Ah, once again, I get pulled up for being a bit brief in a story. Consider my wrist to have been slapped.
For those who might be wondering a bit at MechEngr's comments, it may be worth having a play with the following links
Reynolds number and dynamic similarity of fluid flows – Flow Illustrator
Similitude - Wikipedia
If it all gets a bit too confusing, don't worry about it. Just accept that the boffins can play with toys to get useful measurements in ways which don't always make immediate sense to the casual observer.
I recall a tale as an undergrad student - a bevy of politicians was being given a Cook's Tour of a water model of a local beach structure in the Mech Eng lab which had been set up to investigate flow patterns to figure out a way to reduce some erosion problems. One of the pollies was aghast - the model was nothing like the dimensions and depths of the real deal so, quite clearly, the whole thing was a bit of nonsense. Likewise, I can recall a Senate Enquiry with which I had some involvement. A couple of the worthy Senators just couldn't get their heads around what we were talking about in respect of some flutter stuff with a particular aeroplane's empennage - Dave will recall that one, I'm sure.
Sometimes, it gets a tad difficult to get folks to understand the protocols used when playing with similitude and flow modelling.