Fluid mechanics Applications of fluid mechanics in climate modelling TERM PROJECT Submitted to Mustafa Ipekcioglu Of Eastern Mediterranean University By Gabani Ammar Mohamed Ahmed 22702441 In partial fulfillment of the requirements for the course ENGL201 Technical Report Writing In Foreign Languages Unit Famagusta, Turkish Republic of Northern Cyprus Date: 6/09/2023 Mechanical Engineering Eastern Mediterranean University Fluid mechanics ABSTRACT This report is on the applications of fluid mechanics in climate modelling. Fluid mechanics is a course engineers and physicists study and suffer a lot while studying. Thus, the report is written to convey that fluid mechanics is important for the well-being of humans and the environmental sustainability of the earth. Firstly, short-term uses of fluid mechanics are evinced to be true by explaining how weather forecasts and climate modelling depend on fluid mechanics. Also, the long-term benefits of fluid mechanics are shown to be true by elaborating how green energy and pollution tracking are only viable using fluid mechanics. The report concludes that fluid mechanics helps humans find safe habitats and have a more sustainable earth. i Mechanical Engineering Eastern Mediterranean University Fluid mechanics TABLE OF CONTENTS TABLE OF CONTENTS ------------------------------------------------------------------- ii LIST OF FIGURES ------------------------------------------------------------------- iii LIST OF SYMBOLS AND/OR ABBREVIATIONS ------------------------------- iv ------------------------------------------------------------------- 1 1. DAY-TO-DAY APPLICATIONS OF FLUID MECHANICS ---------------------- 2 INTRODUTION 1.1 WEATHER FORECAST -------------------------------------------------------- 2 1.2 CLIMATE MODELLING ------------------------------------------------------- 5 2. FLUID MECHANICS FOR THE ENVIRONMENTAL HEALTH ------------- 7 2.1 POLLUTION TRACKING 2.2 GREEN ENERGY -------------------------------------------------- ----------------------------------------------------------- 7 10 CONCLUSION ------------------------------------------------------------------- 12 REFERENCES ------------------------------------------------------------------- 13 ii Mechanical Engineering Eastern Mediterranean University Fluid mechanics LIST OF FIGURES Figure 1 Calculated rainfall mirrored against observed rainfall ---------- 4 Figure 2 Concentrations of pollution ---------------------------------------- 8 Figure 3 concentrations of pollution after reverse modelling ------------ 9 Figure 4 Wind speed at several altitudes ----------------------------------- 11 iii Mechanical Engineering Eastern Mediterranean University Fluid mechanics LIST OF SYMBOLS AND/OR ABBREVIATIONS CFD ------------------------------------------------------------- Computational fluid dynamics GCM ------------------------------------------------------------- General circulation model iv Mechanical Engineering Eastern Mediterranean University Fluid mechanics INTRODUCTION In the community of Physics and Engineering undergraduates and even postgraduates, we are often running into students who keep complaining about fluid mechanics. Fluid mechanics is a subfield of physics that studies the motion and forces that affect fluids, which include liquids and gases. It is a vast, multidisciplinary area that affects virtually every facet of daily life and is essential to much of science and engineering. To the unawareness of most of us, we are not able to see that this branch of physics is the primary basis for weather prediction and climate modelling. It was not until 1922 that an attempt to predict the weather using calculations of fluid mechanics principles was made. Lewis Fry Richardson published his work on weather prediction through calculations. Nonetheless, it took him a further 3 months to predict the weather for the coming 24 hours. The topic of this report is the applications of fluid mechanics in climate modelling. The main aim of this report is to convey the importance of Fluid mechanics in our day-to-day life as well as its importance to our environmental health. I chose to talk about this topic because I think many intelligent students pass this course with good grades but never work in the field of fluid mechanics later. This report is intended mainly for Physics, Mechanical and Civil engineering students. As they study this course and regardless of what grades they get they all suffer and thus question its usefulness. Not only current students but also fresh graduates might reconsider not taking a path that involves a fluid mechanics course they worked hard to understand. To succeed in my aforementioned mission, for the first constituent of this report as the dayto-day importance; I will be talking about the use of fluid mechanics in the weather forecast. As well as its use in climate modelling. To expand on this, for the second constituent; I will shift over 1 Mechanical Engineering Eastern Mediterranean University Fluid mechanics to the environmental cruciality of fluid mechanics as said earlier. And that is by stating its utilisation in pollution tracking and green energy. 1. DAY-TO-DAY APPLICATIONS OF FLUID MECHANICS. 1.1. WEATHER FORECAST The atmosphere behaves as a complex fluid system bringing about unpredictable motions known as weather. The intricate interplay of multiple physical processes interacting at different locations constitutes the basis of this complexity. For instance, a change in temperature would cause a change in pressure, propelling winds. In turn, winds transport water vapour. The vapour condensation and the following heat release would further enhance the temperature discrepancy. And so on these non-linear alterations go, exerting influence on our everyday existence by altering our mobility, shaping agricultural possibilities, determining our housing choices and even affecting our emotions. Despite the intricate nature of these occurrences, significant insights into atmospheric dynamics have been made. Thanks to fluid mechanics. To avoid all of this fluid mechanics comes into place. J.R. HOLTON (2015) argues that “Dynamic meteorology is the branch of fluid dynamics concerned with the meteorologically 2 Mechanical Engineering Eastern Mediterranean University Fluid mechanics significant motions of the atmosphere. It forms the primary scientific basis for weather and climate prediction, and thus plays a primary role in the atmospheric sciences.” (page 265). Explaining the cruciality of fluid mechanics can be portrayed by the governing mathematical model of fluid mechanics and has been proven to be easily applicable with the insurgence of computers. With the advancement in numerical weather prediction in recent years as well as an increase in computing power, it is now possible to generate high-resolution rainfall forecasts at the catchment scale and therefore more flood-casting systems are opting to use quantitative precipitation prediction from high resolution in order to extend the forecast lead time. This is particularly true in the flash flooding area where the model performance is dependent on the quick availability of knowledge of rainfall distribution in advance. 3 Mechanical Engineering Eastern Mediterranean University Fluid mechanics Figure 1: calculated rainfall mirrored against observed rainfall. Note: Adapted from Y. Xuan1, I. D. Cluckie2, and Y. Wang3. 2009. 1 Dept. of Hydro informatics and Knowledge Management, UNESCO-IHE Institute for Water Education, 2611 AX, Delft, The Netherlands. 2 Water and Environmental Management Research Centre (WEMRC), Dept. of Civil Engineering, University of Bristol, Bristol, BS8 1UP, UK. 3 Taiwan Typhoon and Flood Research Institute, Taichung 40763, Taiwan. (page 297). The line graph in Figure 1 shows rainfall flooding amounts that were calculated and plotted against amounts that were actual and observed. Although the 2 graphs do not exactly map into each other, it is quite evident that they follow the same trend. Which is quite useful when predicting such catastrophes. 4 Mechanical Engineering Eastern Mediterranean University Fluid mechanics 1.2 CLIMATE MODELLING Through offering the basic concepts for understanding the manners of fluids in the earth's atmosphere and seas, fluid mechanics plays a vital role in climate modelling. Able to reproduce, forecast and predict long-term climate patterns and alterations, we find that climate modelling is a subtle simulation. Through the achievement of this, we find many daily habits are bound to be changed. Like, the use of carbon-emitting cars, cruise ship companies may change their route and choice of what we eat. Are all examples of stuff we can change upon finding the earth's climate future to expect a better climate. The climate and its changes that we experience through time are impacted by and being influenced by the ocean condition as it changes over time. One of the most fascinating and difficult scientific topics is figuring out how the ocean interacts with the other components of the climate system, such as the atmosphere, cryosphere, and biosphere. These changes are so significant that MIT researchers and their collaborators at WHOI and other institutions use every tool at their disposal to study the system, including satellite and at-sea observations, theory, statistics, and models ranging from the analytical to some of the largest and most complex computer models ever created. Further mentioning the relation between oceanic circulations and fluid mechanics. The principles of mechanics and thermodynamics regulate the stratified fluid that makes up the ocean, which is propelled from its top surface by patterns of momentum and buoyancy fluxes. There are many different phenomena that occur in the water on a range of time and space scales, including tides, internal gravity waves, large-scale ocean currents, and geostrophic turbulence. The ocean 5 Mechanical Engineering Eastern Mediterranean University Fluid mechanics presents a difficult modelling problem since it is a turbulent fluid with energetically active scales that range from the global down to order 1 to 10 km horizontally and several tens of meters vertically. Over the course of the spectrum, significant scale interactions happen. The ocean also interacts with the cryosphere, which consists of land and sea ice, and it is home to life that is essential to biogeochemical cycles. MATTEW E. PETERS (2005) claims, during the last one hundred years, improvements in subgrid-scale parameterizations and computing power have taken us to have a greater capacity to simulate the climate system. General circulation models (GCMs) bear the ability to produce sensible climates and have become an invaluable utility for studying cloud-radiative feedback. (page 4216) RICHARD T. WETHERALD (2003) states that, simply, a GCM is a mathematical model composed of a system of partial differential equations derived from the basic laws of physics and fluid motion considering air as a fluid. (page 107) Observing the last two arguments, by MATTEW E. PETERS and RICHARD T. WETHERALD we can deduce that fluid mechanics is essential for climate modelling. 6 Mechanical Engineering Eastern Mediterranean University Fluid mechanics 2. IMPORTANCE OF FLUID MECHANICS FOR THE ENVIRONMENTAL HEALTH 2.1. POLLUTION TRACKING Pollution tracking is the process of measuring and monitoring the amount of different pollutants in the air. Air pollutants have a consequential effect on human health and the environment. Once again, fluid mechanics is how pollution tracking and environmental monitoring work. Understanding how the contaminants are spread out across the atmosphere and different fluid mediums including air and water is important for engineers and scientists. More so, we can have a habitable and sustainable environment. One method of pollution tracking is pattern identification using Computational fluid dynamics. Benjamin Ishii (2019) claims that, Computational fluid dynamics (CFD) allows the transient behavior of pollution dispersion to be modelled in a 3-dimensional space. These types of models offer researchers a practical way to simulate multiple pollutants and model pollutant concentrations in a city or a portion of a city. CFD offers the possibility of predicting changes in pollutant concentrations due to proposed changes to a city landscape before any construction takes place. This capability may allow city planners to simulate multiple layouts and ultimately improve the dispersion of pollutants in the city or area. (page 3) Knowing that Computational fluid dynamics is a computational method where complex yet crucial fluid mechanics laws are automated in order to be solved by computers in large 7 Mechanical Engineering Eastern Mediterranean University Fluid mechanics quantities and frequencies. We can yet again see that fluid mechanics is used and this time for pollution. One of the applications of Computational fluid dynamics was to model and predict the path of pollutants. Another application of application of Computational fluid dynamics is pollution source identification using a method called the direct inverse modelling. Mahmoud Bady (2013) claims that, while Computational fluid dynamics is normally used for studying the relationship between events and their cause to be able to predict similar events. Inverse modelling is for exploring adjacent characteristics such as source location. (page 2) Figure 2: shows the concentrations of pollution at 1s and 200s Note: adapted from Mahmoud Bady 2013, Fundamentals of Direct Inverse CFD Modeling to Detect Air Pollution Sources in Urban Areas Department of Environmental Engineering, Egypt-Japan University of Science and Technology (E-JUST), New Borg El-Arab City, Alexandria, Egypt. 8 Mechanical Engineering Eastern Mediterranean University Fluid mechanics Figure 3: shows the concentrations of pollution after reverse modelling Note: adapted from Mahmoud Bady 2013, Fundamentals of Direct Inverse CFD Modeling to Detect Air Pollution Sources in Urban Areas Department of Environmental Engineering, Egypt-Japan University of Science and Technology (E-JUST), New Borg El-Arab City, Alexandria, Egypt. Figures 2 shows the location of the source which is the white rectangle and the dispersion of the pollutants after 1s and 200s as shown. Figure 3 on the other hand, shows concentration of pollutants after the inverse modelling has been applied to the dispersed pollution in figure 2. Figure 3 is what the inverse modelling tells us about the source of the pollution by giving us the concentration in terms of accumulation over time. Previously, knowing where the source is - the white rectangle – inverse modelling seems to give a good idea about the location of the source. 9 Mechanical Engineering Eastern Mediterranean University Fluid mechanics 2.2. GREEN ENERGY Green energy is an emission-less type of energy generation. As they release greenhouse gases such as carbon dioxide. The demand for this type of energy has increased highly during the years as humans more and more discover the contaminated atmosphere has inflated the earth's temperature to unbearable limits. This would most likely cause ice glaciers in the poles to melt, not only flooding entire countries but releasing infectious bacteria that is now frozen in those glaciers in bodies of extinct animals. Bacteria that experts deemed uncontrollable as humans living now have no developed necessary immunity to combat them. A way of overcoming the harmful emissions is the use of green energy. In order to have green energy resources we must utilize the naturally available energy and transform them to the desired state in accordance to need. Most of the green energy is found in Wind turbines, hydraulic turbines and ocean wave converters. As you can see, all of these are dependent on moving fluids. A fluid in motion is used to move energy generators. For this to happen in the most time and cost-efficient way, fluid mechanics is needed. The use of computational fluid dynamics is important for knowing about how much each wind turbine is expected to give to us as opposed to setting up a whole wind turbine just to test it. Nak Joon Choi (2014) claims that To study the aerodynamic power output of wind turbines according to the inter-turbine spacing, an experimental method is unrealistic because of the high cost required and length of time involved. The computational fluid dynamics approach can be 10 Mechanical Engineering Eastern Mediterranean University Fluid mechanics successfully applied with minimum cost and time compared to the experimental method. (page 7484). Figure 4: Wind speed at several altitudes Note: adapted from; CFD Study on Aerodynamic Power Output Changes with Inter-Turbine Spacing Variation for a 6 MW Offshore Wind Farm Nak Joon Choi 1 , Sang Hyun Nam 2 , Jong Hyun Jeong 2 and Kyung Chun Kim 1, 1 School of Mechanical Engineering, Pusan National University, San 30, Jangjeon-dong, Geumjeong-Gu, Busan 2 DNDE Inc., Busan 11 Mechanical Engineering Eastern Mediterranean University Fluid mechanics This graph shows the speed of winds at different altitudes from different locations calculated using the fluid mechanics principles. Colours indicate the distances of the location of interest from a predefined reference position. CONCLUSION In this report, I took my chance and tried to explain why I think fluid mechanics, as a scope of study, has true applications that are beneficial to humans. To achieve this, I have divided the discourse into two separate complementary sections. With one being the day-to-day uses of fluid mechanics and where humans encounter it on a daily basis. The other is the long-term effects of utilizing fluid mechanics as a humanity on earth. Upon the expansion on these two sections giving examples of crucial uses that depend heavily on fluid mechanics; we can deduce that fluid mechanics Helps humans choose wisely where to best live safe from extreme weather conditions, and ensures a more sustainable earth. 12 Mechanical Engineering Eastern Mediterranean University Fluid mechanics REFERENCES Bady, M. (2013) Fundamentals of direct inverse CFD modelling to detect air pollution sources in urban areas, SCIRP Open Access. Available at: https://www.scirp.org/html/1-2570004_30593.htm (Accessed: 27 August 2023). Choi, N.J. (2014) CFD study on aerodynamic power output changes with Inter-Turbine Spacing Variation for a 6 MW Offshore Wind Farm, schematic acholar. Available at: https://www.semanticscholar.org/paper/CFD-Study-on-Aerodynamic-Power-OutputChanges-with-Choi-Nam/c3fdd5207b498735bd048e211cd74f86078ce741 (Accessed: 06 September 2023). ISHII, B. (2019a) Modeling pollutant dispersion in urban areas with computational fluid dynamics, KREX.K-STATE.EDU. Available at: 13 Mechanical Engineering Eastern Mediterranean University Fluid mechanics https://krex.k-state.edu/bitstream/handle/2097/39602/BenjaminIshii2019.pdf?sequence=1 (Accessed: 27 August 2023). J. HOLTON (2015) Estimating the circulation and climate of the Ocean, MIT PAOC. Available at: http://paocweb.mit.edu/research-group/estimating-the-circulation-and-climate-of-theocean (Accessed: 16 August 2023). Peters, M.E. and Bretherton, C.S. (2005) A simplified model of the Walker circulation with an interactive ocean mixed layer and cloud-radiative feedbacks, AMETSOC. Available at: https://journals.ametsoc.org/view/journals/clim/18/20/jcli3534.1.xml (Accessed: 16 August 2023). WETHERALD, R.T. (2002) ‘General Circulation Model Description and Experimental Procedure’, in Encyclopedia of Physical Science and Technology. San Diego: Academic Press. Available at: https://www.sciencedirect.com/topics/mathematics/general-circulation-models (Accessed: 16 August 2023) Xuan, Y. (2009) Uncertainty analysis of hydrological ensemble forecasts in a ..., Schematic scholar. 14 Mechanical Engineering Eastern Mediterranean University Fluid mechanics Available at: https://www.semanticscholar.org/paper/Uncertainty-analysis-of-hydrological-ensemblein-a-Xuan-Cluckie/54393bead0255315bff55094b77b5de2c66189aa (Accessed: 27 August 2023). 15 Mechanical Engineering Eastern Mediterranean University
