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1	Skyfallsanalys i urban miljö : En komparativ studie mellan MIKE 21 och MIKE FLOOD / Flood modelling in urban areas : A comparative study of MIKE 21 and MIKE FLOOD Andersson, Elin January 2020 (has links) Redan idag har många kommuner i Sverige drabbats av skyfall och ett förändrande klimat indikerar att skyfall kommer bli vanligare. Översvämningar till följd av skyfall kan ge konsekvenser som skador på hus, vägar och även utgöra fara för människors hälsa. Skyfallskartering är ett verktyg som kan användas för att identifiera utsatta områden vid inträffandet av ett extremt regnförlopp. DHI har utvecklat MIKE 21 och MIKE Flood som kan användas vid skyfallsmodellering. MIKE Flood är en kopplad 1D-2D modell där ledningsnätet integreras. MIKE 21 är en 2D modell där regnets transportväg på ytan simuleras, ledningsnätet representeras av ett schablonvärde som dras bort från regnet som belastar modellen. Denna studie avser att jämföra dessa modeller för att undersöka behovet av att integrera ledningsnätet, samt utreda hur olika belastningar på ledningsnätet påverkar resultatet. Denna komparativa studie bygger på att MIKE 21 och MIKE Flood sätts upp för samma område lokaliserat i Nacka. Modelleringen resulterar i en karta som visar vattendjup och översvämningens utbredning. Resultatet visar att den största differensen mellan vattendjupen uppstår för djup mellan 0.1 till 0.3 meter. Vidare ger MIKE Flood generellt en större översvämningsutbredning än MIKE 21. Anledningen till denna skillnad är interaktionen mellan 1D och 2D modellen i MIKE Flood. Valet av schablonvärde är viktigt för MIKE 21 modellen då det har en stor påverkan på översvämningsutbredningen. Ledningsnätet betydelse minskar desto mer extrem nederbörden är. / Several municipalities in Sweden have been affected by cloudbursts and a changing climate indicates a future where these events gets more common. Cloudburst are events where extreme precipitation takes place under a short period of time. The consequences is flooding where damages to property and impede accessibility for emergency vehicles are some possible effects. Flood modelling is a way to identify vulnerable areas so that mitigations can be implemented. For example municipalities can use it when planning for new household areas and infrastructure. The Danish Hydrological Institute (DHI) has developed MIKE 21 and MIKE Flood. MIKE Flood is a coupled 1D-2D model while MIKE 21 is a 2D model. For the coupled model the storm water collection system can be integrated and represented by the model MIKE Urban. In the MIKE 21 model the collection system is represented by withdrawing a standard value from the applied rainfall. This comes with the assumption that the collection system fills up completely with the assumed capacity represented by the standard value. Since, MIKE Flood is a coupled 1D-2D model it requires more time and data to set up than the 2D model. Therefore, this study aims to compare these models in order to evaluate the impact of implementing the storm water collection system. Further, to evaluate how the division of the rain loads to each model affect the modelling results. This thesis is performed by setting up MIKE 21 and MIKE Flood for an area in Nacka. The models will be run for six scenarios, which results in a total of 12 simulations. For the scenarios two different recurrences are tested, a 100 and 50 year cloudburst event. Further, the collection system is represented with three different loads corresponding to a 5, 10 or 20 year rainfall event. The modelling results in maps containing water depths and flood extent. In order to compare the models the generated water depths and extent was compared. If the difference between the models was lower than 0.1 meter they was assumed to generate approximately the same result. In order to examine how well MIKE 21 and MIKE Flood matched in the different scenarios an index, measure of fit, was calculated. Moreover, the interaction between the 1D and 2D model was investigated for MIKE Flood. The result showed that there was a difference in flood depth and extent between MIKE 21 and MIKE Flood. Generally there were more flooded cells in MIKE Flood than in MIKE 21 for each scenario besides one. The larges difference between generated water depths was for depths between 0.1 to 0.3 meters. MIKE flood generates a bigger flood extent downstream along the collection system due to the lack of capacity in those parts of the collection system, along Vikdalsvägen the collection system seem to have the capacity to handle a 5 year load. The probable reason for the difference is the interaction between the collection system and 2D model. The collection system, MIKE Urban, enters new paths for the rain to travel that is not available in a 2D model. In areas where the capacity is reached there will be a flux from the 1D model to the 2D model and in areas whit capacity the flux can be in the opposite direction. The assumption that the collection system fills up entirely is not correct for Nacka. Further, the difference between the results from MIKE 21 and MIKE Flood increased with a higher network load. Which indicates that the importance of the storm water collection system reduces with more extreme precipitation events. That is the reason the index, measure of fit, is higher for the scenarios with a cloudburst of a 100 year return period. 1D-2D modell 2D modell dagvattenledningsnät skyfallskartering Engineering and Technology Teknik och teknologier
2	Höjddata i översvämningsmodellering : En fallstudie om hur höjdmodellens upplösning kan förbättra precisionen hos den 1D/2D-kopplade hydrauliska modellen LISFLOOD-FP / Elevation data in inundation modelling : A case study about how the resolution of the digital elevation model can increase the precision for the 1D-2D coupled hydraulic model LISFLOOD-FP Ekholm, Disa January 2022 (has links) Syftet med fallstudien var att undersöka möjligheterna och nyttan med att implementera en höjdmodell med högre upplösning i SMHI:s översvämningsmodellering som tillämpar den hydrauliska modellen LISFLOOD-FP. SMHI utfärdar översvämningsvarningar och det är därför av vikt att översvämningsmodelleringen håller hög kvalitet. Samtidigt kräver modelleringen tid och resurser från Nationellt Superdatorcentrum i Linköping, NSC. Därför vägdes de potentiella fördelarna med högre upplösning mot förlängd körtid. Fallstudien bestod av två delar där en höjdmodell på två meters upplösning i xy-planet implementerades och jämfördes med den i dagsläget uppställda modellen på fem meters upplösning. Detta gjordes genom att återskapa översvämningstillfällen med dess flöden från S-HYPE och mätningar. I studiens första del hämtades satellitdata från Copernicus från två tidigare översvämningstillfällen för validering av över-svämningsmodelleringen. De tidigare översvämningstillfällena var dels i Emån i Småland år 2012 och dels i Västerdalälven i Dalarna år 2018. Ett index för passning beräknades mellan översvämningskartorna producerade med två respektive fem meters upplösning gentemot satellitbilderna för att kvantifiera överlappande ytor. Därtill beräknades vattendragens lutning för att undersöka om det fanns indikationer på något samband med förändring i index med ökad upplösning på höjdmodellen. Studiens andra del bestod i att undersöka hur höjdmodellens upplösning påverkar vattnets spridning kring översvämningsvallar i modellen. I undersökningen återskapades ett översvämningstillfälle från 2020 i Helige å i Småland. Ett antal delavrinningsområden visade sig instabila för den högre upplösta höjdmodellen och kunde därför endast simuleras med lägre flöden. Erhållna resultat visade dock på att översvämningskarteringen förbättrades med upplösningen två meter vid jämförelse med data från Copernicus. Körtiden ökade dock med över 12 gånger vid simulering av högre upplösning. Vidare visades tröskeleffekter i studiens resultat, då översvämnings-vallen stoppade vattnet i den högre upplösta höjdmodellen men inte i den med lägre upplösning. På grund av stabilitetsproblemet och studiens begränsade omfattning, kunde slutsats inte dras om huruvida SMHI bör implementera en höjdmodell med två meters upplösning i systemet för översvämningsvarningar. Däremot kunde konstateras att stabiliteten i modellen måste öka för att det ska vara möjligt. Slutligen drogs slutsatsen att det förekommer tröskeleffekter mellan de två höjdmodellerna och att prestandan ökar generellt för den högre upplösningen när det kommer till precisionen i översvämningsmodelleringen. / The purpose of this case study was to examine the possibilities and advantages of implementing a DEM with higher resolution in inundation modelling at SMHI, the Swedish Meteorological and Hydrological Institute, which uses the hydraulic model LISFLOOD-FP. The institute issues flood warnings and therefore it is of high importance that the innundation modelling gives adequate results. On the other hand, running the models at a higher spatial resolution takes more time and resources. Therefore, potentially improved modelling results were discussed in a context of prolonged runtime. The case study consisted of two parts where a Digital Elevation Model, DEM of two meter resolution was implemented and compared to the five meter DEM that is currently in use. This was done by recreating previous flooding events by using discharge data from S-HYPE. In the first part, satellite data from Copernicus from two previous flooding events in Sweden were used for model validation in comparison with the results from inundation models of SMHI for the different DEM:s. An index was calculated to quantify the overlapping inundation areas. The events were at the river Emån in 2012 and at Västerdalälven in 2018. Moreover, the slope of the rivers within each study area was calculated to investigate correlation between improved flood modelling results for higher DEM resolution and slope of the rivers. The second part of the study investigated flood embankments for the two different DEM:s around Helige å river. A flooding event which took place in 2020 was recreated and the water flow around the built embankments was compared for the two resolutions. Running the models, it turned out that simulations of several subcatchment areas were unstable with the two meter DEM, and could only be run with lower flow. The obtained results, however, revealed an improved inundation modelling for the DEM with a resolution of 2 m for all study areas in comparison to the data from Copernicus; however the runtime was increased by over 12 times. Moreover, the results also showed threshold effects, where the flooding was impeded by the flooding embankment with the two meter DEM but not at the lower resolution. Due to the stability issue and the limited scope of this study, it cannot be concluded whether SMHI should implement the two meter DEM in their flood warnings system. However, it was concluded that the stability has to be increased to make it feasible. It was also concluded that there are threshold effects between the two DEM:s and that the performance seems to increase overall for the higher resolution when it comes to precision of the modelling. flood inundation modelling LISFLOOD-FP 1D-2D coupled model hydraulic modelling digital elevation model DEM resolution threshold effect översvämningsmodellering hydraulisk modellering LISFLOOD-FP kopplad 1D/2D-modell höjdmodell DEM upplösning tröskeleffekt
3	Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modelling McGee, Seán January 2015 (has links) Fuel cell systems are becoming more commonplace as a power generation method and are being researched, developed, and explored for commercial use, including portable fuel cells that appear in laptops, phones, and of course, chargers. This thesis examines a model constructed on inspiration from the myFC PowerTrekk, a portable fuel cell charger, using COMSOL Multiphysics, a finite element analysis software. As an educational tool and in the form of zero-dimensional, two-dimensional, and three-dimensional models, an investigation was completed into the geometric construction, air conditions and compositions, and product materials with a best case scenario completed that summarizes the results identified. On the basis of the results of this research, it can be concluded that polyoximetylen and high-density polyethylene were considered as possible materials for the majority of the product, though a more thorough investigation is needed. Air flow of above 10 m/s, air water vapour mass fraction below 50% and initial temperature between 308K and 298K was considered in this best scenario. Suggestions on future expansions to this project are also given in the conclusion. 0D model 2D model 3D model chemical engineering Comsol Multiphysics energy environment FC fluid dynamics fuel cell systems heat transfer JAQ laboratory experiments mobile charging modeling modelling myFC PEM polymer electrolyte membrane PowerTrekk process engineering proton exchange membrane sustainability 0D-Modell 2D-Modell 3D-Modell Chemieingenieurwesen COMSOL Multiphysics Energie Umwelt FC Fluiddynamik Brennstoffzellensysteme Wärmeübertragung JAQ Laborexperimente mobile Ladesysteme Modellieren myFC PEM Feststoffpolymer-Brennstoffzelle PowerTrekk Verfahrenstechnik Protonenaustauschmembran-Brennstoffzelle Nachhaltigkeit 0D-modell 2D-modell 3D-modell kemiteknik Comsol Multiphysics energi miljö FC fluiddynamik bränslecellssystem värmeöverföring JAQ laboratorieförsök mobil laddning modellering myFC PEM polymerelektrolytmembran PowerTrekk processteknik protonväxlingsmembran hållbarhet Chemical Engineering Kemiteknik

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Skyfallsanalys i urban miljö : En komparativ studie mellan MIKE 21 och MIKE FLOOD / Flood modelling in urban areas : A comparative study of MIKE 21 and MIKE FLOOD

Thermal energy management and chemical reaction investigation of micro-proton exchange membrane fuel cell and fuel cell system using finite element modelling