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Top-down and bottom-up: Two approaches for... Hydrodynamics?

Yesterday we had one of our first full-evening rains of this Summer. It started raining around 15:00, and didn’t really stop until past 22:00. Most of the time, it was a low intensity rain. Also yesterday, Sergio and I started with the Debian course I recently talked about - Fun!
Now… This course is scheduled at Instituto de Astronomía, which is halfway between my work and my home. 19:00 to 21:00.
I decided to leave early, so we could check some pending details - At 18:00. I biked to Astronomía, about 1.5km. When I arrived, I was as wet as you usually get at a regular rain: I still had some dry spots under my arms and legs. Nothing terrible, although a bit coldish - Anyway, that’s a top-down approach for hydrodinamics, the approach most people are used to.
When we finished this session, I had to go out in a rush, as I had a meeting at 20:00 at Balderas (downtown Mexico City, ~25min away by metro). Of course, I was one hour late already, and adding the time it would take me to get home, leave the bike and run to the metro, I could not just sit and wait for the rain to get any easier on me. So I pedalled.
Contrary to what I originally expected, I didn’t get soaked wet in the usual pattern. Stronger rain leads to more rain flowing down the road. Yes, almost immediately I felt a cold shudder on my legs and back: The water sprayed from below by my wheels. Of course, the front wheel was even more fun, as it sprayed my face from below - My helmet has a small protuberance at the front to make some shadow, and tilting a bit my head forward prevented the rain from hitting my eyes - but the dirty water, with small bits of wood and whatnot, from the ground found an easy way to my face. My only defense was to close the eyes as much as I could without losing visibility. A strange excercise to do :) Anyway, that’s the bottom-up approach for hydrodinamics.
Anyway, by the time I got home, after an extra ~1.5km, my pants were basically a soup. My shirt was not exactly dry, but it still kept me a bit warm. I just ushered inside, grabbed a jacket, and went on for my second meeting.


Felipe 2007-05-26 15:39:43

Re: Top-down and bottom-up: Two approaches for… Hydrodynamics?

Ah, sí. Para los que hemos usado la bicicleta por un buen rato (y dejado de usar otro tanto) conocemos ese patrón causado por la lluvia, luego llegando a casa te tienes que limpiar la cola.

Si sigues con esto de la bicicleta es bueno comprar unos tabaparros, son fáciles de colocar y también hay baratos.