Saturday, March 26, 2011

Baldness and the fluid dynamics of showering

Isn't one of the best feelings in the morning the luxury of having a nice stream of hot water flow over your head and down your back and shoulders? I say yes! And since you don't have the privs to post original messages to the blog, my vote counts for a lot :)

Over the last couple of months since I've had the PICC and CVC lines it's been hard to do that. I have some various wraps to keep the lines dry but I've been trying to avoid getting the right side of my chest and arm wet so I've missed that nice morning soak. Adding insult to injury, as I really started to get bald about 6 weeks ago  the top of my head started to get cold in the shower. The warm water would hit my shoulders, splash up over my head and I'd feel cold drops on my head. This was surprising to me - you'd think that a spray that's only in the air for a second and travels only about 10-12 inches wouldn't cool down much. But with the wonder of both conductive and convective heat transfer at work, the water cooled down enough to feel cool on my scalp.

But - and here is the big insight to this morning's geeky post - when I took my shower this morning my head felt warm! I found this very intriguing. I believe this is because I have grown a bit of peach fuzz on my head:

I'm postulating that the droplets are disturbed as they hit the peach fuzz on my head and induce laminar flow across my noggin. This smooth flow of water with even temperature reduces the overall effect of conductive and convective heat transfer that is induced when my skin gets wet. So just this small disturbance in the surface structure of my head is enough to change the surface temperature so that my nerves are telling me - "hey, this is nice and warm" as opposed to two weeks ago, when my neural net was saying: "wow, this sucks. We're getting cold drops of water on our head."

I think this is one of the great, cool things about science. Qualitative analysis and quantitative measurements together often lead to new insights. I would never have thought that there could be this much of a difference from just a tiny change in my scalp surface. But I have at least one data point that says that this is definitely so. I admit the statistical universe is very small and I will work to repeat the experiment over the next few days. And when this last blast of chemo courses through me I'll probably re-lose my peach fuzz so I can then recheck my previous experience of getting cold drops of water on my head.

So there you have it! Perhaps a pretty lame analysis but I thought it was pretty good to have these thoughts before 6:30 on a Saturday morning!!!

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