Students use fluid dynamics to study the fictional question.
While some science is life-changing, other times you read study results and wonder why money is going into confirming obvious things — like that cereal tastes better with milk than water, that overeating can lead to weight gain or that cats really do ignore you on purpose. In even odder cases, scientists look to understand how fictional scenarios might play out in real life.
XKCD author Randall Munroe’s series of What If? posts are a perfect example of this: He answers questions like “What would happen if one tried to funnel Niagara Falls through a straw?” or “What would happen if I dug straight down, at a speed of 1 foot per second? What would kill me first?”
Recently, students from the University of Leicester decided to use fluid dynamics to calculate how long it would take a vampire to drain an average human’s blood. They published their findings in the Journal of Physics Special Topics, a peer-reviewed student journal run by their department of Physics and Astronomy.
Their findings? It would take only 6.4 minutes to drain 15 percent of a person’s blood from their external carotid artery.
To calculate this, the students had to make a few assumptions.
First, they assumed that the five arteries that split from the aorta — the main artery in the body — are of equal thickness and modeled them as smooth tubes. Second, vampire fangs were assumed to leave a 3/16 inch (5 millimetre) wide puncture wound and third, it was determined that the vampires would drink, rather than suck, the blood, which made the pressure equivalent to air pressure. Finally, human blood in the fictional scenario was determined to be at room temperature, and gravity was neglected.
They calculated the time it would take to drain 15 percent of a human’s blood (1.58 pints or 0.75 liters), because that is the turning point after which heart rates change.
“As a result, our goal is to find the time it would take for a vampire to drink 15% of a human’s blood and to be able to make a swift get away and minimalize [sic] the effects on the circulatory system,” the students reported in their paper.
Recently, researchers from Duke University in Durham, North Carolina, created a new supercomputer simulation of blood moving around the entire human circulatory system. The software, based on a single person’s body scan, takes into account every artery that is at least 1/32 inch (1 millimetre) wide. Perhaps technology like that could one day be used to improve the accuracy of the students’ vampire results, eliminating the need for some of the assumptions.
Then again, aren’t there more important medical scenarios to be researching?