LDA measurements in a non-stenosed and a stenosed model of the carotid artery bifurcation

In order to gain quantitative information of the velocity fields in non-stenosed and stenosed models of the carotid artery bifurcation. Laser Doppler Anemometer (LDA) experiments have been performed. For this purpose a two component backscatter LDA system has been used. The experiments have been conducted in a 1:2.5 enlarged plexiglass model of the carotid artery bifurcation. Both axial and secondary velocities were measured as a function of time at locations of interest. The data were ensemble averaged and analyzed in the frequency domain in order to find characteristic flow phenomena. For the frequency analyses, the transfer functions between velocities at specific sites in the bifurcation and the input flow signal have been calculated for both the non-stenosed and the stenosed bifurcation. Both from the results of the velocity fields and the transfer functions, it can be concluded that the main differences between the flow fields in the non-stenosed and the stenosed bifurcation can be found in an area with high velocity and in a shear layer, which is located at the border between a region with low shear rates at the non-divider wall and a region with high shear rates at the divider wall. The values of the transfer function at these locations seem to be useful for the characterization of the influence of the stenosis.