Secondarily, should the fan be outside or inside the window?
Asking for a friend. (Me, help. I can’t remember physics, it’s too goddamn hot)
Edit: I’ve opened all the windows and set up a fan a short distance from the window pointing out and it’s reduced the temperature to near-tolerable levels. Unfortunately, venting through the attic was a no-go but moving things aside might make it an option next time. Thank you all, I appreciate the help!
Why so far from the window?
I think you get the benefit of the airflow pulling in air along its edge to push out with it.
Like pushing a bunch of water with a broom removes not only the water in front of the broom but also more water due to surface tension and inertia
It’s called the linguini effect.
Ohhhhhh the bernoulli effect?
Good ole vermicelli effect
In this case it’s called the brunelli effect
Its called the Chimichurri effect
It’s called the kimchi effect
It’s called the butterfly effect.
Oh yeah the bruscietta effect
It creates an effect where surrounding air is pulled with the stream due to the Bernoulli effect. It’s the same thing that pulls shower curtains in when you shower. If the fan is a bit inside the window, surrounding indoor air gets pulled into the stream, moving more air out in total.
Most of the replies are correct overall. But Mattias Wandel had identified another important factor. Fans don’t just “stuck from the back” and blow out the front. They sort of suck from everywhere including the edges. This means that if you’re putting a fan right up against the window blowing in you’re sucking some room air as well. If you’re putting the fan right up against the window blowing out, some of the air you’re blowing out comes from outside in the first place.
The ideal is then to blow out from 2-5ft away. This way all the air that’s blown is room air, and it’s all blown out. The venturi effect plays a small part. The Bernoulli effect? Equations? Explains why the air stays in a “tube” for a few feet away from the fan. Technically also explains the venturi effect… Everything is Bernoulli…
https://www.youtube.com/watch?v=1L2ef1CP-yw
This was a wonderful comment to read and video to watch, thank you
A fan creates kinda long “channel” in front of it and behind it, where the air is moving rather fast (at the speed that the fan creates). Imagine the narrow beam of light from a flashlight. You want that channel to go right through the window to have a good amount of air flowing.
I don’t know that you need to keep a distance from the window. I think 1-2m is just more practical than having the fan right inside the window frame.
Same reason why blowing on your hand close to your mouth is warm, but farther away is cool.