Direct Numerical Simulation of  turbulent canopy flow

2021 ◽  
Author(s):  
Ganapati Sahoo ◽  
Soumak Bhattacharjee ◽  
Andrey Debolsky ◽  
Evgeny Kadanstev ◽  
Evgeny Mortikov ◽  
...  
Keyword(s):  
Turbulent Flows ◽  
Numerical Study ◽  
Areal Density ◽  
Roughness Sublayer ◽  
Local Anisotropy ◽  
Eddy Covariance Measurements ◽  
Computational Resources ◽  
Turbulence Transport ◽  
The University

<p>Turbulent flows within and above urban and vegetative canopies in the atmospheric boundary layer have profound implications for a variety of important problems in  agricultural  and urban meteorology, such as the spreading of pollens and pollutants. We study such turbulence via Direct Numerical Simulations (DNSs), by using the code developed in (2019 Mortikov),  in which there is a closed channel between two parallel walls and a canopy of constant areal density profile on the lower wall. We impose periodic boundary conditions in the horizontal directions and a no-slip impenetrable boundary condition in the wall-normal direction. For the canopy, we use different formulations of the Forchheimer drag. We assess the role of the canopy on the turbulent flow. In particular, we show the influence of added drag on the mean profiles, balance equations of the second-order moments, and the local anisotropy of the flow.</p><p>We observe that the turbulence transport profile undergoes an abrupt transition at the canopy top and transfer of energy from the roughness sublayer above the canopy to inside the canopy.  <br>The pressure-strain correlation removes energy from the wall-normal fluctuations, which has the least share of the turbulent kinetic energy and distributes it among the other components in the bulk of the canopy. In the inertial range, within and above the canopy, the energy spectra for the streamwise component is steeper than the spanwise and the wall-normal components and is closer to the Kolmogorov -5/3 spectrum as observed in the eddy covariance measurements in the roughness sublayer (2020 Bhattacharjee).</p><p>We thank the DST, CSIR (India), SERC (IISc) for computational resources, the AtMath Collaboration at the University of Helsinki, and ICOS by University of Helsinki for their support. This study was also partially funded by RFBR project number 20-05-00776.</p><p>Reference</p><p>2019, Mortikov, E. V., Glazunov, A. V., & Lykosov, V. N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure–strain correlations, Russian Journal of Numerical Analysis and Mathematical Modelling, 34(2), 119-132. doi: https://doi.org/10.1515/rnam-2019-0010.</p><p>2020, Bhattacharjee S., Pandit R., Vesala T., Mammarella I., Katul G., and Sahoo G. Anisotropy and multifractal analysis of turbulent velocity and temperature in the roughness sublayer of a forested canopy, arXiv:2010.04194.</p>

Collision rate of ice crystals with water droplets in turbulent flows

2018 ◽  
Vol 845 ◽  
pp. 615-641 ◽  
Author(s):  
Aurore Naso ◽  
Jennifer Jucha ◽  
Emmanuel Lévêque ◽  
Alain Pumir
Keyword(s):  
Turbulent Flows ◽  
Stokes Equations ◽  
Numerical Study ◽  
Dominant Role ◽  
Ice Crystals ◽  
Turbulent Regime ◽  
Fluid Inertia ◽  
Collision Rate ◽  
Water Droplets

Riming, the process whereby ice crystals get coated by impacting supercooled liquid droplets, is one of the dominant processes leading to precipitation in mixed-phase clouds. How a settling crystal collides with very small water droplets has been mostly studied in laminar conditions. The present numerical study aims at providing further insight on how turbulent flow motion affects the riming of ice crystals. We model the crystals as narrow oblate ellipsoids, smaller than the Kolmogorov elementary scale. By neglecting the effect of fluid inertia on the motion of the crystals and droplets, and using direct numerical simulations of the Navier–Stokes equations in a moderately turbulent regime, over a range of kinetic energy dissipation $1~\text{cm}^{2}~\text{s}^{-3}\lesssim \unicode[STIX]{x1D700}\lesssim 256~\text{cm}^{2}~\text{s}^{-3}$, we determine the collision rate between disk-shaped ice crystals and very small liquid water droplets. Whereas differential settling plays the dominant role in determining the collision rate at small turbulence intensity, the role of turbulence becomes more important at the large values of $\unicode[STIX]{x1D700}$ simulated, an effect that can be partly attributed to the increased role of inertia. We always find that collisions occur with a large probability on the rim of the ellipsoids, a phenomenon that can be explained to a large extent by kinematic considerations. The difference in the settling velocity of crystals and droplets induces a strong asymmetry in the probability of collision between the faces of the ellipsoids. Our results shed light on the physical mechanisms involved in the riming of ice crystals in clouds.

MATERIAL HANDLING MACHINES AND SYSTEMS – UMI-TWINN PROJECT CONTRIBUTION

2019 ◽  
Vol 12 (1) ◽  
pp. 7-20
Author(s):  
Péter Telek ◽  
Béla Illés ◽  
Christian Landschützer ◽  
Fabian Schenk ◽  
Flavien Massi
Keyword(s):  
Material Handling ◽  
Digital Data ◽  
Flow Process ◽  
Research Directions ◽  
Scientific Excellence ◽  
Research Activities ◽  
New Research ◽  
Eu Project ◽  
The University

Nowadays, the Industry 4.0 concept affects every area of the industrial, economic, social and personal sectors. The most significant changings are the automation and the digitalization. This is also true for the material handling processes, where the handling systems use more and more automated machines; planning, operation and optimization of different logistic processes are based on many digital data collected from the material flow process. However, new methods and devices require new solutions which define new research directions. In this paper we describe the state of the art of the material handling researches and draw the role of the UMi-TWINN partner institutes in these fields. As a result of this H2020 EU project, scientific excellence of the University of Miskolc can be increased and new research activities will be started.

Tertiary English-majored Students’ Perceptions toward the Role of Pronunciation in English Language Learning and their Practicing Strategies

2020 ◽  
Vol 6 (2) ◽  
pp. 264-279
Keyword(s):  
Language Learning ◽  
English Language ◽  
Vital Role ◽  
English Language Learning ◽  
Structured Interviews ◽  
Efl Learners ◽  
The University

Accurate pronunciation has a vital role in English language learning as it can help learners to avoid misunderstanding in communication. However, EFL learners in many contexts, especially at the University of Phan Thiet, still encounter many difficulties in pronouncing English correctly. Therefore, this study endeavors to explore English-majored students’ perceptions towards the role of pronunciation in English language learning and examine their pronunciation practicing strategies (PPS). It involved 155 English-majored students at the University of Phan Thiet who answered closed-ended questionnaires and 18 English-majored students who participated in semi-structured interviews. The findings revealed that students strongly believed in the important role of pronunciation in English language learning; however, they sometimes employed PPS for their pronunciation improvement. Furthermore, the results showed that participants tended to use naturalistic practicing strategies and formal practicing strategies with sounds, but they overlooked strategies such as asking for help and cooperating with peers. Such findings could contribute further to the understanding of how students perceive the role of pronunciation and their PPS use in the research’s context and other similar ones. Received 10th June 2019; Revised 12th March 2020; Accepted 12th April 2020

Authority of Law: An Analysis of The Role of Police

2017 ◽  
Vol 2 ◽  
Author(s):  
Veronika Keir
Keyword(s):  
Policy Development ◽  
Crime Control ◽  
Legal Theory ◽  
Research Policy ◽  
Further Education ◽  
Full Time ◽  
Legal Research ◽  
Legal Studies ◽  
The University

<div class="page" title="Page 3"><div class="layoutArea"><div class="column"><p><span>Veronika is a recent graduate from the Honours Legal Studies program at the University of Waterloo. Her passions are socio-legal research, policy development, feminist legal theory, and crime control development. Veronika is currently working a full-time job at Oracle Canada, planning on pursuing further education in a Masters program. </span></p></div></div></div>

Chaplaincies in a “Post-Secular” Multicultural University

2015 ◽  
Vol 9 (2) ◽  
pp. 147-165 ◽  
Author(s):  
Adam Possamai ◽  
Arathi Sriprakash ◽  
Ellen Brackenreg ◽  
John McGuire
Keyword(s):  
Public Institutions ◽  
Religion And Spirituality ◽  
Scaling Down ◽  
The University

As universities in Australia are faced with a growth in diversity and intensity of religion and spirituality on campus, this article explores the work of chaplains and its reception by students on a multi-campus suburban university. It finds that the religious work of these professionals is not the primary emphasis in the university context; what is of greater significance to students and the university institution is the broader pastoral and welfare-support role of chaplains. We discuss these findings in relation to post-secularism theory and the scaling down of state-provided welfare in public institutions such as universities.

Land Crisis in Zimbabwe

2005 ◽  
Vol 1 (1) ◽  
pp. 35-48
Author(s):  
James Cox
Keyword(s):  
Traditional Religion ◽  
University Development ◽  
Land Redistribution ◽  
Small Grant ◽  
Religious Dimensions ◽  
Spirit World ◽  
Commercial Farms ◽  
The University ◽  
University Of Zimbabwe

Earlier this year, I received a small grant from the Edinburgh University Development Trust Fund to determine the feasibility of formulating a major research project exploring the religious dimensions within the recent land resettlement programme in Zimbabwe. Since spirit mediums had played such an important role in the first Shona uprising in 1896–97 against colonial occu¬pation (the so-called First Chimurenga) (Parsons, 1985: 50-51) and again in the war of liberation between 1972 and 1979 (the Second Chimurenga) (Lan, 1985), I suspected that these central points of contact between the spirit world and the living communities would be affecting the sometimes militant invasions of white commercial farms that began sporadically in 1998, but became systematic after the constitutional referendum of February 2000. Under the terms of the grant, I went with my colleague, Tabona Shoko of the University of Zimbabwe, in July and August 2004, to two regions of Zimbabwe: Mount Darwin in the northeast, where recent activities by war veterans and spirit mediums had been reported, and to the Mberengwa District, where land resettlement programmes have been widespread. This article reports on my preliminary findings in Mount Darwin, where I sought to determine if evidence could be found to link the role of Traditional Religion, particularly through spirit mediums, to the current land redistribution programme, and, if so, whether increasing levels of political intolerance within Zimbabwean society could be blamed, in part at least, on these customary beliefs and practices

The Role of The Students Association in The Promotion of Students' Speech Skills at The Khalid Bin Al Walid Institute at University of Muhammadiyah Mataram (ar)

2019 ◽  
Vol 7 (2) ◽  
pp. 59-72
Author(s):  
Erwin Erwin ◽  
Nasarudin Nasarudin ◽  
Husnan Husnan
Keyword(s):  
Student Organizations ◽  
Language Game ◽  
Qualitative Approach ◽  
The Media ◽  
Role Based ◽  
The University ◽  
Good Deeds ◽  
Speaking Skills

The purpose of this research is to explain the importance of the student organizations and describe their efforts to improve the speaking skills of students at the Mahad Khalid Bin Al Waleed at the University of Muhammadiyah Mataram. This research uses the qualitative approach with the descriptive type. The result shows the student organizations play an important role based on their objectives and functions. The objectives are to help the foundation and all parties in the Ma'had develop the students’ potential and qualification, and to be the place for the students to share their problems and complaints, while the functions are as one of the media to develop students’ quality, both the members of the non-member, and as the good examples and pioneers of any good deeds. The efforts done by student organizations in improving speaking skills are such as by making activities that lead to improving students' speaking skills like sticking vocabularies in each class and Friday activities such as language game, Arabic debate and short lecture.

Brothers in Arms: The Role of Broederbond Rectors in the Exercise of Hegemony at the University of Fort Hare, 1960–1981

Politeia ◽  
2018 ◽  
Vol 37 (1) ◽  
Author(s):  
Pamela Johnson
Keyword(s):  
Black Students ◽  
The State ◽  
University Administration ◽  
Independent States ◽  
University Of Fort Hare ◽  
The University

As members of the secret Afrikaner organisation, the Broederbond, two of the apartheid-era rectors at the University of Fort Hare were responsible for leading an institution that was supposed to spearhead the modernisation of ethnically defined homelands and their transition to independent states, whilst disseminating apartheid values among the black students. Based on unsorted and unarchived documents located in the personal files of the apartheid-era rectors, which included secret correspondence and memoranda of clandestine meetings, this paper illustrates the attempted exercise of hegemony by the apartheid state through its linked network with the university administration during the period 1960 to 1990. This is achieved by demonstrating the interaction between the state, Broederbond rectors and the black students at Fort Hare, who were subjected to persuasion and coercion as dictated by the state’s apartheid vision of a racially defined and separated society.

ROLE OF LIBRARIANS IN TEACHING INFORMATION LITERACY IN ZIMBABWEAN AND SOUTH AFRICAN UNIVERSITIES: A COMPARATIVE STUDY

Mousaion ◽  
2016 ◽  
Vol 33 (1) ◽  
pp. 23-42 ◽  
Author(s):  
Tinashe Mugwisi
Keyword(s):  
South Africa ◽  
South African ◽  
Information Literacy ◽  
Ethical Issues ◽  
University Libraries ◽  
Information And Communications Technologies ◽  
Communications Technologies ◽  
Information Skills ◽  
The University

Information and communications technologies (ICTs) and the Internet have to a large extent influenced the way information is made available, published and accessed. More information is being produced too frequently and information users now require certain skills to sift through this multitude in order to identify what is appropriate for their purposes. Computer and information skills have become a necessity for all academic programmes. As libraries subscribe to databases and other peer-reviewed content (print and electronic), it is important that users are also made aware of such sources and their importance. The purpose of this study was to examine the teaching of information literacy (IL) in universities in Zimbabwe and South Africa, and the role played by librarians in creating information literate graduates. This was done by examining whether such IL programmes were prioritised, their content and how frequently they were reviewed. An electronic questionnaire was distributed to 12 university libraries in Zimbabwe and 21 in South Africa. A total of 25 questionnaires were returned. The findings revealed that IL was being taught in universities library and non-library staff, was compulsory and contributed to the term mark in some institutions. The study also revealed that 44 per cent of the total respondents indicated that the libraries were collaborating with departments and faculty in implementing IL programmes in universities. The study recommends that IL should be an integral part of the university programmes in order to promote the use of databases and to guide students on ethical issues of information use.

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