Question

John has two identical water barrels in his backyard. One day during the self-isolation period, he gets bored and rigs up a short spout at the bottom of each barrel, which allows it to freely drain out into his yard. The barrels are identical in every way, except one barrel has a sharp edge where the inside of the spout interfaces with barrel. On the other barrel, John has filed down that same corner so that it has a soft fillet (i.e. rounded edge).
Which barrel will drain faster?

Answer 1

Answer:

The barrel with the sharp edge will drain faster.

Explanation:

The barrel with filed down entrance will gradually allow water to flow out due to the soft round corner.

However, the barrel with sharp edge will create turbulent eddies because of the sudden contraction phenomenon at the exit point. This turbulent eddies will occur in the inside portion of the sharp edge. First, let us understand what Eddies are.

An eddy, is fluid current whose flow direction differs from that of the general flow. Eddies can transfer much more energy and dissolved matter within the fluid and they actually mix together large masses of fluid. They generally become more numerous as the fluid flow velocity increases.

Based on the above definition, we can see that due to the sharp edge created, the flow direction differs from that of the general flow thereby creating eddies that are usually turbulent which causes more outflow of water than that with the soft edge.