Laser Doppler Anemometry Study of the Flow in a Blood Filter

Damage to red blood cells can be induced chemically, by osmosis or mechanically. The fluid mechanical effect can be related to the device design, its surface characteristics and to the degree of flow disturbance or turbulence caused by the device. Is generally accepted that the presence of high turbulent shear stresses generated in the flow fields of artificial devices are partially responsible for the levels of red blood cells destruction, or hemolysis. Investigating the effect of turbulent shear stress on hemolysis is of prime importance to research work related to artificial devices. Hemolysis is a function of the shear stresses magnitude acting on blood cells and their exposure time to the shear stresses. The present work presents the use of two techniques used to study the flow in an arterial blood filter. The general structure of the flow field was analyzed using the dye injection technique. A laser Doppler anemometer was used to measure two orthogonal velocity components and their fluctuations, which were used to determine the turbulent shear stresses. The exposure time was calculated and used in conjunction with the turbulent shear stresses to estimate the hemoglobin released by the red blood cells.