Physically consistent simulation of transport of inertial particles in porous media

A new numerical approach is presented for simulating the movement of test particles suspended in an incompressible fluid flowing through a porous matrix. This two-phase particle-laden flow is based on the Navier-Stokes equations for incompressible fluid flow and equations of motion for the individual particles in which Stokes drag is dominant. The Immersed Boundary method is applied to incorporate the geometric complexity of the porous medium. A symmetry-preserving finite volume discretization method in combination with a volume penalization method resolves the flow within the porous material. The new Lagrangian particle tracking is such that for mass-less test particles no (numerical) collision with the coarsely represented porous medium occurs at any spatial resolution

Simulation of impaction filtration of aerosol droplets in porous media

We report on the development of a method to simulate from first principles the particle filtration efficiency of filters that are composed of structured porous media. We assume that the ratio of particle density to the fluid density is high. We concentrate on the motion of the particles in a laminar flow and quantify the role of inertial effects on the filtration of an ensemble of particles. We adopt the Euler-Lagrange approach, distinguishing a flow field in which the motion of a large number of discrete particles is simulated. We associate filtration with the deterministic collision of inertial particles with solid elements of the structured porous medium. To underpin the physical `consistency' of deterministic particle filtration, we investigate to what extent the particle tracking algorithm ensures that mass-less test-particles will not be captured by the structured porous filter at all. This element of the algorithm is essential in order to distinguish physical filtration by inertial effects from unwanted numerical filtration, due to the finite spatial resolution of the gas flow. We consider filtration of particles whose motion is governed by Stokes drag and determine the filtration efficiency in a range of Stokes relaxation times. An exponential decay of the number of particles with time is observed

Aerosol dynamics in porous media

In this thesis, a computational model was developed for the simulation of aerosol formation through nucleation, followed by condensation and evaporation and filtration by porous material. Understanding aerosol dynamics in porous media can help improving engineering models that are used in various industrial, medical and environmental applications. Within the Euler-Lagrange framework of modeling two-phase flow, the trajectories of individual aerosol droplets, as well as the heat and mass transfer with their surroundings, were evaluated in velocity, temperature and species concentration fields that were computed by applying the immersed boundary (IB) method to flow in complex domains.\ud \ud Following ‘one-way’ coupling approach, a ‘no-slip consistent’ particle tracking method was developed, formulated entirely in terms of the phase-indicator function related to the inner structure of the filter. This method was applied to study the filtration characteristics of structured porous media in 3D and of a realistic porous material, illustrating the potential of the approach in terms of predicting such macroscopic aspects based on pore-resolved flow. Another way of controlling the aerosol that eventually emanates from a process can be achieved by controlling the conditions at which the aerosol forms. This involves coupling of the fluid flow with the process of nucleation and subsequent evolution of the aerosol properties due to evaporation and condensation. We adapted the classical nucleation theory (CNT) which links locally supersaturated vapor state to the nucleation of so-called ‘critical clusters’ and considered the nucleation rate from CNT as the probability per unit of time and volume to generate such critical clusters. This computational model was applied to a laminar flow in a channel between two parallel plates. Nucleation was initiated by rapid cooling of air saturated with dibutylphthalate vapor at the inflow of the channel. This approach illustrates a first application of the Euler-Lagrange framework to aerosol formation and presents aspects such as the evolving droplet size distribution and characteristics of the aerosol as it emanates from the end of the channel. It is a basis for studying the dependence of the aerosol formation process on important parameters such as the temperature, the cooling rate and the flow velocity

The Implementation of the WHO Mental Health Gap Intervention Guide (mhGAP-IG) in Ukraine, Armenia, Georgia and Kyrgyz Republic

Despite the increasing burden of mental disorders, a lot of people worldwide suffer a gap in receiving necessary care in these countries. To close this gap, the WHO has developed mhGAP training modules aimed at scaling up mental health and substance use disorders services, especially in low- and middle-income countries. This article presents the experience of implementing the Mental Health Gap Action Programme (mhGAP) in Ukraine, Armenia, Georgia, and Kyrgyz Republic. Data were gathered from an electronic questionnaire administered to representatives from higher educational institutions where the Mental Health Gap Action Programme Intervention Guide (mhGAP-IG) was implemented in existing curricula for medical students, interns, and residents in family medicine and neurology, practicing physicians, and master’s program in mental health students. More than 700 students went through the programs that provided the feedback. Evaluations of program effectiveness mainly involved standard discipline tests or pre- and post-tests proposed in the mhGAP trainer manual. This finding suggested that mhGAP-IG can be successfully adapted and implemented both on undergraduate and on postgraduate education levels and among medical and nonmedical specialists. Future evaluations need to more definitively assess the clinical effectiveness of mhGAP-IG implementation

Effect of evaporation and condensation on droplet size distribution in turbulence

The interaction of droplets that undergo phase transition with a turbulent flow is encountered in many areas of engineering and atmospheric science as described in (Lanotte et al., 2008). In the context of cloud physics the evaporation and condensation of water vapor from and to the droplets is the governing process for the growth of the droplets from sub micron size up to a size of around 20 µm, after which they grow mostly by coalescence until they become large enough to fall as rain drops under gravity. Much pioneering work has been done in (Luo et al., 2008; Lanotte et al., 2008; Sidin et al., 2009) on the theoretical and numerical investigation of the influence of turbulence on evaporation and condensation associated with aerosol droplets. In this paper we consider the situation of water droplets undergoing phase change and moving in air. Air also advects the vapor concentration field. We compute the natural size distribution of the droplets that arises as a result of the interaction between the droplets and the transporting turbulent flow. We assume the turbulent flow to be homogeneous and isotropic. We will perform DNS of the velocity field and the passively advected vapor and temperature field. The droplet trajectories are computed time-accurately in a domain with periodic boundary condition

The Implementation of the WHO Mental Health Gap Intervention Guide (mhGAP-IG) in Ukraine, Armenia, Georgia and Kyrgyz Republic

Despite the increasing burden of mental disorders, a lot of people worldwide suffer a gap in receiving necessary care in these countries. To close this gap, the WHO has developed mhGAP training modules aimed at scaling up mental health and substance use disorders services, especially in low- and middle-income countries. This article presents the experience of implementing the Mental Health Gap Action Programme (mhGAP) in Ukraine, Armenia, Georgia, and Kyrgyz Republic. Data were gathered from an electronic questionnaire administered to representatives from higher educational institutions where the Mental Health Gap Action Programme Intervention Guide (mhGAP-IG) was implemented in existing curricula for medical students, interns, and residents in family medicine and neurology, practicing physicians, and master’s program in mental health students. More than 700 students went through the programs that provided the feedback. Evaluations of program effectiveness mainly involved standard discipline tests or pre- and post-tests proposed in the mhGAP trainer manual. This finding suggested that mhGAP-IG can be successfully adapted and implemented both on undergraduate and on postgraduate education levels and among medical and nonmedical specialists. Future evaluations need to more definitively assess the clinical effectiveness of mhGAP-IG implementation

WHO Mental Health Gap Action Programme Intervention Guide (mhGAP-IG): the first pre-service training study

Abstract Background Despite the increasing burden of mental, neurological, and substance use (MNS) disorders, a significant treatment gap for these disorders continues to exist across the world, and especially in low- and middle-income countries. To bridge the treatment gap, the World Health Organization developed and launched the Mental Health Gap Action Programme (mhGAP) and the mhGAP Intervention Guide (mhGAP-IG) to help train non-specialists to deliver care. Although the mhGAP-IG has been used in more than 100 countries for in-service training, its implementation in pre-service training, that is, training prior to entering caregiver roles, is very limited. Aim of the study The aim of this study was to collect and present information about the global experience of academic institutions that have integrated WHO’s mhGAP-IG into pre-service training. Methods A descriptive cross-sectional study was conducted using an electronic questionnaire, from December 2018 to June 2019. Results Altogether, eleven academic institutions across nine countries (Mexico, Nigeria, Liberia, Sierra Leone, Somaliland, Armenia, Georgia, Ukraine and Kyrgyzstan) participated in this study. Five of the institutions have introduced the mhGAP-IG by revising existing curricula, three by developing new training programmes, and three have used both approaches. A lack of financial resources, a lack of support from institutional leadership, and resistance from some faculty members were the main obstacles to introducing this programme. Most of the institutions have used the mhGAP-IG to train medical students, while some have used it to train medical interns and residents (in neurology or family medicine) and nursing students. Use of the mhGAP-IG in pre-service training has led to improved knowledge and skills to manage mental health conditions. A majority of students and teaching instructors were highly satisfied with the mhGAP-IG. Conclusions This study, for the first time, has collected evidence about the use of WHO’s mhGAP-IG in pre-service training in several countries. It demonstrates that the mhGAP-IG can be successfully implemented to train a future cadre of medical doctors and health nurses