Amplitude modulation of nonlinear waves in a fluid-filled tapered elastic tube

In the present work, treating the arteries as a tapered, thin walled, long, and circularly conical prestressed elastic tube and using the reductive perturbation method, we have studied the amplitude modulation of nonlinear waves in such a fluid-filled elastic tube. By considering the blood as an incompressible non-viscous fluid, the evolution equation is obtained as the nonlinear Schrodinger equation with variable coefficients. It is shown that this type of equations admit a solitary wave type of solution with a variable wave speed. It is observed that the wave speed increases with distance for narrowing tubes while it decreases for expanding tubes.