adeline Montlaur | Universitat Politecnica de Catalunya (original) (raw)

Papers by adeline Montlaur

Sustainability

An OpenFOAM computational fluid dynamics model setup is proposed for simulating thermally driven ... more An OpenFOAM computational fluid dynamics model setup is proposed for simulating thermally driven winds in mountain–valley systems. As a first step, the choice of Reynolds Averaged Navier–Stokes k−ε turbulence model is validated on a 3D geometry by comparing its results vs. large-eddy simulations reported in the literature. Then, a numerical model of an idealised 2D mountain–valley system with mountain slope angle of 20° is developed to simulate thermally driven winds. A couple of top surface boundary conditions (BC) and various combinations of temperature initial conditions (IC) are tested. A transient solver for buoyant, turbulent flow of incompressible fluids is used. Contrary to classical approaches where buoyancy is set as a variable of the problem, here temperature linearly dependent with altitude is imposed as BC on the slope and successfully leads to thermally driven wind generation. The minimum fluid domain height needed to properly simulate the thermally driven winds and th...

Simulations of Thermal Wind Formation in Idealised Mountain-Valley Systems Using Openfoam

SSRN Electronic Journal

Proceedings of the VII European Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS Congress 2016), 2016

Exploring novel renewable energy resources such as thermal winds in mountainous areas and valleys... more Exploring novel renewable energy resources such as thermal winds in mountainous areas and valleys is critical to reduce the energy production from fossil fuels and thus mitigating climate change. These winds occur due to thermal gradients and related buoyancy effects. Basically, the latter are mainly associated with the diurnal heating-cooling cycles of the lower layers of the atmosphere. Thermal winds usually develop by convection over complex terrains of different scales, and they invert their direction twice a day, driven by the emergence and dissipation of temperature inversions. Namely, these winds will blow up-valley (anabatic winds), or from the plain to the mountain massif during day-time. Contrary, during night-time, these winds will blow down-valley (katabatic winds), or from the mountain massif to the plain. Former investigations have shown that thermal winds can reach comparably high speeds [1], which could be interesting for wind energy applications. Moreover, in compar...

Gas – liquid two - phase flows dominated by capillary forces occur in countless modern industrial... more Gas – liquid two - phase flows dominated by capillary forces occur in countless modern industrial applications. Some examples can be found in normal gravity (mixing process, chemical reactions, emulsion technology, materials synthesis, medical science, persona l care products, etc), as well as in space - based systems (life - support systems for human exploration, thermal management systems, propulsion systems, chemical contactors, space bioreactors, etc). A better understanding and an improvement of two - phase flows generation techniques are thus mandatory for the optimal development of these technologies, both in normal and reduced - gravity environments. In the past, great efforts have been conducted to fulfil this goal, and several methods have been proposed, aiming to generate and control two - phase flows in a very accurate way. T-junction bubble generators have arisen as an efficient method providing trains of bubbles, immersed into a continuous liquid, with small dispersion...

International Journal of Numerical Analysis and Modeling, 2014

The discontinuous Galerkin Interior Penalty Method with solenoidal approximations proposed in [13... more The discontinuous Galerkin Interior Penalty Method with solenoidal approximations proposed in [13] for the incompressible Stokes equations is analyzed. Continuity and coercivity of the bilinear form are proved. A priori error estimates, with optimal convergence rates, are derived. 2D and 3D numerical examples with known analytical solution corroborate the theoretical analysis.

This paper studies trade-offs between flight and passenger delays and fairness when assigning del... more This paper studies trade-offs between flight and passenger delays and fairness when assigning delay pre-tactically (on-ground at origin airport) due to reduced airport capacity. The paper also defines and analyses efficiency-fairness tradeoffs. The optimisation model is based on the ground holding problem and uses various objective functions: total delay for flights (considering reactionary delay), total delay for passengers (considering outbound connections), and deviation from a Ration By Schedule solution (to get a measure of the fairness of the solution). The scenario considered takes place at Paris Charles de Gaulle airport, a busy European hub airport, and includes realistic values of traffic.

Aiming to a more collaborative demand and capacity balancing (DCB), in the scope of trajectory ba... more Aiming to a more collaborative demand and capacity balancing (DCB), in the scope of trajectory based operations, this paper presents an approach that takes alternative trajectories into a DCB optimization algorithm. These alternative trajectories are generated by the airspace users for those flights traversing hotspots (i.e. sectors with demand above capacity), which are predicted by the Network Manager. The trajectories consider lateral re-routings and/or vertical avoidance of all detected hotspots, which, along with different types of delay measures (including linear holding and in-flight delay recovery), are then integrated as a whole into a centralized optimization model to manage the traffic flow under a set of static scheme of airspace capacities. The combination of trajectory options and distribution of delays are hence optimized with the objective of minimizing the total deviation with regard to airspace users’ preferences (taking into account the fuel consumption, route cha...

Alaskan wave and river hydrokinetic energy resource assessment, river energy converter testing and surface debris mitigation performance

Sustainability, 2021

Recently, there has been much interest in measuring the environmental impact of short-to-medium-h... more Recently, there has been much interest in measuring the environmental impact of short-to-medium-haul flights. Emissions of CO2 are usually measured to consider the environmental footprint, and CO2 calculators are available using different types of approximations. We propose analytical models calculating gate-to-gate CO2 emissions and travel time based on the flight distance and on the number of available seats. The accuracy of the numerical results were in line with other CO2 calculators, and when applying an analytical fitting, the error of interpolation was low. The models presented the advantage with respect to other calculators of being sensitive to the number of available seats, a parameter generally not explicitly considered. Its applicability was shown in two practical examples where emissions and travel time per kilometre were calculated for several European routes in a simple and efficient manner. The model enabled the identification of routes where rail would be a viable a...

Transportation Research Part B: Methodological, 2020

This paper proposes a collaborative air traffic flow management (ATFM) framework, in the scope of... more This paper proposes a collaborative air traffic flow management (ATFM) framework, in the scope of trajectory based operations, aiming to improve the costefficiency for airspace users (AUs) when facing ATFM regulations. The framework consists of four modules. The first one involves the AUs initially scheduling their preferred trajectories for all their flights. Based on this initial demand, the second module (assumed to be on the Network Manager-NM-side) detects time-varying hotspots (i.e. overloaded sectors along the day). In the third module, hotspot information is shared back to the AUs who plan alternative trajectory options to avoid crossing these congested airspace volumes (in the lateral and vertical domain); as well as providing to the NM different pre-tactical delay management preferences (including ground holding, linear holding, air holding and pre-tactical delay recovery); based on their internal cost breakdown structures. Incorporating all these potential combined options, the last module computes the best trajectory selections and the optimal distribution of delay assignments, such that the cost deviation from the initial status (all the user-preferred trajectories) is minimized. This model is formulated as mixed integer linear programming (MILP) and validated by a real-world case study focused on 24 hours of traffic over the French airspace. Results using the proposed framework suggest a significant system delay reduction by nearly 97% over the existing method, whilst yielding an average of less than 100 kg extra fuel consumption and 50 Euro extra route charges for the 11% flights diverted to their alternative trajectories.

Journal of Air Transport Management, 2020

This paper studies trade-offs between efficiency (performance) and fairness (equity), when assign... more This paper studies trade-offs between efficiency (performance) and fairness (equity), when assigning ATFM delay pre-tactically (on-ground at origin airport) due to reduced airport capacity at destination. Delay is assigned as the result of the optimisation of a deterministic multi-objective problem considering flight and passenger perspectives when defining objectives of performance and fairness. Two optimisation cases are presented: one where objectives are based on flight metrics, and another one where they are based on passenger metrics. The paper defines and analyses efficiency-fairness trade-offs: the concepts of price of fairness for flights and passengers are defined as the percentage of efficiency loss due to the consideration in the optimisation of fairness; whereas the price of efficiency is considered as the fairness loss relative to the maximum value of the fairness metric, when considering flight or passenger delay in the optimisation. The optimisation model is based on the ground holding problem and uses various objective functions. For performance, total delay for flights (considering reactionary delay), and total delay for passengers (considering outbound connections) are defined. For fairness, the deviation of flight arrivals from a Ration By Schedule solution, and the deviation of delay experienced by passengers with respect to the one obtained in an RBS situation are used. An illustrative application on traffic at Paris Charles de Gaulle airport, a busy European hub airport, and including realistic values of traffic is modelled. A comprehensive trade-off analysis is presented. Results show, how in some cases, gains on one stakeholder can be achieved without implying any detriment on the other one. Passengers are more sensitive to the optimisation and hence, their consideration when assigning delay is recommended. Further research should explore how to combine flight and passenger indicators in the optimisation and consider how the lack of data availability could be mitigated.

Energy, 2019

This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

Microgravity Science and Technology, 2018

In this work, we study the influence of the contact angle boundary condition on 3D CFD simulation... more In this work, we study the influence of the contact angle boundary condition on 3D CFD simulations of the bubble generation process occurring in a capillary T-junction. Numerical simulations have been performed with the commercial Computational Fluid Dynamics solver ANSYS Fluent v15.0.7. Experimental results serve as a reference to validate numerical results for four independent parameters: the bubble generation frequency, volume, velocity and length. CFD simulations accurately reproduce experimental results both from qualitative and quantitative points of view. Numerical results are very sensitive to the gas-liquidwall contact angle boundary conditions, confirming that this is a fundamental parameter to obtain accurate CFD results for simulations of this kind of problems.

Transportation Research Part C: Emerging Technologies, 2017

This paper compares different optimization strategies for the minimization of flight and passenge... more This paper compares different optimization strategies for the minimization of flight and passenger delays at two levels: pretactical, with on-ground delay at origin, and tactical, with airborne delay close to the destination airport. The optimization model is based on the ground holding problem and uses various cost functions. The scenario considered takes place in a busy European airport and includes realistic values of traffic. A passenger assignment with connections at the hub is modeled. Statistical models are used for passenger and connecting passenger allocation, minimum time required for turnaround and tactical noise; whereas uncertainty is also introduced in the model for tactical noise. Performance of the various optimization processes is presented and compared to ration by schedule results.

Numerical Study of 2D Vertical Axis Wind and Tidal Turbines with a Degree-Adaptive Hybridizable Discontinuous Galerkin Method

Springer Tracts in Mechanical Engineering, 2015

This work presents a 2D study of vertical axis turbines with application to wind or tidal energy ... more This work presents a 2D study of vertical axis turbines with application to wind or tidal energy production. On the one hand, a degree-adaptive Hybridizable Discontinuous Galerkin (HDG) method is used to solve this incompressible Navier–Stokes problem. The HDG method allows to drastically reduce the coupled degrees of freedom (DOF) of the computation, seeking for an approximation of the solution that is defined only on the edges of the mesh. The discontinuous character of the solution provides an optimal framework for a degree-adaptive technique. Degree-adaptivity further reduces the number of DOF in the HDG computation by means of degree-refining only where more precision is needed. On the other hand, the finite volume method of ANSYS® is used to validate and compare the obtained results.

A Set-based Approach to Facilitate Distributed Design

ABSTRACT Thesis (M.S.)--State University of New York at Buffalo, 2002. Includes bibliographical r... more ABSTRACT Thesis (M.S.)--State University of New York at Buffalo, 2002. Includes bibliographical references (leaves 70-71). Photocopy of typescript.

Journal of Wind Engineering and Industrial Aerodynamics, 2012

Speed-up over topography has long been recognised as significant for structural design and wind e... more Speed-up over topography has long been recognised as significant for structural design and wind energy applications. Here wind flow over cliffs that have a sawtooth plan are studied for speed-up effects under different wind directions. The study undertook PIV measurements to document the mean and turbulence changes in three dimensions for simulated atmospheric boundary layer flow in the University of Sydney BLWT. As the flow approaches the cliffs, it accelerates and moves up to pass the obstruction and generates two strong vortices on the top surface of the cliff. Small changes in wind direction not only lead to significantly different speed-up ratios, but also influence the location of the vortices and the level of turbulence. The complexity of the flow field is revealed in this unique three-dimensional study.