Abdominal aortic aneurysms (AAAs) rupture is one of the main causes of death in the world. This is a very complex phenomenon that usually occurs "without previous warning". Currently, criteria to assess the aneurysm rupture risk (peak diameter and growth rate) can not be considered as reliable indicators. In order to improve the predicting of AAA rupture risk, the theoretical foundation of a simple method, where the main geometric parameters of aneurysms have been linked into six biomechanical factors, which have been combined to obtain a dimensionless rupture risk index, RI(t), is presented in this work. This quantitative indicator, which has been implemented in a tool, is easy to understand, it allows estimating the aneurysms rupture risks, it is expected to be able to identify the one that ruptures even when its peak diameter is less than the threshold value and identify those cases where the rupture should not occur and according to the maximum diameter, the patient is submitted to surgical procedure. The method was validated, preliminarily, with a clinical case and other three cases from the literature. Based on these initial results of the validation test, a broader prospective randomised control study has been carried out with two hundred and one patients at the Clinic Hospital of Valladolid-Spain, which were submitted to surgical repair treatment (EVAR). The results of this study shown that it is possible to carry out a clinical assessment of the AAA rupture risk through its geometric parameters and that the most important geometric biomechanical factors are the deformation rate and saccular index.

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Abstract. The drag reduction by polymer addition is wide interest in several areas. It has been shown that the polymer addition cushions the dissipative effects in turbulent flows. The main objective of this work is to establish a methodology for the numerical simulation of viscoelastic fluid through internal subroutines implemented in the Fluent code, via UDF. The validation of this methodology is made for the laminar flow regime case in pipeline. To describe the viscoelastic effect, it was used the Finitely Extensible Nonlinear Elastic model closing with Peterlin model. To taking in account the viscous effects 50 Re 2000 values were used. In addition, for the polymer concentration analysis it was used values which depend on the polymers molecular weight and the solution concentration that ranged from 0 Cw 20. The molecular elasticity and extensibility were maintained at constant values. The results showed that the addition of polymers regardless of their molecular weight in laminar flow regime causes no change in power dissipation. This result, which is consistent with the literature, is a significant advance in defining a credible and appropriate methodology to viscoelastic fluid flow study by UDF implementation of constituent models that characterize these fluids.