Your understanding appears wrong.. otherwise the two 3cm anemometer readings are taken
outside the 5 cm pipe.
You need to check your understanding with Jed.
1cm away from the wall is too much for a small pipe
for a small pipe we used a mini pitot tube in the days to get closer.
Jed may approximated the 0.74 cm to 1 cm in communicating with you,
It may be that the traverse section is wider to make the measurements more accurate.
You have a claimed that this causes 50 % error in the flow measurements.
Can you show calculations/ profile etc that substantiate this claim?
RB - I'm going in the data in the paper, plus what I could get out of Jed here. I'm sure Jed can resolve the matter.
I have however not claimed 50% error - originally, befoe looking at the matter more fully, I said the error might be as much as 50%, and soon after that I tightened things up a bit. My best estimate of the error, having crunched the number inasfar as I can ATM, is 80% (20% error). And I have linked the calculations (and given the Re calculations, which other agree with) that indicate this. I did that in the post I made - not my first one, but when I was prompted to investigate much more fully and find numbers - a long time back. I gave my reasons and linked the source material from which I derived equations. I was hoping people like you would follow up on that.
You should also note the way this works. If something is not done in the paper to tie down an uncertainty - but COULD be inferred from the paper results with some additional assumptions and calculation, I will claim that the figure is uncertain. Not that it is wrong bit that it could be wrong, and give the bounds as understood. Further investigation might (usually does) tie this down further reducing uncertainty - especially because we have Jed here to clarify issues. I should point out that the paper should be doing this. In this case the paper mentions the problem, but gives anenometer results that do not show what the paper claims they show. Hence I tried to investigate further.
Not knowing right is different from knowing wrong. However, with these results that if real would transform physics most including me will treat not knowing right by default as equivalent to wrong, simply because transformations of physics don't happen that often.
I am always open to new information to make my assessment of this data change (in either direction - you will see that has happened - both ways - on this thread).