Bladeless fans, airplane flight, hurricanes and diffusion…What do they have in common?

Dear SCI156 Student: Great post! I just watched a neat SciShow video today about blade-less fans (*which actually have blades it turns out) and how they exhibit Bernoulli’s Principle of physics. Pressure deficit is a key concept related to Bernoulli’s principle, but I always use the example of airplane flight and a piece of paper to explain Bernoulli’s principle. So bladeless fans are new great example- thanks @scishow

Bernoulli’s principle concludes that speed and pressure in moving fluids are inversely related. As fluid speed increases, the pressure decreases and vice versa. Fluids move from areas of high pressure to areas of low pressure. In other words, fluids move towards pressure deficits.

Your explanation shows me that hurricanes and the Coriolis Effect are explained in a very similar way and are also a great example of Bernoulli’s principle. I never thought about the connection before, thank you! Here’s your explanation:

“As a result, the high pressure air surrounding the center or “eye” of the hurricane is constantly rushing toward the low pressure void in the middle, but because of the Coriolis Force, the air that rushes towards the center is deflected. “

And thinking back to SCI 155 and physics, my explanation for how airplanes fly starts with a question:

If you took a strip of paper and held it to your bottom lip and blew air out of your lips, what do you think will happen to the paper when you blow on it?

Now try it:

Image result for bernoullis paper example

Photo credit: https://slideplayer.com/slide/9495455/29/images/5/Examples+of+Bernoulli%E2%80%99s+Principle.jpg

And here’s a diagram to describe what’s going on there:

Image result for bernoullis paper example

Photo credit: https://matthewrobin.files.wordpress.com/2013/09/paper-strip.gif

And here’s an explanation from a biologist (me). Can you see the similarities?

Fluid (liquid, gas) molecules and atoms move from an area of high concentration to low concentration. The vast majority of chemical passages across biological membranes occur through passive diffusion. This is not pressure regulation technically, but the central concept of atom deficit is similar here as in the physics examples.

Image result for passive diffusion

Photo credit: https://cdn.kastatic.org/ka-perseus-images/932a09a9bbf6ac995985e9240c613abc3ab5bff9.png

I am not sure that Bernoulli’s is an appropriate application here. In fluids, heat increases kinetic energy, which speeds diffusion. And as blood flows away from the heart, its velocity decreases which facilitates chemical exchange across membranes. When the blood makes its return to the heart, the velocity increases and less diffusion occurs. Help me figure this out. Is this a reasonable example of Bernoulli’s principle?

What do bladeless fans (physics), airplane flight (physics), hurricanes (earth science), and diffusion (biology) have in common? 

Thanks, Maggie

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s