Flow inside a helical aortic arch



This animation, created by Leszek Zabielski, depicts time periodic laminar flow down a helical pipe. The diagram on the right shows the downpipe pressure gradient, and the instant in the cardiac cycle. The pipe is spiralling around an axis on the left. Counting from the left, the first diagram shows streamlines of the `secondary' flow in the pipe cross-section. The second diagram gives contours of the down-pipe flow component, while the third gives the down-pipe vorticity. Red contours are negative, so that a substantial reversed flow can be seen during the cycle. Note the rotation of the flow pattern due to the helical shape, the formation of boundary layers on the top and bottom of the pipe, which separate at the inner bend soon after the pressure gradient reverses following closure of the heart valve.

The pipe helicity and curvature are chosen to correspond to those in the mammalian aortic arch, while the flow parameters are appropriate for a dog of mass 20kg.

Dog :
   Mass                 --- 20 [kg]
   Aortic diamater      --- 1.68 [cm]
   Womersley number     --- 14.16
   Cardiac output       --- 37.3 [cm^3/s]
   Mean Reynolds number --- 706
   Peak Reynolds number --- 3560