From Nosferatu to Ebony Dark’ness Dementia Raven Way, vampires have enthralled humans across time—although no vampire captured our imaginations more than Dracula (and possibly Edward Cullen). 2016 marks the 85th anniversary of Bela Lugosi’s take on the infamous bloodsucker, and to correspond with this milestone, students from the University of Leicester’s Department of Physics and Astronomy used fluid dynamics to determine roughly how long it would take for a vampire to snack on you.
Making vampiric assumptions
Of course, the time needed for a vampiric feast would be high variable, so the students began with several assumptions to simplify the calculations. First, they decided that their vampire in question wouldn’t be looking to drain all of the blood from the body because leaving a trail of corpses is a good way to be found out and staked.
And so, they decided that their vampire would consume about 15 percent of the blood in a person’s body—“to make a swift get away and minimize the effects on the circulatory system” wrote the authors in their paper in the peer-reviewed Journal of Physics Special Topics. 15 percent is about the cut-off point before the body stops being able to compensate and may go into shock.
Meanwhile, vampires typically feast on blood from the neck—or rather the common carotid artery the travels through it. This artery is one of five branches off of the aorta, or the main artery of the body that leads blood away from the heart. They knew the velocity of blood coming out of the aorta, so to calculate the velocity of blood flowing through the common carotid, they estimated these five branches were of even thickness. After this, they were able to figure out the new velocity of the blood in the carotid.
After determining the difference between human blood pressure in the arteries and air pressure, they were able to figure out the pressure difference. They, they determined the density of blood at room temperature, and after estimating that the vampire’s fangs would leave puncture marks of about 1/64th of an inch (0.5 mm) in width, they were able to deduce how much blood would come out of the wounds, and how fast.
Sanguine supper
The team’s calculations showed that it would take a vampire about 6.4 minutes to claim 15 percent of the five liters of blood found in the average human body–apparently about the same length of time it takes a man to decide if he wants to ask someone on a second date—which “this seems fairly reasonable considering it takes less than an hour to give 0.47 litres of blood when you donate from a vein,” wrote the authors.
Of course, the density of blood at human body temperature would mean it has a lower density and thus would flow faster than they calculated, and they also decided to use air pressure alone—as their vampire “will not be sucking the blood out of the human, rather just drinking it as it flows out of the external carotid artery in the human’s neck.”
This, they acknowledged, “would reduce the time taken and make the process more efficient.”
Unfortunately all of this means the vampire’s feast will be a more drawn out event than we thought. But hey, at least it comes with some cool powers after you recover from the shock.
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Image credit: Thinkstock
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