Zefiro e' stato uno strumento molto utile e di qualita' per la simulazione del sistema cardiovascolare umano mediante home-brewed software. Se possibile mantenere il monte ore assegnato l'anno scorso sarebbe ottimo (ovviamente con maggior attenzione a non sforare il monte ore allocato). Grazie infinite e cordiali saluti, Gianluigi Rozza
Understanding fluid dynamics in biomedical configurations can be a valuable tool in the improvement of prosthetic devices such as coronary artery bypass grafts (CABGs). Coronary artery bypass grafting is a surgical procedure to create new paths around narrowed coronary arteries to restore sufficient blood flow to the heart. In this project we have performed several computational fluid dynamics studies on a large number of patient-specific configurations, representative of several different surgeries, properly reconstructed from medical data. Moreover, the study of parametrized patient-specific configurations is of remarkable clinical interest, considering both physical (such as Reynolds numbers, flow rates, etc.) and geometrical parameters (related both to native coronary artery disease and surgical procedure). Reduced-order methods have been devised in the past to exploit a parametrized formulation and decouple the computation between an offline phase and an online stage. During the offline stage several high-fidelity approximations of the problem at hand (unsteady Navier-Stokes equations) are solved, for carefully selected values of the parameters, in order to select the most representative basis functions and store them in a database. HPC clusters are usually needed in this phase, especially when considering complex configurations such as the ones of patient-specific CABGs. This stage motivates the use of computational resources on Zefiro. Instead, during the online stage, which can be performed on a laptop, the database is queried and an approximation of the blood flow (and also of the pressure, thanks to the methodological improvements proposed in [1]) is obtained at sensibly reduced computational costs. Several results on patient-specific geometries have been obtained in this framework and presented in [2], employing the parametrized formulation to show for instance how the behavior of the graft changes for increased graft flow (rest vs exercise conditions), different disease (critical or non-critical cases) and surgeries (local features of the anastomosis).
[1] Francesco Ballarin, Andrea Manzoni, Alfio Quarteroni and Gianluigi Rozza. Supremizer stabilization of POD-Galerkin approximation of parametrized steady incompressible Navier-Stokes equations. International Journal for Numerical Methods in Engineering (in press), 2014 [2] Francesco Ballarin, Elena Faggiano, Andrea Manzoni, Alfio Quarteroni, Gianluigi Rozza, Roberto Scrofani. A reduced-order computational framework for patient-specific coronary artery bypass grafts: data acquisition, shape parametrization, computational reduction, in preparation, 2015.
Prof. Ing. Gianluigi ROZZA, PhD Associate Professor in Numerical Analysis
SISSA MathLab International School for Advanced Studies Scuola Internazionale Superiore di Studi Avanzati Office A-435, Via Bonomea 265, 34136 Trieste, Italy
Ph.: +39 040 3787 451 (dir); Fax: +39 040 3787 528 Email: gianluigi.rozza@sissa.it PEC: gianluigi.rozza@ingpec.eu Web: http://people.sissa.it/~grozza