- Dr Val

# Let's Get Nerdy!

Updated: Jan 30

We're going to talk about noses today-but first, we're going to talk about laminar flow, Poiseuille's Law, and why size really **does** matter.

*ahem*

Everyone knows that drinking through a larger straw is easier than drinking through a smaller straw, even if you're drinking a thin liquid like soda or water. But if you stop and really check the difference between the two holes, it only takes a millimeter or two to make a huge difference in the amount of liquid you can move. What gives?

Let me introduce you to the __Hagen-Poiseuille Equation__, aka, Poiseuille's Law. The "*R*" is the important piece there-that's the radius of the tube that the flow is going through. Radius is essentially half of the widest part of a circle. You'll notice that's multiplied the the 4th power. This means that any change in that radius, even a teeny-tiny one, makes a HUGE impact on fluid flow. And since that "*R*" is on the bottom, and the equation solves for pressure changes (ie, how easy it is to move fluid), the bigger the better. Increasing the radius of a tube something is flowing through from 3 to 4 mm, for example, will change that part of the equation from 254 to 804.

The practical applications of this idea are everywhere, but for today, the focus is on airflow. A "typical" adult nostril is 10-12 mm wide, which means an *R* of 5-6 mm. Nasal valve collapse, deviated septum, and other issues can decrease that by up to 70% That's the difference between a straw and a coffee stirrer, and you can imagine the impact that has on the amount of air which can be moved!

**Still With Me? Great!**

Enter the concept of nasal dilators. Many of these devices can effectively reopen the nostrils and nasal passages, changing that *R* back into the 5 to 6 mm range-BUT. The devices themselves add at least 2-3 mm of material back into the nasal cavity, which offsets a large portion of their benefit.

This is why we kept SIlent so simple. Our low profile wire adds <0.5mm of material back into the nostril while opening that area with the same effect. This minimizes our impact on R while maximizing our impact on airflow-helping people #breatheeasily

#science #airflow #physics #laminarflow #nasaldilator #allergyfriendly