If you pour liquid from a regular juice box, and there is no air flowing into the container, then the liquid will squirt when it exits the open lid. But if you make a hole on the opposite side of the lid, so there are two holes. The original hole for pouring the liquid, and the second hole to create a flow of air into the container, the stream of the liquid will then be more smoothly and reduce the squirting. My question is whether there is any equation to calculate how big the hole for the airflow must be, before the stream of the liquid leaving the juice box will be smoother, and not squirt. I've tried researching this for quite some time, but I've not find anything relevant.