This fist-sized powerhouse beats (expands and contracts) 100,000 times per day, pumping 5 or 6 quarts of blood each minute, or about 2,000 gallons per day. So how does blood flow through the heart?

Blood clotting ... that we can model both flow conditions and the stiffness of the clot, which gives the most realistic picture of what’s happening. No other model can do that,” Zhao says. The system ...