Klaus Affeld

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The interaction of flow and thrombus generation often is a crucial question for the engineer working in the field of artificial organs. However, this interaction is only incompletely known, and quantitative data under well-defined experimental conditions are especially rare. These can be attained with the stagnation point flow chamber. This flow model(More)
Between one-fourth and one-third of the energy in rowing is lost to the flow of water around the blade which decreases efficiency, i.e., the ratio of effective energy to expended energy. Hitherto the assessment of this hydrodynamic rowing efficiency was difficult and could not be achieved as a function of rowing angle and time. By recording the path of the(More)
The aim of this study was to determine a method for the numerical estimation of blood damage. Normally, human or animal blood is used for in vitro evaluation of lysis by artificial organs. However, blood has some disadvantages: large biological variability and different initial test conditions lead to nonreproducible test results. For that reason, it would(More)
Computational fluid dynamics (CFD) methods based on three-dimensional (3D) vessel reconstructions have recently been shown to provide prognostically relevant hemodynamic data. However, the geometry reconstruction and the assessment of clinically relevant hemodynamic parameters may depend on the used imaging modality. In this study, the silicon model of the(More)
Presently available hydrocephalus valves still are not perfect. There are two major drawbacks: They have a tendency to clog and do not take into account the posture of the patient. The latter results in an intracranial pressure which is either too high or too low. To avoid these problems a new valve was designed which is described in this article. It(More)
The carotid artery is of special interest for the pathologist because of its frequent depositions, and for the fluidmechanician because of its complex flow properties. However, there is a distinct lack in current knowledge of its geometry. Therefore, a vessel cast study was undertaken. At post mortem, the arteries are excised and filled with a special resin(More)
A study was conducted to measure in vitro the procoagulant properties of platelets induced by flow through Carbomedics bileaflet and Bjork–Shiley monoleaflet mechanical heart valves (MHVs). Valves were mounted in a left ventricular assist device, and platelets were circulated through them under pulsatile flow. Platelet activation states (PAS) were measured(More)
AIMS Wall shear stress (WSS) may induce local remodeling of the vascular wall and the WSS pattern in turn depends on vascular geometry. We aimed to elucidate the impact of side-branches on local WSS. METHODS AND RESULTS Steady numerical flow simulation studies were performed in three-dimensional reconstructed right coronary artery (RCA) trees. RCA from(More)
Platelet deposition in resting blood is well researched and understood. However, the influence of hemodynamic parameters such as wall shear rate is less clear. Clinical experience and experiments show an interaction between flow and platelet deposition. But a complete understanding of the flow influence and hence a quantification has not yet been achieved.(More)
The carotid artery bifurcation is of special interest to both the pathologist because of its frequent atherosclerotic depositions, and to the fluidmechanicist because of its complex flow properties. However, current knowledge is incomplete regarding the level and position of atherosclerotic plaques in the carotid bifurcation and their quantitative(More)