Long-distance and high-impact wind farm wake effects revealed by SAR: a global-scale study

Wind, as a clean and sustainable source of energy, has witnessed significant growth in recent years. However, with a growing number of wind farms authorised, constructed and commissioned, the wake effect (the reduced wind speed caused by upstream wind farms) is emerging as a pressing concern for both farm owners and policymakers. Here, to systematically and comprehensively investigate the wake effects in real-world wind farms, we analyse the wind speed retrieved from 7122 Sentinel 1A/B SAR images spanning over three years, encompassing more than 60 large-scale wind farms across Europe and Asia. Our study reveals that long-distance wakes can propagate more than 100 km. Additionally, we identify that wake effects lead to, on average, a 1.204 m/s (or 12.4%) speed reduction for downstream wake-affected areas. We envisage that our quantitative findings can provide vital support to wake-related planning and legislation for future wind energy projects where wind power plants are expected to be in close proximity

Integration of POD-DEIM to Flow-based Upscaling Method in Reservoir Simulation Model Order Reduction

This thesis proposes a new workflow for mitigating computational effort in reservoir simulation by integrating two methods of complexity reduction used independently in reservoir applications: flow-based upscaling and projection-based reduced-order modeling. The objective of this thesis is to combine the strengths of the discrete interpolation technique (DEIM), such as the selection of few interpolation points, to leverage the permeability calculation and averaging obtained from flow-based upscaling, in order to increase the production rate accuracy of the modified upscaled reservoir model. The new proposed methodology uses 6 specific one-layer models of the SPE 10 Comparative Project as the base models: (1) Layer 1, 10, 30 from the Tarbert Formation, and (2) Layer 50, 60, and 70 from the Upper Ness formation. Besides, 2 3D models of the SPE 10, layer 1-6, and layer 50-55 is also used for the case study. All cases are two-phase oil-water saturated black oil reservoir model with no gas. A normal 5-spot producing scheme is used with 4 producing wells at four corners and the water injection well located at the center of the reservoir. To prove the concept and assess the efficiency of the new integrated methodology, the study is divided into three parts. First, solely upscaling is applied by conducting arithmetic, harmonic, and flow-based upscaling. Second, model reduction is performed by applying the Proper-Orthogonal Decomposition POD-DEIM calculation on the residuals of the fine-scale model results and obtain the DEIM index. Lastly, the proposed new method utilized POD-DEIM selection results and incorporated it into the flow-based upscaling permeability modification. In the 2D cases, 2 by 2 upscaling is utilized to upscale the model. For the 3D cases, a 2 by 2 by 2 upscaling is performed. The flow-based upscaling model has a production error of approximately 20% compared with the original fine-scale model. However, after utilizing different numbers of DEIM index points to modify the permeability, the new model has a production error decreases of approximately 5% on most of the wells. The remaining wells have a production error similar to the flow-based model. Overall, the integration of POD-DEIM and flow-based upscaling has been seen to decrease the production error of upscaled model and can be used for decreasing model complexity while maintaining better production matching accuracy than before

Phase Field Model for Non-equilibrium Interface Conditions

This article presents a new phase-field formulation for non-equilibrium interface conditions in rapid phase transformations. With a particular way of defining concentration fields, the classical sharp and diffuse (thick) interface theories are unified into the present phase-field model. Each point inside the diffuse interface is comparable to the classical sharp interface model, governed by phase boundary migration and short-range atomic exchanges and connected by long-range diffusion. Their thermodynamic forces and fluxes are following the Onsager reciprocal relation and consistent with the classical irreversible thermodynamics. Furthermore, we establish the balance of driving forces and energy dissipations for both the diffuse interface and the single point inside it. The model is then validated by rapid solidification of Al-Cu alloys. With an effective mobility of considering non-equilibrium long-range diffusion, the model represents the main characteristics of non-equilibrium interface kinetics, i.e., solute trapping and solute drag. Especially, we reproduce the complete trapping at the high-velocity regime and provide a thermodynamic consistent description of the partial drag phenomena at the low-velocity region. Moreover, the dissipation analysis indicates that even the far-from-equilibrium diffuse interface is composed of numerous representative volume elements near the equilibrium, providing a new understanding of non-equilibrium interfaces.Comment: 51 Pages, 122 Equations, 12 Figure