Markus Probst

Interactive Blood Damage Analysis for Ventricular Assist Devices

Ventricular Assist Devices (VADs) support the heart in its vital task of maintaining circulation in the human body when the heart alone is not able to maintain a sufficient flow rate due to illness or degenerative diseases. However, the engineering of these devices is a highly demanding task. Advanced modeling methods and computer simulations allow the investigation of the fluid flow inside such a device and in particular of potential blood damage. In this paper we present a set of visualization methods which have been designed to specifically support the analysis of a tensor-based blood damage prediction model. This model is based on the tracing of particles through the VAD, for each of which the cumulative blood damage can be computed. The models tensor output approximates a single blood cells deformation in the flow field. The tensor and derived scalar data are subsequently visualized using techniques based on icons, particle visualization, and function plotting. All these techniques are accessible through a Virtual Reality-based user interface, which features not only stereoscopic rendering but also natural interaction with the complex three-dimensional data. To illustrate the effectiveness of these visualization methods, we present the results of an analysis session that was performed by domain experts for a specific data set for the MicroMed DeBakey VAD.

Performance analysis and tuning of the XNS CFD solver on Blue Gene/L

The xns computational fluid dynamics code was successfully running on Blue Gene/L, however, its scalability was unsatisfactory until the first Julich BlueGene/L Scaling Workshop provided an opportunity for the application developers and performance analysts to start working together. Investigation of solver performance pin-pointed a communication bottleneck that appeared with approximately 900 processes, and subsequent remediation allowed the application to continue scaling with a four-fold simulation performance improvement at 4,096 processes. This experience also validated the scalasca performance analysis toolset, when working with a complex application at large scale, and helped direct the development of more comprehensive analyses. Performance properties have now been incorporated to automatically quantify point-to-point synchronisation time and wait states in scan operations, both of which were significant for xns on BlueGene/L.

On the Influence of Constitutive Models on Shape Optimization for Artificial Blood Pumps

We report on a shape optimization framework that couples a highlyparallel finite element solver with a geometric kernel and different optimization algorithms. The entire optimization framework is transformed with automatic differentiation techniques, and the derivative code is employed to compute derivatives of the optimal shapes with respect to viscosity. This methodology provides a powerful tool to investigate the necessity of intricate constitutive models by taking derivatives with respect to model parameters

Design methodology for modular tools

Serving individual customer needs at reasonable prices can be a profitable target market in high-wage countries. The dilemma between scale and scope-oriented production is one major research topic within the Cluster of Excellence “Integrative Production Technology for High-Wage Countries” at the RWTH Aachen University. One main objective of this project is to bridge the existing gap between individual manufacturing and mass production. Modularization is a widely accepted approach in tool-based manufacturing processes. In this paper, we propose a flexible design methodology for modular tools and dies. The methodology will assist the design engineer in setting up a series of modularized tools in a conceptually closed manner. The described methodology covers modularization in a broad sense, i.e. it includes hardware modularization as well as modularization of the construction process. The methodology consists of three phases: initiation, analysis and design phase.