Computational Fluid Dynamic and Magnetic Resonance Analyses of Flow Distribution Between the Lungs After Total Cavopulmonary Connection

Total cavopulmonary connection is a surgical procedure adopted to treat complex congenital malformations of the right heart. It consists basically in a connection of both venae cavae directly to the right pulmonary artery. In this paper a three-dimensional model of this connection is presented, which is based on in vivo measurements performed by means of magnetic resonance. The model was developed by means of computational fluid dynamics techniques, namely the finite element method. The aim of this study was to verify the capability of such a model to predict the distribution of the blood flow into the pulmonary arteries, by comparison with in vivo velocity measurements. Different simulations were performed on a single clinical case to test the sensitivity of the model to different boundary conditions, in terms of inlet velocity profiles as well as outlet pressure levels. Results showed that the flow distribution between the lungs is slightly affected by the shape of inlet velocity profiles, whereas it is influenced by different pressure levels to a greater extent

Slag waste incorporation in high early strength concrete as cement replacement: Environmental impact and influence on hydration & durability attributes

This paper investigates the effects of incorporating slag waste (Ground Granulated Blast Furnace Slag; GGBS) as cement replacement in high early strength concrete. GGBS was used in various replacement ratios and resulting properties of the developed concretes were evaluated. Compressive strength, heat of hydration and shrinkage were determined for evaluating hydration attributes while chloride penetrability and carbonation resistance were investigated for studying the durability-related characteristics of the resulting concretes. The optimum ratio of GGBS as SCM has been determined, in this study, as 30% at which there is merely an average strength decline of 11% while reducing the total carbon dioxide emissions by 30%. Similarly, at this replacement level, the decreased chloride ion penetrability (15%) and higher carbonation resistance (3%) further encourage its use in precast concrete incorporating (HESC). Finally, the beneficial effects of using slag waste in concrete were quantified by determining associated CO2 emissions. It is concluded that slag incorporation in concrete significantly reduces the CO2 emissions, (up to 68%) depending on the cement replacement level, thus promoting green construction and sustainable development

Partitioned fluid-solid coupling for cardiovascular blood flow: validation study of pressure-driven fluid-domain deformation.

The Karlsruhe Heart Model (KaHMo) is a patient-specific simulation tool for a three-dimensional blood flow evaluation inside the human heart. Whereas KaHMo MRT is based on geometry movement identified from MRT data, KaHMo FSI allows the consideration of structural properties and the analysis of FSI. Previous investigations by Oertel et al. have shown the ability of KaHMo to gain insight into different intra-ventricular fluid mechanics of both healthy and diseased hearts. However, the in vivo validation of the highly dynamic cavity flow pattern has been a challenging task in recent years. As a first step, the focus of this study is on an artificial ventricular experiment, derived from real heart anatomy. Fluid domain deformation and intra-ventricular flow dynamics are enforced by an outer surface pressure distribution. The pure geometrical representation of KaHMo MRT can now be complemented by constitutive properties, pressure forces, and interaction effects using KaHMo FSI's partitioned code-coupling approach. For the first time, fluid domain deformation and intra-ventricular flow of KaHMo FSI has been compared with experimental data. With a good overall agreement, the proof of KaHMo's validity represents an important step from feasibility study toward patient-specific analysis