how to create blood flowing animation in unity3d

I am now making a virtual reality project about medical education,which includes displaying the blood flowing of whole body, i have the model with whole body circulatory system.
Now i want to simulate the blood flowing ,which blood goes out from heart, flowing through artery,then going back to heart through vein.
I want the animation with color changing through blood flowing direction.The only way i can think of is by setting the model’s vertex color ,but this way is too low efficient.
Is there any alternative way?
Thanks!

Yeah, setting the vertex color would be a huge pain. I think if you UVs are set up properly for it, you could get this effect with just a simple gradient texture on a material with a UV offset value tied to Time.time or a similar counter. The texture would constantly flow in the direction the material is offsetting, so it would look like blood moving through the vein. Does that make any sense?

Please Check my shader, this might help you.