# Fluid dynamics explain how quickly a vampire could drain your blood

##### March 19, 2016

Throughout human history there have been tales of vampires – bloodsucking creatures of folklore that prey on their victims by draining their life essence, usually via the blood.

To coincide with the 85th anniversary of Universal Pictures' 'Dracula' starring Bela Lugosi, should you (unfortunately) be assailed by a vampire, students from the University of Leicester's Department of Physics and Astronomy have used to examine how long it would take for the undead fiend to drain an average human's – and have calculated that it would take only 6.4 minutes to drain 15 per cent of the blood from the external carotid artery in a human's neck.

15 per cent was used as the benchmark as any more causes the heart rate to change, while less can be taken without affecting the circulatory system of a human.

The aorta, the of the body, splits into five other arteries. For the purpose of the study the team was concerned with the velocity of blood flowing into only the common carotid artery.

They also assumed the five arteries are of even thickness, enabling them to calculate the velocity of blood flowing into the common carotid artery.

By examining the average human blood pressure in arteries measured relative to the air pressure, this gave the students the pressure difference.

They then worked out average density of blood at room temperature and were able to deduce how much blood would come out of a puncture in a human's neck (with vampire fangs assumed to leave puncture holes with a width of 0.5mm each).

Considering the human body has an average of 5 litres of blood and that a vampire might feasibly take 15%, in the study a vampire would drain 0.75 litres of blood, and by their calculations it would take 6.4 minutes to do so.

The students presented their findings in a paper for the Journal of Physics Special Topics, a peer-reviewed student journal run by the University's Department of Physics and Astronomy. The student-run journal is designed to give students practical experience of writing, editing, publishing and reviewing scientific papers.

Course tutor, Dr Mervyn Roy, a lecturer in the University of Leicester's Department of Physics and Astronomy, said: "Every year we ask each student to write around 10 short papers for the Journal of Physics Special Topics. It lets the students show off their creative side and apply some of they know to the weird, the wonderful, or the everyday."

The paper 'The Draining of a Lifetime' is available here: physics.le.ac.uk/journals/index.php/pst/article/view/855/624

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##### Osiris1
2.3 / 5 (4) Mar 19, 2016
Why is this in a physics site. Only dullards believe in 'vampires' of the human kind. The same kind that read comic books and are never found as even sophomores at any engineering or science major offering institution.
##### compose
Mar 19, 2016
This comment has been removed by a moderator.
##### kochevnik
3 / 5 (2) Mar 19, 2016
Vampire cult, I suspect, originates from the belief that menstrual blood clots to produce children. This was common belief until 18th century. Taoists said a man could become immortal drinking it. In China it is considered the source of yin energy. From this blood was extracted 'oil of messeh' which was the oil used to create the Messiah (anointed one)

Blood is thicker than religion
##### someone11235813
not rated yet Mar 19, 2016
What's special about the 85 anniversary?
##### obama_socks
2 / 5 (4) Mar 19, 2016
Vampire cult, I suspect, originates from the belief that menstrual blood clots to produce children. This was common belief until 18th century. Taoists said a man could become immortal drinking it. In China it is considered the source of yin energy. From this blood was extracted 'oil of messeh' which was the oil used to create the Messiah (anointed one)

Blood is thicker than religion
- kochevnik

...and just as effective.
Hey, where's Stumpy/Otto. Stumpy/Otto should know a lot about sucking.
##### obama_socks
1 / 5 (2) Mar 19, 2016
What's special about the 85 anniversary?
- someone
If you have ever watched the movie "Dracula" with Bela Lugosi, you would understand. Personally, I liked the one with Frank Langella better as it wasn't as scary. There was another one with Gary Oldman and Winona Ryder. That was good too.
But the REAL Vlad the Impaler was one hellofa character. One mean SOB.
##### Osiris1
not rated yet Mar 21, 2016
So called 'vampires' if real would have an incredible appetite for human lives. Since their 'reproduction' is by biting and taking over a body with its internal 'curse' and not by sex and pregnancy which takes a lot longer, it is logical to assume that within a sickeningly short time the vampires would wipe out first the human species and soon afterward every mammalian species with 'blood'. The whole world could mathematically become vampire plagues as their numbers increase geometrically every day. Before that, however, starvation would set in as this 'pseudo-species that produces no energy would die en masse, ravenously hungry with nothing but each other's lifeless, bloodless, non-harvestible undead walking corpses to eat. AS they ALL run down on pseudo energy, the world would become a vast rotting charnel house of giga-death. This is the direct and unavoidable result of their oft written about life cycle.
Steven Hawking would maybe reason no differently.
##### geokstr
not rated yet Mar 22, 2016
I wonder how much taxpayer blood was sucked out of the body politic for this "study."