Sinking a Japanese Penny in Oil

Let's take a look!

Watch the video on YouTube.

What kind of experiment is this?

Experimental procedure and explanation:

• This experiment is similar to “Sinking a Japanese Penny Underwater” but the behavior of the penny is different.
• By changing the liquid from water to oil, we change the viscosity (the tendency to resist a quick deformation), and the growth of separation vortices becomes more difficult. In oil, separation vortices will not grow too large, they are symmetric, and they are difficult to be formed from the object (penny). Therefore, there are no inconsistent forces acting on the object, and it falls in almost a straight line.
• Academically speaking, this illustrates that “the influence of viscosity is stronger because of a smaller Reynolds number.”

[Keywords]	viscosity, separation
[Related items]	Sinking a Japanese Penny Underwater
[Reference]	“The Wonders of Flow,” Japan Society of Mechanical Engineering, Koudansha Blue Backs, pp. 16-21 “Illustrated Fluid Dynamics Trivia,” by Ryozo Ishiwata, Natsume Publishing, pp. 28-29