m0darn

I have taught myself the skill of making very good alcohol, which can be used medicinally, and for barter.

It occurs to me that coffee/caffeine will also be highly valuable for barter in any scenario involving disruption of supply chains. I should put some with my emergency kit.

This also led to the invention of map contour lines iirc

Thanks, I can’t read the notes but the graph is pretty good.

Edit: … Coefficient of drag seems same in laminar regime, the surface treatment seems to only improve efficiency or make no change

Furthermore, the DMR-applied surface consistently showed a drag coefficient lower than that of the smooth surface up to the highest measured Reynolds number (3.6 x 10⁶)

This is the most surprising finding to me. The treated surfaces even exhibited lower drag in the turbulent flow regime.

Wait, is it also lower in the laminar region? Or is it higher in the laminar region, but laminar region lasts longer so overall improvement? Man a graph would be nice…

From the article:

This principle is fundamentally different from the effect of dimples on golf balls. Dimples reduce pressure resistance by intentionally turbulizing the airflow and suppressing backward separation. DMR, on the other hand, delays the transition [to turbulent boundary layer flow], thereby suppressing not pressure resistance but the wall friction itself. They are opposite mechanisms.