Study of heat and mass transfer applications in the field of engineering by using OpenFOAM

The aim of the project is to study OpenFOAM software and establish a well-based guide of standard and complex heat and mass transfer applications in engineering. OpenFOAM is a free, open source CFD software package. By being open, OpenFOAM offers users complete freedom to customise and extend its existing functionality. On the other hand, OpenFOAM offers a quick start user guide and there also is little available documentation and several examples. Thus, the project intends to: - Prepare an introductory and complete user guide to OpenFOAM with solved standard heat and mass transfer applications to the beginners, specially bachelor students ‐ Numerical simulation of complex heat and mass transfer applications in engineering with OpenFOAM in two‐ and three‐dimensional problems ‐ Practice in developing engineering projects by combining technical work with economic and environmental aspectsThe main tasks to be carried out in this project will be to: - Edit problems solved with OpenFOAM including explanations and detailed considerations in order to prepare a guide for new learners, specially bachelor students - Work in the study and analysis of heat and mass transfer simulations involving real engineering problems - Determine feasibility of the engineering project to be carried out - Study the socio-economics aspects in fluid dynamics applications solved by numerical simulation and fields of interest - Results analysi

Influence of convex and concave curvatures in a coastal dike line on wave run-up

Due to climatic change and the increased usage of coastal areas, there is an increasing risk of dike failures along the coasts worldwide. Wave run-up plays a key role in the planning and design of a coastal structure. Coastal engineers use empirical equations for the determination of wave run-up. These formulae generally include the influence of various hydraulic, geometrical and structural parameters, but neglect the effect of the curvature of coastal dikes on wave run-up and overtopping. The scope of this research is to find the effects of the dike curvature on wave run-up for regular wave attack by employing numerical model studies for various dike-opening angles and comparing it with physical model test results. A numerical simulation is carried out using DualSPHysics, a mesh-less model and OpenFOAM, a mesh-based model. A new influence factor is introduced to determine the influence of curvature along a dike line. For convexly curved dikes (ad = 210° to 270°) under perpendicular wave attack, a higher wave run-up was observed for larger opening angles at the center of curvature whereas for concavely curved dikes (ad = 90° to 150°) under perpendicular wave attack, wave run-up increases at the center of curvature as the opening angle decreases. This research aims to contribute a more precise analysis and understanding the influence of the curvature in a dike line and thus ensuring a higher level of protection in the future development of coastal structures.Peer ReviewedPostprint (published version

Study of the Wall Thermal Condition Effect in a Lean-Premixed Downscaled Can Combustor Using Large-Eddy Simulation

The primary purpose of this study is to evaluate the ability of LES, with a turbulent combustion model based on steady flamelets, to predict the flame stabilization mechanisms in an industrial can combustor at full load conditions. The test case corresponds to the downscaled Siemens can combustor tested in the high pressure rig at the DLR. The effects of the wall temperature on the prediction capabilities of the codes is investigated by imposing several heat transfer conditions at the pilot and chamber walls. The codes used for this work are Alya and OpenFOAM, which are well established CFD codes in the fluid mechanics community. Prior to the simulation, results for 1-D laminar flames at the operating conditions of the combustor are compared with the detailed solutions. Subsequently, results from both codes at the mid-plane are compared against the experimental data available. Acceptable results are obtained for the axial velocity, while discrepancies are more evident for the mixture fraction and the temperature, particularly with Alya. However, both codes showed that the heat losses influence the size and length of the pilot and main flame.The research leading to these results has received funding through the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7, 2007-2013) under the grant agreement No. FP7-290042 for the project COPA-GT and the European Union’s Horizon 2020 Programme (2014-2020) and from Brazilian Ministry of Science, Technology and Innovation through Rede Nacional de Pesquisa (RNP) under the HPC4E Project, grant agreement No. 689772. The authors thankfully acknowledge the computer resources, technical expertise and assistance provided by the Red Española de Supercomputación (RES).Peer ReviewedPostprint (author's final draft

Comparison of computational codes for direct numerical simulations of turbulent Rayleigh-B\'enard convection

Computational codes for direct numerical simulations of Rayleigh-B\'enard (RB) convection are compared in terms of computational cost and quality of the solution. As a benchmark case, RB convection at $Ra=10^8$ and $Pr=1$ in a periodic domain, in cubic and cylindrical containers is considered. A dedicated second-order finite-difference code (AFID/RBflow) and a specialized fourth-order finite-volume code (Goldfish) are compared with a general purpose finite-volume approach (OpenFOAM) and a general purpose spectral-element code (Nek5000). Reassuringly, all codes provide predictions of the average heat transfer that converge to the same values. The computational costs, however, are found to differ considerably. The specialized codes AFID/RBflow and Goldfish are found to excel in efficiency, outperforming the general purpose flow solvers Nek5000 and OpenFOAM by an order of magnitude with an error on the Nusselt number $Nu$ below $5\%$. However, we find that $Nu$ alone is not sufficient to assess the quality of the numerical results: in fact, instantaneous snapshots of the temperature field from a near wall region obtained for deliberately under-resolved simulations using Nek5000 clearly indicate inadequate flow resolution even when $Nu$ is converged. Overall, dedicated special purpose codes for RB convection are found to be more efficient than general purpose codes.Comment: 12 pages, 5 figure

Performance of interFoam on the simulation of progressive waves

The performance of interFoam (a widely-used solver within the popular open source CFD package OpenFOAM) in simulating the propagation of a nonlinear (stream function solution) regular wave is investigated in this work, with the aim of systematically documenting its accuracy. It is demonstrated that over time there is a tendency for surface elevations to increase, wiggles to appear in the free surface, and crest velocities to become (severely) overestimated. It is shown that increasing the temporal and spatial resolution can mitigate these undesirable effects, but that a relatively small Courant number is required. It is further demonstrated that the choice of discretization schemes and solver settings (often treated as a "black box" by users) can have a major impact on the results. This impact is documented, and it is shown that obtaining a "diffusive balance" is crucial to accurately propagate a surface wave over long distances without requiring exceedingly high temporal and spatial resolutions. Finally, the new code isoAdvector is compared to interFoam, which is demonstrated to produce comparably accurate results, while maintaining a sharper surface. It is hoped that the systematic documentation of the performance of the interFoam solver will enable its more accurate and optimal use, as well as increase awareness of potential shortcomings, by CFD researchers interested in the general CFD simulation of free surface waves.Comment: 18 pages and 23 figure

Feasibility study for estimating the offshore shear layer from on shore measurements

This paper presents an open source computational fluid dynamics (CFD) study of air flow over a complex terrain. The open source C++ toolbox OpenFOAM has been used for the CFD analysis and the terrain considered is a scale model of Berlengas Island, which lies close to the Portuguese coast. In order to validate the CFD model, experimental work has been carried out in an open-section wind tunnel using hot-wire anemometry to measure the wind profiles above the island. In the majority of cases, the OpenFOAM CFD solutions show very good agreement with the experimental wind profile data, confirming that open source CFD solutions are possible for environmental flows over complex terrain. Such an analysis demonstrates the feasibility of estimating offshore boundary layer effects from onshore measurements

Towards safer mining: the role of modelling software to find missing persons after a mine collapse

Purpose. The purpose of the study is to apply science and technology to determine the most likely location of a container in which three miners were trapped after the Lily mine disaster. Following the collapse of the Crown Pillar at Lily Mine in South Africa on the 5th of February 2016, there was a national outcry to find the three miners who were trapped in a surface container lamp room that disappeared in the sinkhole that formed during the surface col-lapse. Methods. At a visit to Lily Mine on the 9th of March, the Witwatersrand Mining Institute suggested a two-way strategy going forward to find the container in which the miners are trapped and buried. The first approach, which is the subject of this paper, is to test temporal 3D modeling software technology to locate the container, and second, to use scientific measurement and testing technologies. The overall methodology used was to first, request academia and research entities within the University to supply the WMI with ideas, which ideas list was compiled as responses came in. These were scrutinized and literature gathered for a conceptual study on which these ideas are likely to work. The software screening and preliminary testing of such software are discussed in this article. Findings. The findings are that software modeling is likely to locate the present position of the container, but accurate data and a combination of different advanced software packages will be required, but at tremendous cost. Originality. This paper presents original work on how software technology can be used to locate missing miners. Practical implications. The two approaches were not likely to recover the miners alive because of the considerable time interval, but will alert the rescue team and mine workers when they come in close proximity to them.Мета. Визначення можливого місця локалізації лампового приміщення контейнера, в якому опинилися три шахтаря після аварії на шахті Лілі (Барбертон, Мпумаланга) методом комп’ютерного моделювання. Після обвалення стельового цілика на шахті Лілі 5 лютого 2016 року почалася національна кампанія з порятунку трьох шахтарів, які залишилися у ламповому приміщенні поверхневого транспортного контейнера, що провалився в утворену після вибуху воронку. Методика. Співробітниками Гірничого Інституту (Уітуотерс) запропонована двостадійна стратегія пошуку контейнера, в якому існує ймовірність знаходження шахтарів. В рамках першого підходу (який розглядається у даній статті) для виявлення контейнера здійснювалось випробування комп’ютерної технології 3D-моделювання в часі. Другий підхід передбачав технологію проведення наукового вимірювання та експерименту. В цілому, методологія включала, насамперед, підключення викладацького та наукового складу університету до вирішення проблеми шляхом комплексної генерації ідей, які були об’єднані в загальний список, вивчені із залученням відповідних літературних джерел, і найбільш реалістичні ідеї були виділені із загального переліку. Дана стаття розглядає результати комп’ютерної експертизи цих ідей та перевірки надійності відповідного програмного забезпечення. Результати. Для зручності моделювання процес обвалення був розділений на три окремі фази: руйнування воронки, руйнування західного схилу та небезпека ковзання на південних схилах. Ідентифіковано програмні технології, які можуть імітувати рух контейнера у перших двох фазах обвалення. В результаті моделювання у програмному забезпеченні ParaView виявлено місце розташування даного контейнера. Виконано аналіз південного схилу за допомогою ArcGIS і складені карти небезпеки схилу для району, а також підземні карти порятунку з маршрутами евакуації. Встановлено, що комп’ютерне моделювання може визначити місцезнаходження контейнера, але для цього потрібні точні вихідні дані й комплекс дорогих високоефективних програмних пакетів. Наукова новизна. Вперше застосовано комплекс комп’ютерних технологій та програмного забезпечення для пошуку зниклих шахтарів після аварійних ситуацій у підземному просторі шахт. Практична значимість. При застосуванні двостадійної стратегії пошуку шахтарів, що опинилися під завалом порід, команда рятувальників отримає сигнал про наближення до їх місцезнаходження.Цель. Определение возможного места локализации лампового помещения контейнера, в котором оказались три шахтера после аварии на шахте Лили (Барбертон, Мпумаланга) методом компьютерного моделирования. После обрушения потолочного целика на шахте Лили 5 февраля 2016 года началась национальная кампания по спасению трех шахтеров, оставшихся в ламповом помещении поверхностного транспортного контейнера, который провалился в воронку, образовавшуюся после взрыва. Методика. Сотрудниками Горного Института (Уитуотерс) предложена двухстадийная стратегия поиска контейнера, в котором существует вероятность нахождения шахтеров. В рамках первого подхода (который рассматривается в данной статье) для обнаружения контейнера производилось испытание компьютерной технологии 3D-моделирования во времени. Второй подход предполагал технологию проведения научного измерения и эксперимента. В целом, методология включала, прежде всего, подключение преподавательского и научного состава университета к решению проблемы путем комплексной генерации идей, которые были объединены в общий список, изучены с привлечением соответствующих литературных источников, и наиболее реалистичные идеи были выделены из общего списка. Настоящая статья рассматривает результаты компьютерной экспертизы данных идей и проверки надежности соответствующего программного обеспечения. Результаты. Для удобства моделирования процесс обрушения был разделен на три отдельные фазы: разрушение воронки, разрушение западного склона и опасность скольжения на южных склонах. Идентифицированы программные технологии, которые могут имитировать движение контейнера в первых двух фазах обрушения. В результате моделирования в программном обеспечении ParaView выявлено местоположение данного контейнера. Выполнен анализа южного склона с помощью ArcGIS и составлены карты опасности склона для района, а также подземные карты спасения с маршрутами эвакуации. Установлено, что компьютерное моделирование может определить местонахождение контейнера, но для этого нужны точные исходные данные и комплекс дорогостоящих высокоэффективных программных пакетов. Научная новизна. Впервые применен комплекс компьютерных технологий и программного обеспечения для поиска пропавших шахтеров после аварийных ситуаций в подземном пространстве шахт. Практическая значимость. При применении двухстадийной стратегии поиска шахтеров, оказавшихся под завалом пород, команда горноспасателей получит сигнал о приближении к их местонахождению.The results of the article were obtained without the support of any of the projects or funding