POD\u2013Galerkin reduced order methods for combined Navier\u2013Stokes transport equations based on a hybrid FV-FE solver

The purpose of this work is to introduce a novel POD\u2013Galerkin strategy for the semi-implicit hybrid high order finite volume/finite element solver introduced in Berm\ufadez et al. (2014) and Busto et al. (2018). The interest is into the incompressible Navier\u2013Stokes equations coupled with an additional transport equation. The full order model employed in this article makes use of staggered meshes. This feature will be conveyed to the reduced order model leading to the definition of reduced basis spaces in both meshes. The reduced order model presented herein accounts for velocity, pressure, and a transport-related variable. The pressure term at both the full order and the reduced order level is reconstructed making use of a projection method. More precisely, a Poisson equation for pressure is considered within the reduced order model. Results are verified against three-dimensional manufactured test cases. Moreover a modified version of the classical cavity test benchmark including the transport of a species is analysed

Model Order Reduction in Fluid Dynamics: Challenges and Perspectives

This chapter reviews techniques of model reduction of fluid dynamics systems. Fluid systems are known to be difficult to reduce efficiently due to several reasons. First of all, they exhibit strong nonlinearities — which are mainly related either to nonlinear convection terms and/or some geometric variability — that often cannot be treated by simple linearization. Additional difficulties arise when attempting model reduction of unsteady flows, especially when long-term transient behavior needs to be accurately predicted using reduced order models and more complex features, such as turbulence or multiphysics phenomena, have to be taken into consideration. We first discuss some general principles that apply to many parametric model order reduction problems, then we apply them on steady and unsteady viscous flows modelled by the incompressible Navier-Stokes equations. We address questions of inf-sup stability, certification through error estimation, computational issues and — in the unsteady case — long-time stability of the reduced model. Moreover, we provide an extensive list of literature references

Health of men, women, and children in post-trafficking services in Cambodia, Thailand, and Vietnam: an observational cross-sectional study

SummaryBackgroundTrafficking is a crime of global proportions involving extreme forms of exploitation and abuse. Yet little research has been done of the health risks and morbidity patterns for men, women, and children trafficked for various forms of forced labour.MethodsWe carried out face-to-face interviews with a consecutive sample of individuals entering 15 post-trafficking services in Cambodia, Thailand, and Vietnam. We asked participants about living and working conditions, experience of violence, and health outcomes. We measured symptoms of anxiety and depression with the Hopkins Symptoms Checklist and post-traumatic stress disorder with the Harvard Trauma Questionnaire, and used adjusted logistic regression models to estimate the effect of trafficking on these mental health outcomes, controlling for age, sector of exploitation, and time in trafficking.FindingsWe interviewed 1102 people, of whom 1015 reached work destinations. Participants worked in various sectors including sex work (329 [32%]), fishing (275 [27%]), and factories (136 [13%]). 481 (48%) of 1015 experienced physical violence, sexual violence, or both, with 198 (35%) of 566 women and girls reporting sexual violence. 478 (47%) of 1015 participants were threatened and 198 (20%) were locked in a room. 685 (70%) of 985 who had data available worked 7 days per week and 296 (30%) of 989 worked at least 11 hours per day. 222 (22%) of 983 had a serious injury at work. 61·2% (95% CI 58·2–64·2) of participants reported symptom of depression, 42·8% (39·8–45·9) reported symptoms of anxiety, and 38·9% (36·0–42·0) reported symptoms of post-traumatic stress disorder. 5·2% (4·0–6·8) had attempted suicide in the past month. Participants who experienced extremely excessive overtime at work, restricted freedom, bad living conditions, threats, or severe violence were more likely to report symptoms of depression, anxiety, and post-traumatic stress disorder.InterpretationThis is the first health study of a large and diverse sample of men, women, and child survivors of trafficking for various forms of exploitation. Violence and unsafe working conditions were common and psychological morbidity was associated with severity of abuse. Survivors of trafficking need access to health care, especially mental health care.FundingFunding Anesvad Foundation and IOM Development Fund