Most of the time, when a character gets shot in the leg in a movie, they keep hobbling along as if nothing had happened. Action heroes seem to be able to brush off the gunshot wound, merely wincing as if they’d been stung by a bee. But the reality of getting shot in the leg is much more grisly.

Leg wounds—particularly from gunshots—can lead to limb amputation or even death, especially if some shrapnel or piece of the bullet manages to rupture a blood vessel. You don’t see much of that in action movies, unless the director was going for a gritty, realistic style, or a character’s death was emotionally significant in some way. When us real people get shot in the leg, it’s almost always an emergency.

But thanks to some nifty 3D modeling technology, scientists were able to model the fluid dynamics of a bullet wound to the leg. Other researchers have modeled blood’s fluid dynamics and the effects of gunshot and shrapnel wounds before, but this is the first time it’s been done for the legs. Gunshots aren’t the only pitfalls an aspiring action hero (or more realistically, a soldier) might face, as leg injuries can arise from mines and IEDs as well. 

The simulation was crafted from scanning different sections of the leg: the hard bone, soft tissue with muscle and blood vessels, and skin. Previously determined blood flow rates from arteries and veins and a well-known fluid dynamics model. This allowed simulation of how much blood left the body as a result of the bullet passing through different sections of the leg.

These simulations would ideally be used for combat medic training, giving them a virtual patient that responds in the way a real bleeding leg would. The researchers developing the simulation hope to one day run it in real time so trainee medics can apply the necessary treatment—like a tourniquet or drugs—and immediately view the realistic reaction.

Currently, aspiring medics use real animals to study injuries, which the researchers would like to change. Right now the equations necessary for real-time simulated fluid dynamics are too computationally demanding, unfortunately. The models also don’t yet address broken bones or multiple wounds on the same limb. But the researchers hope to add more variables as the models become developed further.