As a much younger man I earned a living of sorts as a flight instructor for airplanes and gliders. I have piloted many glider types several high performance types. When I taught this subject it was not from an engineer point of view but like below so it is not a real tech type explanation but it is reasonably accurate I suppose.
When the air passes across a surface, like a wing on a glider, it initially attaches to the surface and more or less sticks to it until Mother Nature acts on it and it detaches from the surface. The time during which the airflow remains attached to the surface of a wing at least is called “laminar flow” and is often expressed as a percentage of the distance over the wing that it remains attached as laminar flow.
On most airplanes I flew like Cessna and Champ and older types they had virtually zero laminar flow. Some of those aircraft have fabric covered wings so the first stitch the air encountered then no more laminar flow because it gets tripped upwards. Laminar flow needs to be designed into the wing in a highly specific fashion. On the high performance gliders it is what they design. Especially with composite materials that can be made very smooth the wings can be designed then for the airflow to remain attached MUCH longer to the wing of a high performance glider. I believe the really spendy ones can achieve 100% laminar flow along portions of the craft during certain flight speed realms and by spendy I mean six figures and one seat and no engine… but those kind win world championships too
So laminar flow can dramatically impact drag but I am talking about wing flow dynamics in a very low speed flight realm. In fact laminar flow gets exponentially more difficult to maintain the faster you go. The worse case scenario is that once a surface is designed for laminar flow can no longer maintain that flow as laminar and attached then the drag becomes far worse than if designed for non laminar flow in the first place. In other words: the glider begins to drop pretty fast when this happens. Ain’t rainstorms a bitch lolz when you need that performance but the rain makes laminar flow just disappear?
This would apply I believe also to surfaces inside a pipe or column but it is beyond me how you could achieve laminar flow very far into a constricted space like a pipe. Laminar flow put simply is smooth flow of air over a surface. If the air runs into a rivet like on a wing it forces it upward and then not laminar. Same in a pipe methinks when it hits the first joint it detaches and no longer laminar. How could droplets of condensing vapor in a pipe not trip up the flow? In a glider you know because the altimeter starts to wind down rapidly from drag, a thingy called a variometer begins sounding very low tones, and if there is no place good to land then you poop. How would you even know inside a pipe??? No poop.
It’s why I vape out of a bag… no pipe. I better vape another bag and check it for drag… Then I hit the swimming pool.
I do believe laminar flow in this case is somehow related to marketing poop. But how would I know?