alter -> specify equations function! I have tried for ages to visualize with this tool an anspect of my flow field, but it doesnt work.
description of my problem:
1. I load two files into tec360 with the same geometry datas but other flow fields. This works, and so i can see 10 zones (5 of each loaded files)
2. What i wanna do now is to subtract the pressure level of the first file of the second one. (zones 1-5 are from the first one, 6-10 from the 2nd one)
3. So i go into the specifiy functions tool and write:
{pdelta} = {p0}[6] - {p0}[1],{p0}[7] - {p0}[2],... (and so on for all the corresponding zones from 1 to 10)
-> but now i cannot compute this value pdelta and visualize it...-> if i try to compute it, there are three error messages which appear:
1. if i don't select any zone in the 'zone to alter' list, the error appears: 'invalid zone set requested'
2. if i select all zones, the following error appears: 'incompatible zones referenced in equation'
3. and when i select only a part of the zones, e.g. for the equation{pdelta} = {p0}[6] - {p0}[1] the zone 1 & 6, the following error appears: 'must alter all zones when creating a new variable'
So my question is, how can i compute and visualize the problem i described? what is wrong with my equation? Is it the syntax or has it to do with my zone selection or status? 

驚きです。
私も、まったく同じことをしようとして、同じところで躓いていました。 欲しい機能もわからないところも同じということです。この質問には解決策が載っていませんでしたので、Tecplot にその機能はないということなのでしょう。マクロを組めば、できるかもしれませんが。

代わりと言っては何ですが、1ステップ毎の計算は可能でした。欲張らないことですね。

http://www.tecplottalk.com/viewtopic.php?t=1124

In order for Tecplot to perform a calculation involving more than one zone (like the time average) all the zones involved have to be "compatible". That is, they have to have the same underlying order, and the same number of data points.

The "incompatible zones referenced in equation" message means that at least one zone had a different oder, or different number or points, or both than the rest of the zones.

For these instructions, think of two incompatible zones, each with five variables (X,Y,Z,T,P), where T is Temperature and P Pressure. And suppose that you want to subract P of zone 1 from P of zone 2:

1) Go to Data/Alter/Specify Equations and create two new variables, by highlight both zones in the Zone to Alter box and entering two equations like these: 

{P1} = 0
{P2} = 0
Then click Compute.
Both of your zones will now have two extra variables. 

2) Still in Data/Alter/Specify Equations, highlight only the first zone in the Zones to Alter box and then erase the two equations you entered moments ago and enter this one:
{P1} = {P}
and click Compute. This will copy P of Zone 1 into P1 of zone 1.
Now you can close out of Data/Alter/Specify Equations.  

3) Go to Data/Interpolate and choose a method. Select Zone 1 as the Source zone and Zone 2 as the Destination zone and P1 as the variable and click Compute. This will interpolate P1 of Zone 1 onto P1 of Zone 2.
P of Zone 1 has now been transferred to 

4) Now close out of Data/Interpolate and go back to Data/Alter/Specify Equations. Erase an equations that are present, and select Zone 2 in the Zones to Alter box.
Then enter an equation like this:
{P2} = {P1} - {P}
and click Compute. P2 of Zone 2 will now hold the result of the calculation of P of zone 1 - P of zone 2

なるほどです。確かに、抽出した水位の座標はそれぞれ異なりますので（水面（Z）だけでなく、なぜかXYも微妙に違う箇所がある）、エラーを吐くわけです。
本来は、上側の質問のように複数のタイムステップ同士を比較したかったのですが、贅沢は言えません。後者で実施してみると、うまくいきました。

続く。