TOUGH2Viewer 2.0: A multiplatform tool for fully 3D Voronoi TOUGH grids

The software TOUGH2Viewer 2.0, originally available since 2012, is an enhanced visualization software specifically designed to visualize the results of TOUGH simulations performed using structured and fully unstructured 3D Voronoi grids. 3D Voronoi grids permit a great degree of flexibility when accurate numerical simulations are required. The TOUGH family of simulators represents a set of software well-known worldwide for numerical modeling and simulation for coupled transport of water, vapor, non-condensable gas and heat in porous and fractured media. Nevertheless, TOUGH has no native enhanced pre- and post-processing tools, and several pre- and post-processing tools have been developed. Using TOUGH2Viewer the users can interactively navigate the model, a 3-dimensional virtual environment, by means of a Graphical User Interface (GUI). This new version of TOUGH2viewer allows the editing of numerical models by dedicated GUIs, adding pre-processing capabilities

Efficient unstructured mesh generation for marine renewable energy applications

Renewable energy is the cornerstone of preventing dangerous climate change whilst maintaining a robust energy supply. Tidal energy will arguably play a critical role in the renewable energy portfolio as it is both predictable and reliable, and can be put in place across the globe. However, installation may impact the local and regional ecology via changes in tidal dynamics, sediment transport pathways or bathymetric changes. In order to mitigate these effects, tidal energy devices need to be modelled in order to predict hydrodynamic changes. Robust mesh generation is a fundamental component required for developing simulations with high accuracy. However, mesh generation for coastal domains can be an elaborate procedure. Here, we describe an approach combining mesh generators with Geographical Information Systems. We demonstrate robustness and efficiency by constructing a mesh with which to examine the potential environmental impact of a tidal turbine farm installation in the Orkney Islands. The mesh is then used with two well-validated ocean models, to compare their flow predictions with and without a turbine array. The results demonstrate that it is possible to create an easy-to-use tool to generate high-quality meshes for combined coastal engineering, here tidal turbines, and coastal ocean simulations

지열히트펌프시스템의 최적 설계를 통한 저온지열자원의 활용성 평가

학위논문 (박사)-- 서울대학교 대학원 : 지구환경과학부, 2015. 2. 이강근.Simulation models for evaluating utilization of low-enthalpy geothermal resources through the optimally designed geothermal heat pump (GHP) system is suggested. Firstly, a numerical model for the simulation of temperature changes in a borehole heat exchanger (BHE) with fluid circulating through U-tubes is developed. The model can calculate the thermal energy transferred from heat pumps to BHEs while considering the nonlinear relationship between temperature of the circulating fluid and the thermal energy. The use of the developed model enables also the design of a GHP system with the view of pursuing efficiency and financial benefit. The developed model is validated by comparing two measurement datasets with their respective simulation results. In addition, it is used to analyze the sensitivities of design parameters that can affect the performance of the closed-loop GHP system. The most sensitive parameters on the system are the thermal conductivity of the ground and the Darcian groundwater velocity considering acceptable distribution range in the realm of nature. Maximum change of the circulating fluid temperature at the BHE outlet is about 4℃ when thermal conductivity of the ground changes from 2 W/mK to 5 W/mK and the Darcian groundwater velocity changes from 10-8 m/s to 10-6 m/s, respectively. The numerical evaluation of a real GHP system with 28 BHEs and 79 heat pumps involves consideration of the base case and modified cases. In all cases, the temperatures of the circulating fluid at the BHE inlet and outlet, heat pump efficiency, and the heating power and electric power of heat pumps are obtained. The most cost-effective system in this case is for there to be 4, 6, and 6 BHEs on the first, second, and third floors, respectively. The next version of the numerical simulator and grid generator is developed to consider multiple BHEs simultaneously. Thus, massively parallel computing procedures into the simulator are introduced to improve distributing memory requirements and computational efficiency for solving large simulation problems with a great number of grid-blocks. The new grid generator is designed to produce a simulation domain with multiple BHEs. The newly developed simulation model can consider thermal interactions among BHEs when the system is in operation and storing thermal energy in the ground after the operation period of the system. These two mechanisms should be considered in the evaluation of long-term performance of the BHE. The developed simulation model is tested for the performance improvement through parallelization. The computational efficiency of the developed simulation model is considerably increased in direct proportion to the number of the processors. The model is then applied to evaluate the performance of the KIGAM GHP system for a 25-year operation. The temperature of the ground in the vicinity of BHEs is gradually increased with time because of the imbalance of the injected/extracted thermal power to/from the ground during the cooling/heating seasons. It causes the decrease of the efficiency of the system during the cooling seasons for the long-term operation. Finally, a versatile simulation model is developed to simulate not only the vertical closed-loop GHP system, but also the standing column well and open-loop GHP systems. A method to generate an unstructured Voronoi grid for its use in simulations of geothermal heat pump systems is presented. A series of codes is developed to create Voronoi cell center points that are placed at specific positions for well- or pipe-shaped Voronoi grids, to generate a three-dimensional grid from generated Voronoi cell vertices, and to visualize the generated grid and simulation results by ParaView. AMESH program is used to calculate the x- and y-coordinates of the Voronoi cell vertices from the Voronoi cell center points. The developed series of codes can generate the desired form of the grid. The generated grid is tested with confidence through simulations of water production/injection from/to the various kinds of the geothermal wells.Abstract i Contents iv List of Tables vii List of Figures viii Chapter 1. Introduction 1 1.1. Backgrounds 1 1.2. Objectives 6 Chapter 2. Simulation modeling of a borehole heat exchanger 10 2.1. Introduction 10 2.2. Method 11 2.2.1. Physical background 11 2.2.2. Simulation model development 12 2.3. Study area 20 2.4. Model setup and validation 25 2.4.1. Model setup 25 2.4.2. Model validation 26 2.5. Sensitivity analysis 31 2.6. BHE design evaluation 33 2.6.1. Criteria and guidelines for the design evaluation 34 2.6.2. Simulation results for the base case 36 2.6.3. Simulation results for the modified cases 40 2.6.4. Cost analysis 44 2.7. Summary and conclusion 46 Chapter 3. Simulation modeling of multiple borehole heat exchangers 48 3.1. Introduction 48 3.2. Method 49 3.3. Speedup test 60 3.4. Evaluation of the long-term performance of the KIGAM GHP system 62 3.4.1. Study area 62 3.4.2. Model setup 64 3.4.3. Guidelines 66 3.4.4. Results and discussion 69 3.5. Summary and conclusion 75 Chapter 4. Voronoi grid for simulation of geothermal heat pump systems 77 4.1. Introduction 77 4.2. Method 83 4.3. Results 89 3.4.1. Examples of generated grids 89 3.4.1. Examples of generated grids 92 4.4. Conclusion 100 Chapter 5. Discussion 102 Chapter 6. Summary and conclusions 105 References 107 Abstract (in Korean) 115Docto

Educational Dimension

Збiрник наукових праць «Освiтнiй вимiр» мiстить матерiали, присвяченi висвiтленню теоретико-практичних проблем педагогiки вищої та загальноосвiтньої школи, становлення i розвитку освiтньої парадигми, iнтеграцiї психолого-педагогiчних чинникiв в органiзацiю навчально-виховного процесу. Випуск мiстить матерiали шостого мiжнародного семiнару «Хмарнi технологiї в освiтi» (Кривий Рiг, Україна, 21 грудня 2018 року). Оригiнальна онлайн публiкацiя — у 2433 томi CEUR Workshop Proceedings (CEUR-WS.org, ISSN 1613–0073).The collection of scientific works "Educational Dimension" contains materials devoted to the coverage of theoretical and practical problems of higher and secondary school pedagogy, the formation and development of the educational paradigm, the integration of psychological and pedagogical factors in the body. The issue contains materials of the sixth international seminar "Cloud technologies in education" (Kryvyi Rih, Ukraine, December 21, 2018). Original online publication - in 2433 volumes of CEUR Workshop Proceedings (CEUR-WS.org, ISSN 1613–0073)

The marine geology of Mossel Bay, South Africa

Includes bibliographical references.This thesis presents work undertaken to better understand the complex evolution of the terrestrial landscape now submerged by high sea levels offshore of Mossel Bay along the South Coast of South Africa. Three marine geophysical surveys and scuba diving were used to examine evidence of past sea-level fluctuations and interpret geological deposits on the seafloor. Additional geological mapping of coastal outcrops was carried out to link land and sea features and rock samples were dated using Optically Stimulated Luminescence (OSL). Geophysical investigations include a regional seismic survey extending from Still Bay in the west to Buffels Bay in the east out to a maximum water depth of 110 m; a high-resolution investigation of the Mossel Bay shelf using multibeam bathymetry, side-scan sonar and sub-bottom profiling; and a shallow seismic pinger survey of Swartvlei, the most prominent coastal lake in the Wilderness Embayment. This study presents 9 discrete seismic sequences, and describes major offshore geomorphic features such as submerged sea cliffs, palaeo-coastal zones and fluvial systems. Oscillation in sea level between ca. 2.7 and 0.9 Ma likely resulted in the formation of the prominent -45 m terrace, which separates a relatively steep inner from a low-gradient mid shelf. Beach and dune deposits span from Marine Isotope Stage 15 (MIS 15) (582 ka) to Recent based on an age model that integrates OSL ages and the established eustatic sea-level record. The most prominent deposits date from the MIS 6 glacial to MIS 5 interglacial periods and include incised lowstand river channels and regressive aeolianites that extended at least 10 km inland from their associated palaeoshorelines. The MIS 5 deposits include transgressive beachrock, an extensive foreshore unit which prograded on the MIS 5e highstand, and regressive beach and dune deposits on the shelf associated with the subsequent fall in sea level. MIS 4 lowstand incised river channels were infilled with sediment truncated during rapid landward shoreface migration at the MIS 4 termination. Lowenergy, back-barrier MIS 4/3 sediments are preserved as a result of overstepping associated with meltwater pulses of the MIS 2 termination. The MIS 1 sediment wedge comprises reworked sediment and is best developed on the inner shelf. Holocene highstand sedimentation continues to prograde. Accommodation space for coastal deposits is controlled by antecedent drainage pathways and the gradient of the adjacent inner continental shelf. The geological deposits on the emergent shelf indicate a greatly expanded glacial coastal plain that potentially received more rain feeding low-gradient meandering rivers and wetland lakes. These extensive wetland environments provided a rich source of diverse food types which along with abundant marine resources on the shoreline made the Southern Coastal Plain an ideal habitat for our ancestors

A GIS-based open source pre-processor for georesources numerical modeling

TOUGH2 is an integral finite differences numerical simulator for non-isothermal multiphase flow in fractured porous media, which can manage complex spatial discretizations. Numerical simulation accuracy is affected, among other things, by grid resolution. Increasing the grid resolution requires computational and operating costs depending on the number of nodes and variables processed. The complexity of the management of the model increases when unstructured grids and local refinement are used. In order to improve the management and optimize the activities to update the model, an open source pre-processor has been developed using the open source codes GRASS GIS, SQLite and AMESH. Operations such as domain discretization, rock type assignment and mesh file generation have been automatized. Graphical interfaces allow for a user-friendly utilization. Operating errors and time required by pre-processing activities to generate and update locally refined unstructured grids have been reduced. Productivity in numerical modeling has been substantially increased