Laminar forced convection flow over a backward facing step using nanofluids

Reverse flow regions in three-dimensional backward-facing step flow

UNLABELLED Residents of low-income multifamily housing can have elevated exposures to multiple environmental pollutants known to influence asthma. Simulation models can characterize the health implications of changing indoor concentrations, but quantifying the influence of interventions on concentrations is challenging given complex airflow and source characteristics. In this study, we simulated concentrations in a prototype multifamily building using CONTAM, a multizone airflow and contaminant transport program. Contaminants modeled included PM(2.5) and NO(2) , and parameters included stove use, presence and operability of exhaust fans, smoking, unit level, and building leakiness. We developed regression models to explain variability in CONTAM outputs for individual sources, in a manner that could be utilized in simulation modeling of health outcomes. To evaluate our models, we generated a database of 1000 simulated households with characteristics consistent with Boston public housing developments and residents and compared the predicted levels of NO(2) and PM(2.5) and their correlates with the literature. Our analyses demonstrated that CONTAM outputs could be readily explained by available parameters (R(2) between 0.89 and 0.98 across models), but that one-compartment box models would mischaracterize concentrations and source contributions. Our study quantifies the key drivers for indoor concentrations in multifamily housing and helps to identify opportunities for interventions. PRACTICAL IMPLICATIONS Many low-income urban asthmatics live in multifamily housing that may be amenable to ventilation-related interventions such as weatherization or air sealing, wall and ceiling hole repairs, and exhaust fan installation or repair, but such interventions must be designed carefully given their cost and their offsetting effects on energy savings as well as indoor and outdoor pollutants. We developed models to take into account the complex behavior of airflow patterns in multifamily buildings, which can be used to identify and evaluate environmental and non-environmental interventions targeting indoor air pollutants which can trigger asthma exacerbations.

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Simulating indoor concentrations of NO(2) and PM(2.5) in multifamily housing for use in health-based intervention modeling.

https://dspace.stir.ac.uk/bitstream/1893/27559/1/Okello_pre_publication.pdf

Women and girls in resource poor countries experience much greater exposure to household air pollutants than men: Results from Uganda and Ethiopia.

A comprehensive survey of the literature in the area of numerical heat transfer (NHT) published between 2000 and 2009 has been conducted Due to the immenseness of the literature volume, the survey

Literature Survey of Numerical Heat Transfer (2000–2009): Part II

Numerical solutions are obtained for fluid flow and heat transfer downstream of a 3-D backward-facing step within a duct. A heat flux is applied along the bottom surface downstream of the step. The dimensions downstream of the step are 30H 2 12H 2 H, where H = 1 cm (channel height); uniform flow enters a 20H 2 12H 2 H/2 channel upstream of the step. The numerical model is based on a modified Petrov-Galerkin finite element technique that incorporates sparse storage solution with mass lumping. A projection algorithm is used to solve the primitive equations of motion. Upper and lower recirculation zones in the 3-D solutions are very different from 2-D results. Solutions obtained for Re = 400, 800, and 1200 are presented that illustrate changing recirculation and vortex zones. A time history shows the evolution of velocities along the centerline at Re = 800. Bulk Nusselt numbers converge to experimental values downstream of the step where the flow returns to a fully developed parabolic profile.

Convective heat transfer downstream of a 3-d backward-facing step

Fluid Flow Fundamentals Contaminant Sources Assessment Criteria Simple Modeling Techniques Dynamics of Particles, Gases and Vapors Numerical Modeling - Conventional Techniques Numerical Modeling - Advanced Techniques Turbulence Modeling Homeland Security Issues.

Modeling Indoor Air Pollution

A parallel h-adaptive finite element model for atmospheric transport prediction

A two-equation turbulence closure model (k-{omega}) using an h-adaptive grid technique and finite element method (FEM) has been developed to simulate low Mach flow and heat transfer. These flows are applicable to many flows in engineering and environmental sciences. Of particular interest in the engineering modeling areas are: combustion, solidification, and heat exchanger design. Flows for indoor air quality modeling and atmospheric pollution transport are typical types of environmental flows modeled with this method. The numerical method is based on a hybrid finite element model using an equal-order projection process. The model includes thermal and species transport, localized mesh refinement (h-adaptive) and Petrov-Galerkin weighting for the stabilizing the advection. This work develops the continuum model of a two-equation turbulence closure method. The fractional step solution method is stated along with the h-adaptive grid method (Carrington and Pepper, 2002). Solutions are presented for 2d flow over a backward-facing step.

David B. Carrington

Papers

Convective heat transfer downstream of a 3-d backward-facing step

Modeling Indoor Air Pollution

A parallel h-adaptive finite element model for atmospheric transport prediction

An h-adaptive finite element method for turbulent heat transfer

Fluid Flow Fundamentals