[Flow in natural and artificial organs and vessels (author's transl)]

After introductory remarks about the flow phenomena in the human body (separation, dead waters, stagnation regions) and the model simularity conditions, the flow behaviour in arterial bifurcations at pulsatile flow are considered; they are accompanied by the formation of dead waters and secondary flows and therefore they give the danger of atherosclerosis. Then the flow pattern at arterio-venous anastomosis is interpreted with regard to the danger of thrombogenesis. At the selected example of ball prosthesis the flow pattern and the pressure loss of artificial heart valves (aortic as well as mitral valves) are described; the special behaviour of ball valves used as mitral valves is discussed critically. Finally in a view of contribution to the question of the flow-induced blood damage, in extended series of basic tests on models (orifices and perforated discs) the rate of hemolysis was measured depending on the flow; the tests were completed by measurements at rolling pumps, atria of a artificial ventricle and other parts. In order to try an explanation for the flow-induced hemolysis one starts from the influence of the hemodynamic shear stresses on the damage of the erythrocytes; hereby the effect of the frequently repeated passages of the red blood cells through a stenosis (e.g. regurgitation) should be taken into account.