ISBN 9783843912600

978-3-8439-1260-0, Reihe Ingenieurwissenschaften

Markus Probst
Robust Shape Optimization for Incompressible Flow of Shear-Thinning Fluids - Application to Hemolysis Reduction in Medical Devices and to Design of Profile Extrusion Dies

245 Seiten, Dissertation Rheinisch-Westfälische Technische Hochschule Aachen (2013), Softcover, A5

Zusammenfassung / Abstract

For both medical devices and profile extrusion dies, the interest in the automation of the design process by numerical methods stems from the high development costs caused by the construction and evaluation of prototypes. In this thesis, the automation was achieved by coupling Computational Fluid Dynamics methods with geometry deformation methods and optimization algorithms. Particular focus was laid on investigating the influence of three different aspects on the setup and the outcome of the design process: the constitutive model, the objective function, and the geometry representation. Furthermore, automatic differentiation was validated as a method to assess the robustness of optimal shapes to parameters inherent to the employed optimization framework.Two significant aspects of this work are that shape optimization was carried out for complex geometries using highly resolved, three-dimensional fluid simulations and that, in case of a floor skirting profile extrusion die, the computed shaped was manufactured and its performance was assessed in practice.

As a conclusion of the assessment, it is advisable to start the die optimization from a pre-optimized shape, to optimize the die region by region in consecutive steps, and to incorporate a measure of the overall balance between the main sections of the profile in the objective function. Regarding the optimization of the Micromed DeBakey blood pump, the results of this thesis suggest that a positive effect on both hydraulic and hematologic performance of the pump is obtained by reducing the gap width between impeller and diffuser.