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Transient flow analysis of opening hinged/sliding door
Get PDFMost people spend the majority of a day indoors where temperature and air quality have a big impact on their work performance, comfort and health. To be able to control the spread of diseases in indoor environments it is crucial to understand the indoor air flows. An important part of this is to look at the different factors which effects the way the air moves. Understanding of air flow and mass exchange by the opening of a door is beneficial for estimation of pollutant transport and this makes us able to better predict and control desired indoor environment. In this thesis Numerical simulations were performed to solve coupled of mass, momentum and energy transport equations. The focus of this work was the usage of the overset mesh for moving rigid boundaries and two-equation turbulence models towards understanding the effects of door opening speed and time, thermal effects, and turbulence models. This work is also very relevant to the present pandemic situation. The simulations involve three different types of doors. One hinged, one sliding and one elevator door. In addition to the different door types, it has also been performed simulations with different opening times and thermal effect. Besides how the door moves the geometry and boundary conditions are the same for each case. To track the air exchange between the two rooms sulfur hexafluoride (SF6) tracer gas was used.
To verify the CFD methods used in the thesis a test case that is similar in both physics and geometry to the simulations previously reported by the other researchers in the literature have been reproduced. When reviewing the flow field and the velocity It is evident from the comparison that the solutions from the reproduced model agree well with the literature. The comparison of the opening and closing door motions times for the hinged and the sliding door shows that the total time of the motion affects the airflow. Lower opening time creates a higher velocity and more exchange between the two rooms.
For the non-thermal simulations visual comparison was done by monitoring the mass fraction of SF6 in a scalar scene and the velocity with the use of the Line Integral Convolution (LIC) in the vector scene. The results clearly shows that the hinged door creates most exchange of air and creates the most velocity in the airflow. The sliding door and the elevator door has less effect. The cumulative mass of SF6 exchanged through the door opening was also monitored and showed that the hinged door has the biggest impact. Time snaps at different timesteps of velocity and mass flux shows the same trend with the biggest effect from the hinged door.
For the thermal cases is also shown that the hinged door creates most exchange of air and creates the most velocity in the airflow. Still the sliding door and the elevator door seems to be most affected by the temperature. Meaning that these cases show a clearer difference compared to the non- thermal case. The cumulative mass of SF6 exchanged through the door opening is also closer to hinged door. The time snaps at different timesteps shows the same trend with the most change in velocity and mass flux for the elevator and the sliding door. The hinged door is also seen the dominant force for the thermal case but it is seen clearly that the temperature difference effects the airflow.
It can be concluded that STAR CMM+ is a powerful tool and that the overset mesh works well for the purpose of simulating solid movements. Using the overset mesh is a demanding process in the start-up phase, but this type of CFD simulations provide valuable information for estimation of pollutant transport and prediction of desired indoor environment. The results are also relevant for energy use, the thermal simulations of the cold storage room in particular.publishedVersio
Transient flow analysis of opening hinged/sliding door
No full textMost people spend the majority of a day indoors where temperature and air quality have a big impact on their work performance, comfort and health. To be able to control the spread of diseases in indoor environments it is crucial to understand the indoor air flows. An important part of this is to look at the different factors which effects the way the air moves. Understanding of air flow and mass exchange by the opening of a door is beneficial for estimation of pollutant transport and this makes us able to better predict and control desired indoor environment. In this thesis Numerical simulations were performed to solve coupled of mass, momentum and energy transport equations. The focus of this work was the usage of the overset mesh for moving rigid boundaries and two-equation turbulence models towards understanding the effects of door opening speed and time, thermal effects, and turbulence models. This work is also very relevant to the present pandemic situation. The simulations involve three different types of doors. One hinged, one sliding and one elevator door. In addition to the different door types, it has also been performed simulations with different opening times and thermal effect. Besides how the door moves the geometry and boundary conditions are the same for each case. To track the air exchange between the two rooms sulfur hexafluoride (SF6) tracer gas was used.
To verify the CFD methods used in the thesis a test case that is similar in both physics and geometry to the simulations previously reported by the other researchers in the literature have been reproduced. When reviewing the flow field and the velocity It is evident from the comparison that the solutions from the reproduced model agree well with the literature. The comparison of the opening and closing door motions times for the hinged and the sliding door shows that the total time of the motion affects the airflow. Lower opening time creates a higher velocity and more exchange between the two rooms.
For the non-thermal simulations visual comparison was done by monitoring the mass fraction of SF6 in a scalar scene and the velocity with the use of the Line Integral Convolution (LIC) in the vector scene. The results clearly shows that the hinged door creates most exchange of air and creates the most velocity in the airflow. The sliding door and the elevator door has less effect. The cumulative mass of SF6 exchanged through the door opening was also monitored and showed that the hinged door has the biggest impact. Time snaps at different timesteps of velocity and mass flux shows the same trend with the biggest effect from the hinged door.
For the thermal cases is also shown that the hinged door creates most exchange of air and creates the most velocity in the airflow. Still the sliding door and the elevator door seems to be most affected by the temperature. Meaning that these cases show a clearer difference compared to the non- thermal case. The cumulative mass of SF6 exchanged through the door opening is also closer to hinged door. The time snaps at different timesteps shows the same trend with the most change in velocity and mass flux for the elevator and the sliding door. The hinged door is also seen the dominant force for the thermal case but it is seen clearly that the temperature difference effects the airflow.
It can be concluded that STAR CMM+ is a powerful tool and that the overset mesh works well for the purpose of simulating solid movements. Using the overset mesh is a demanding process in the start-up phase, but this type of CFD simulations provide valuable information for estimation of pollutant transport and prediction of desired indoor environment. The results are also relevant for energy use, the thermal simulations of the cold storage room in particular
Unsteady flow analysis of hinged and sliding door openings
Get PDFExisting thermal condition and indoor air quality have a big impact on our work performance, comfort, and health in an indoor environment. Apart from many other parameters, door motions and human movements play crucial role in mass and thermal exchange affecting safety and/or energy management issues in various situations. An isolation room in a hospital setup, for instance, helps to protect patients and staff against the risk of infection by airborne pathogens. Another example is cold storage room facilities, where temperature and moisture control are the key parameters for an optimal operation and energy usage. In this study, we present a transient flow analysis of door motions in indoor environment. The flow physics is resolved by solving 3D compressible RANS (Reynolds-averaged Navier-Stokes) equations together with the energy and species transport equations and two-equation turbulence models utilizing an overset mesh strategy to address the rigid body motion of doors in a relevant fluid domain involving air and sulfur hexafluoride (SF6). Simulations are performed for three different types of doors, namely a hinged door, a two-way sliding door, and a sliding door considering door opening and closing phases. Transient flow-field data through the door opening area have been processed and a comparative analysis is performed considering the mass flux of the constituents, normal velocity, cumulative mass exchange through the different doors
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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