Numerical Efficiency Assessment of IB-LB Method for 3D Pore-Scale Modeling of Flow and Transport

International audienceIn many earth science and environmental problems, the fluid-structure interactions can affect the hydrodynamics properties of the porous medium via the spatial evolution of its solid matrix. A significant insight into these properties can be obtained from pore-scale simulations. Using a 3D pore-scale domain with moving walls, we proposed in this paper a comparison of the numerical accuracy between different approaches in regard to flow and reactive transport. Two direct-forcing immersed boundary (IB) models coupled with lattice Boltzmann method (LBM) are evaluated for the flow calculation against an analytical solution. The IB-LBM showed improvement compared to the classical and interpolated bounce-back lattice Boltzmann model. Concerning the reactive transport, the most accurate IB-LB method was coupled with two non-boundary conforming finite volume methods (volume of fluid and reconstruction). The comparative study performed with different mesh sizes and Damkohler numbers demonstrates better results for the reconstruction method

Maternal occupation during pregnancy, birth weight, and length of gestation: combined analysis of 13 European birth cohorts

Objectives We assessed whether maternal employment during pregnancy overall and in selected occupational sectors - is associated with birth weight, small for gestational age (SGA), term low birth weight (LBW), length of gestation, and preterm delivery in a population-based birth cohort design. Methods We used data from >200 000 mother-child pairs enrolled in 13 European birth cohorts and compared employed versus non-employed women. Among employees, we defined groups of occupations representing the main sectors of employment for women where potential reproductive hazards are considered to be present. The comparison group comprised all other employed women not included in the occupational sector being assessed. We performed meta-analyses of cohort-specific estimates and explored heterogeneity. Results Employees had a lower risk of preterm delivery than non-employees [adjusted odds ratio (ORadj) 0.86, 95% confidence interval (95% CI) 0.81-0.91]. Working in most of the occupational sectors studied was not associated with adverse birth outcomes. Being employed as a nurse was associated with lower risk SGA infants (ORadj, 0.91, 95% CI 0.84-0.99) whereas food industry workers had an increased risk of preterm delivery (ORadj 1.50, 95% CI 1.12-2.02). There was little evidence for heterogeneity between cohorts. Conclusions This study suggests that, overall, employment during pregnancy is associated with a reduction in the risk of preterm birth and that work in certain occupations may affect pregnancy outcomes. This exploratory study provides an important platform on which to base further prospective studies focused on the potential consequences of maternal occupational exposures during pregnancy on child development