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The parabolic equation methods are advantageous in simulating under small time frames because of their low computational complexity. Because of this they are also feasible to implement on low end hardware. Due to the parabolic approximation they are based on, much work exists on improving the error introduced from the approximation. In this publication, further effort is put into developing these methods and the result from a master thesis at Tietoevry are presented. An in-house algorithm for evaporation duct propagation has been altered to improve the terrain modeling and to include range varying refractivity in a split step Fourier method called the discrete mixed Fourier transform. Previously only the piecewise linear shift map was utilized for terrain modeling which is known to become unstable at propagation angles exceeding around 15 degrees from the horizontal. By utilizing a hybrid method between piecewise linear shift map and knife edge method the stability issues are partially avoided, hence the solutions generated with the hybrid method are stable for a larger range of slope angles than with only using piecewise linear shift map. The range varying refractivity was included in the discrete mixed fourier transform by indexing making it possible to simulate dynamic evaporation duct heights. The report starts with a review of the theoretical foundation that the algorithm is built upon. Secondly, a logical list of steps outlines the altered algorithm. To conclude, the changes to the code are presented and discussed with the new results together with remarks on possible future improvements and current problems with the algorithm.

Magnetosheath jets represent localized enhancements in dynamic pressure observed within the magnetosheath. These energetic entities, carrying excess energy and momentum, can impact the magnetopause and disrupt the magnetosphere. Therefore, they play a vital role in coupling the solar wind and terrestrial magnetosphere. However, our understanding of the morphology and formation of these complex, transient events remains incomplete over two decades after their initial observation. Previous studies have relied on oversimplified assumptions, considering jets as elongated cylinders with dimensions ranging from $0.1\, R_{\rm E}$ to $5\, R_{\rm E}$ (Earth radii). In this study, we present simulation results obtained from Amitis, a high-performance hybrid-kinetic plasma framework (particle ions and fluid electrons) running in parallel on graphics processing units (GPUs) for fast and more environmentally friendly computation compared to CPU-based models. Considering realistic scales, we present the first global, three-dimensional (3D in both configuration and velocity spaces) hybrid-kinetic simulation results of the interaction between solar wind plasma and the Earth. Our high-resolution kinetic simulations reveal the 3D structure of magnetosheath jets, showing that jets are far from being simple cylinders. Instead, they exhibit intricate and highly interconnected structures with dynamic 3D characteristics. As they move through the magnetosheath, they wrinkle, fold, merge, and split in complex ways before a subset reaches the magnetopause.

An experiment-supported simulation process chain is set up to perform numerical forced response analyses on a transonic high-pressure compressor front stage at varying operating conditions. A wake generator is used upstream of the rotor to excite a specific resonance within the operating range of the compressor. Thereby, extensive aerodynamic and structural dynamic experimental data, obtained from state-of-the-art rig testing at the Transonic Compressor Darmstadt test facility at the Technical University of Darmstadt, are used to validate numerical results and ensure realistic boundary conditions. In the course of this, five-hole-probe measurements at steady operating conditions close to the investigated resonance enable a validation of the steady aerodynamics. Subsequently, numerically obtained aeroelastic quantities, such as resonance frequency, and damping, as well as maximum alternating blade stresses and tip deflections, are compared to experimental blade tip timing data. Experimental trends in damping can be confirmed and better explained by considering numerical results regarding the aerodynamic wall work density and secondary flow phenomena. The influence of varying loading conditions on the resonance frequency is not observed as distinctly in numerical, as in experimental results. Generally, alternating blade stresses and deflections appear to be significantly lower than in the experiments. However, similar to the aerodynamic damping, numerical results contribute to a better understanding of experimental trends. The successive experimental validation shows the capabilities of the numerical forced response analysis setup and enables the highlighting of challenges and identification of potential further adaptations., QC 20240708

Context. Modified Newtonian dynamics (MOND) is a promising alternative to dark matter. To further test the theory, there is a need for fluid- and particle-dynamics simulations. The force in MOND is not a direct particle-particle interaction, but derives from a potential for which a nonlinear partial differential equation (PDE) needs to be solved. Normally, this makes the problem of simulating dynamical evolution computationally expensive. Aims. We intend to develop a fast particle-mesh (PM) code for MOND (the AQUAL formalism). Methods. We transformed the nonlinear equation for MOND into a system of linear PDEs plus one algebraic equation. An iterative scheme with the fast Fourier transform (FFT) produces successively better numerical approximations. Results. The algorithm was tested for dynamical systems in MOND where analytical solutions are known: the two-body problem, a body with a circular ring, and a spherical distribution of particles in thermal equilibrium in the self-consistent potential. Conclusions. The PM code can accurately calculate the forces at subpixel scale and reproduces the analytical solutions. Four iterations are required for the potential, but when the spatial steps are small compared to the kernel width, one iteration is suffices. The use of a smoothing kernel for the accelerations is inevitable in order to eliminate the self-gravity of the point particles. Our PDE solver is 15 to 42 times as slow as a standard Poisson solver. However, the smoothing and particle propagation takes up most of the time above one particle per 10 3 pixels. The FFTs, the smoothing, and the propagation part in the code can all be parallelized., Mathematical Physics, RST/Fundamental Aspects of Materials and Energy

The grain texture of the as-printed material evolves during the laser-based powder bed fusion (PBF-LB) process. The resulting mechanical properties are dependent on the obtained grain texture and the properties vary depending on the chosen process parameters such as scan velocity and laser power. A coupled 2D Cellular Automata and Finite Element model (2D CA-FE) is developed to predict the evolution of the grain texture during solidification of the nickel-based superalloy 625 produced by PBF-LB. The FE model predicts the temperature history of the build, and the CA model makes predictions of nucleation and grain growth based on the temperature history. The 2D CA-FE model captures the solidification behavior observed in PBF-LB such as competitive grain growth plus equiaxed and columnar grain growth. Three different nucleation densities for heterogeneous nucleation were studied, 1 × 1011, 3 × 1011, and 5 × 1011. It was found that the nucleation density 3 × 1011 gave the best result compared to existing EBSD data in the literature. With the selected nucleation density, the aspect ratio and grain size distribution of the simulated grain texture also agrees well with the observed textures from EBSD in the literature., Validerad;2023;Nivå 2;2023-11-06 (joosat);Part of Special Issue: Multi-Scale Simulation of Metallic Materials (2nd Edition)CC BY 4.0 LicenseFunder: EU Just Transition Fund and the Swedish Agency for Economic and Regional Growth (FINAST project, grant number 20358499)

This paper presents a numerical aerodynamic study of the stall characteristics and flow separation mechanismsof a blended wing body unmanned aerial vehicle being developed at KTH Royal Institute of Technologyand proposes a bio-inspired leading-edge modification to control the separation mechanism andimprove the aerodynamic performance of the aircraft at high angles of attack. A numerical study of theaircraft was performed at cruise speed, corresponding to Reynold’s number of 1.3x106, employing an UnsteadyReynolds Averaged Navier-Stokes solver with the Spalart-Allmaras turbulence model. Numericalresults indicated that the aircraft is characterized by the presence of an unstable longitudinal vortex – visibleat the stall angle of 9 deg – which breaks up at an angle of attack of 10 deg, resulting in an unsteady,full-chord stall cell in the mid-span region of the wing section. To mitigate this phenomenon, a modificationto the leading edge between 0.4 m and 1.8 m wing spans was implemented inspired by the geometryof the nose of a porpoise whale, effectively generating a porpoise (hump) leading-edge inboard section.Preliminary numerical results indicate an increase in stall angle of attack to ∼13 deg and an in maximumlift coefficient to ∼1.0. Furthermore, the porpoise hump allowed controlling the stall behavior of the aircraftby enforcing a wing tip, trailing-edge separation stall achieved by the generation of an extended flowacceleration region at the leading edge., QC 20231016

When people use rule-based integration of abstracted cues to make multiple-cue judgments they tend to default to linear additive integration of the cues, which may interfere with efficient learning in non-additive tasks. We hypothesize that this effect becomes especially pronounced when cues are presented numerically rather than verbally, because numbers elicit expectations about a task with a simple numerical solution that can be appropriately addressed by linear and additive integration. This predicts that, relative to a verbal format, a numerical format should be advantageous for learning in additive tasks, but detrimental for learning in non-additive tasks. In two experiments, we find support for the hypothesis that a verbal format can improve learning in non-additive tasks. The division-of-labor between cognitive processes observed in previous research (Juslin et al., 2008), with cue abstraction in additive tasks and exemplar memory in non-additive tasks, was only present in conditions with numeric information and may therefore in part be driven by the use of numeric formats. This illustrates how surface characteristic of stimuli can elicit different priors about the nature of the variables and the generative model that produced the cues and the criterion. We fitted cue-abstraction and exemplar algorithms by PNP-modeling (Sundh et al., 2021). At the end of training both cue abstraction and exemplar memory processes primarily involved exact analytic processes marred by occasional error, rather than the noisy and approximate intuitive processes typically assumed in previous studies – specifically, cue abstraction was primarily implemented by number crunching and exemplar memory by rote memorization.

Context. The characteristic variability of cool giants and supergiants is attributed to a combination of stellar pulsation and large-scale convective flows. Full 3D radiation-hydrodynamical modelling is an essential tool for understanding the nature of these dynamical processes. The parameter space in our 3D model grid of red giants has expanded in recent years. These models can provide many insights on the nature and properties of the pulsations, including the interplay between convection and pulsations. Aims. We treat 3D dynamical models of asymptotic giant branch (AGB) stars and red supergiants (with current masses 1 M-circle dot <= M-* <= 12 M-circle dot) similar to observational data. We aim to explore the relation between stellar parameters and the properties of the self-excited pulsations. Methods. Output from global 'star-in-a-box' models computed with the CO5BOLD radiation-hydrodynamics code were analysed, particularly in regards to the pulsation properties, to find possible correlations with input and emergent stellar parameters. The fast Fourier transform was applied to spherically averaged mass flows to identify possible radial pulsation periods beneath the photosphere of the modelled stars. Stellar parameters were investigated for correlations with the extracted pulsation periods. Results. We find that the pulsation periods varied with the stellar parameters in good agreement with the current expectations. The pulsation periods follow Ritter's period-mean density relation well and our AGB models agree with period-luminosity relations derived from observations. A mass estimate formula was derived from the 3D models, relating the stellar mass to the fundamental mode pulsation period and the stellar radius. Conclusions. While the non-linearity of the interplay between the self-excited pulsations and the self-consistent convection complicates analyses, the resulting correlations are in good agreement with respect to current theoretical and observation

Design of atomizers for gas-turbine purposes are an important ordeal. The per-formance of the atomizer directly impacts the efficiency of the gas-turbine, andconsequently, the energy extracted from the turbine. Furthermore, the design ofthe atomizer can have an impact on reducing toxic emissions. On a global scale,gas-turbines can be considered crucial for the transition to renewable energy. Forengineers, designing of atomizers are however challenging. Turbulent flow, multi-phase interaction and chemical reactions are some of the complex physics involvedwhich has to be taken into consideration when designing the atomizer. Engineerstraditionally uses experimental testing for investigation of designs, and it is still verymuch a useful methodology. However, numerical simulations and CFD have recentlygained popularity due to being a more cost-effective methodology. In this work, theprocedure for designing a prefilm atomizer involving CFD (single phase model andmulti phase model) and experimental testing is documented. The details of the twonumerical models (a single phase model and a multi phase model) has been doc-umented as well as the experimental setup. The single phase model is used for aparametric study and experimental testing is used for evaluation of designs. Themulti phase model is aimed to replicate the experimental results. The validity ofthe numerical models and the experimental setup are discussed, and possible mod-ifications of the methodology for future studies are suggested. Finally, suggestionsfor how the prefilmer should be designed is suggested.

To self-consistently model galactic properties, reionization of the intergalactic medium, and the associated 21-cm signal, we have developed the algorithm polar by integrating the one-dimensional radiative transfer code grizzly with the semi-analytical galaxy formation code L-Galaxies 2020. Our proof-of-concept results are consistent with observations of the star formation rate history, UV luminosity function, and the CMB Thomson scattering optical depth. We then investigate how different galaxy formation models affect UV luminosity functions and 21-cm power spectra, and find that while the former are most sensitive to the parameters describing the merger of haloes, the latter have a stronger dependence on the supernovae feedback parameters, and both are affected by the escape fraction model.

Recent observations of the Earth’s exosphere revealed the presence of an extended hydrogenic component that could reach distances beyond 40 planetary radii. Detection of similar extended exospheres around Earth-like exoplanets could reveal crucial facts in terms of habitability. The presence of these rarified hydrogen envelopes is extremely dependent on the planetary environment, dominated by the ionizing radiation and plasma winds coming from the host star. Radiation and fast wind particles ionize the uppermost layers of planetary atmospheres, especially for planets orbiting active, young stars. The survival of the produced ions in the exosphere of such planets is subject to the action of the magnetized stellar winds, particularly for unmagnetized bodies. In order to address these star–planet interactions, we have carried out numerical 2.5D ideal MHD simulations using the PLUTO code to study the dynamical evolution of tenuous, hydrogen-rich, Earth-like extended exospheres for an unmagnetized planet, at different stellar evolutionary stages: from a very young, solar-like star of 0.1 Gyr to a 5.0 Gyr star. For each star–planet configuration, we show that the morphology of extended Earth-like hydrogen exospheres is strongly dependent on the incident stellar winds and the produced ions present in these gaseous envelopes, showing that the ionized component of Earth-like exospheres is quickly swept by the stellar winds of young stars, leading to large bow shock formation for later stellar ages., Ministerio de Economía y Competitividad (MINECO), Unidad Deptal. de Astronomía y Geodesia, Fac. de Ciencias Matemáticas, FALSE, pub

Reseñado en: Sacristán, Enrique. Una miniluna acompañará a la tierra durante las próximas décadas. Retrieved Feb 13, 2023, from https://www.agenciasinc.es/Noticias/Una-miniluna-acompanara-a-la-Tierra-durante-las-proximas-decadas, Context. The near-Earth orbital space is shared by natural objects and space debris that can be temporarily captured in geocentric orbits. Short-term natural satellites are often called mini-moons. Reflectance spectroscopy can determine the true nature of transient satellites because the spectral signatures of spacecraft materials and near-Earth asteroids (NEAs) are different. The recently discovered object 2022 NX1 follows an Earth-like orbit that turns it into a recurrent but ephemeral Earth companion. It has been suggested that 2022 NX1 could have an artificial origin or be lunar ejecta. Aims. Here, we use reflectance spectroscopy and N-body simulations to determine the nature and actual origin of 2022 NX1. Methods. We carried out an observational study of 2022 NX1, using the OSIRIS camera spectrograph at the 10.4 m Gran Telescopio Canarias, to derive its spectral class. N-body simulations were also performed to investigate how it reached NEA space. Results. The reflectance spectrum of 2022 NX1 is neither compatible with an artificial origin nor lunar ejecta; it is also different from the V type of the only other mini-moon with available spectroscopy, 2020 CD3. The visible spectrum of 2022 NX1 is consistent with that of a K-type asteroid, although it could also be classified as an Xk type. Considering typical values of the similar albedo of both K-type and Xk-type asteroids and its absolute magnitude, 2022 NX1 may have a size range of 5 to 15 m. We confirm that 2022 NX1 inhabits the rim of Earth’s co-orbital space, the 1:1 mean-motion resonance, and experiences recurrent co-orbital engagements of the horseshoe-type and mini-moon events. Conclusions. The discovery of 2022 NX1 confirms that mini-moons can be larger than a few meters and also that they belong to a heterogeneous population in terms of surface composition., Ministerio de Ciencia e Innovación (MICINN), Gobierno de Canarias, Sección Departamental de Física de la Tierra y Astrofísica (Ciencias Matemáticas), Fac. de Ciencias Matemáticas, TRUE, pub

We investigate the accuracy of the analytical expressions for the magnetostatic demagnetization tensor for three different geometries by comparing these to the dipole field at far-away distances. We consider a prism, tetrahedron and cylindrical tile geometry. We show that for the prism and tetrahedron tiles the median relative error compared to the dipole field reaches below 10−7 at 200 tile radii away from the generating tile, while the cylindrical tile has a median relative error of about 10−5 at this distance. Even at a distance of 104 tile radii the relative error is below 10−2 for all tiles, also when single precision is used to calculate the magnetic field. This shows that the demagnetization tensor is an accurate way of calculating the stray magnetic field also for far-away distances.

As market growth projections for Urban Air Mobility vehicles (UAMs) skyrocket, their presence in urban environments is likely to become increasingly prevalent, as will their noise. This creates a disturbance to both humans and wildlife, previously unaffected by aircraft noise. Further reinforcing the concern is the new multi-rotor designs, which introduce additional sources of noise. Research on novel designs provides a limited understanding of the primary noise-generating mechanisms contributing to overall sound production. Among these innovative designs, complex geometries like open Contra-Rotating Propellers (CRP) and Shrouded Contra-Rotating Propellers (S-CRP) emerge. This study focuses on CRPs because they are anticipated to offer increased thrust with the same platform area, crucial for urban UAM operations. Additionally, shrouds are explored for their potential for increased thrust, acoustic shielding, and directivity manipulation, while also offering space for acoustic liners and increasing safety for ground operators. The objective of this study is to isolate the aerodynamic and acoustic installation effects and identify the noise-generating mechanisms of the CRP and S-CRP configurations. For this, the aerodynamics and acoustics of six propeller configurations are analyzed, including both the primary CRP and S-CRP geometries and sub-variants thereof. The exploration uses a hybrid numerical methodology, consisting of an aerodynamic flow solver based on the unsteady Reynolds-Averaged Navier-Stokes equations (uRANS) and a Finite Element Method (FEM) acoustic propagation solver. The latter generates acoustic sources from the aerodynamic solution using the source mode formalism. This not only facilitates an aerodynamic understanding of the acoustic sources but can also detail near-field effects on acoustic propagation. While alternative methodologies achieving similar results necessitate high-fidelity simulations, the uRANS-F, Aerospace Engineering | Flight Performance and Propulsion

We conducted an analysis of the process of GW breaking from an energy perspective using the output from a high-resolution compressible atmospheric model. The investigation focused on the energy conversion and transfer that occur during the GW breaking. The total change in kinetic energy and the amount of energy converted to internal energy and potential energy within a selected region were calculated. Prior to GW breaking, part of the potential energy is converted into kinetic energy, most of which is transported out of the chosen region. After the GW breaks and turbulence develops, part of the potential energy is converted into kinetic energy, most of which is converted into internal energy. The calculations for the transfer of kinetic energy among GWs, turbulence, and the BG in a selected region, as well as the contributions from various interactions (BG-GW, BG-turbulence, and GW-turbulence), are performed. At the point where the GW breaks, turbulence is generated. As the GW breaking process proceeds, the GWs lose energy to the background. At the start of the GW breaking, turbulence receives energy through interactions between GWs and turbulence, and between the BG and turbulence. Once the turbulence has accumulated enough energy, it begins to absorb energy from the background while losing energy to the GWs. The probabilities of instability are calculated during various stages of the GW-breaking process. The simulation suggests that the propagation of GWs results in instabilities, which are responsible for the GW breaking. As turbulence grows, it reduces convective instability.

In this paper, we discuss our novel approach to support mixed-direction shunting in the planning domain for tree-like shunting yards. We explain how we used numeric fluents to improve an existing PDDL domain to support such actions. We elaborate on the underlying conceptual model of our domain and argue how does it accurately represent shunting problems. Furthermore, we describe the experiment that we performed with the MetricFF planner to evaluate our domain and discuss the results of the experiment. Finally, we argue why the MetricFF planning system is not suitable to efficiently support our domain in real-life scenarios., CSE3000 Research Project, Computer Science and Engineering

Over recent years, significant advances have been made in the modelling of the impact dynamics between debris flows and single and dual rigid and flexible barriers. Numerical tools and analytical formulations have been proposed to predict the impact force, runup height, barrier deformation, and overflow and landing dynamics. However, there remains a dearth of well-recognised tools that can be used in routine engineering design practice because their reliability is unclear. On 8 and 9 May 2022, a virtual Class A Prediction Symposium on Debris Flow Impact Forces on Single and Dual Barriers was held to evaluate the reliability of existing design tools and identify areas for improvement to advance the current state of barrier design. The symposium was organised by The Hong Kong University of Science and Technology, Norwegian University of Science and Technology, Institute of Mountain Hazards and Environment of the Chinese Academy of Sciences, and the Geotechnical Engineering Office of the Civil Engineering and Development Department of the HKSAR Government. This paper summarises the existing research on flow-barrier interaction, and details of the symposium, including the prediction cases and results, roundtable discussion, and future research directions. © 2023 The Hong Kong Institution of Engineers.

Nonmetallic Glass Fiber-Reinforced Polymer (GFRP) reinforcing bars are considered a viable alternative to the conventional steel reinforcement because of their high strength-to-weight ratio and noncorrosive nature. This research aimed to investigate the nonlinear structural behavior of GFRP-reinforced concrete beams with discontinuity regions (D-regions) through numerical analysis. Three-dimensional (3D) numerical models were developed to simulate the nonlinear structural behavior of GFRP-reinforced deep beams with and without web openings. The models adopted realistic constitutive laws that accounted for the nonlinear behavior of the materials used. Predictions of the numerical models were validated against published experimental data. A parametric study was conducted to examine the effect of key variables on the structural behavior of GFRP-reinforced deep beams with and without web openings. The interaction between the concrete compressive strength (fc’), shear span-to-depth ratio (a/h), size and location of the web opening was elucidated. Simplified analytical formulas capable of predicting the shear capacity of GFRP-reinforced beams with D-regions were introduced based on an inverse analysis of results of the numerical simulation models. Predictions of the proposed analytical formulas were in good agreement with the results of the simulation models.

Optimal control is a paradigm for solving optimization problems involving dynamical systems, which are to be controlled. It is able to solve fish harvesting problems, in which we want to optimize harvesting out-take by considering fishing as a control function that acts on the state of the dynamical system, which represents the growth of fish species in the environment. Other modelling aspects of optimal control are defining terminal costs and running costs, e.g. maximizing profit. We keep the terminal condition comparable for a different number of species. It is based on the initial population. By using the optimal control Hamiltonian and Pontryagin’s Maximum Principle we can calculate the optimal state trajectories corresponding to suitable optimal controls. The Hamiltonian is dependent on the state equation and the running costs. We present two approaches of modelling the running costs. An approach that is not directly translatable to the fish harvesting problem, but it leads to a smooth Hamiltonian, which greatly simplifies derivation and computation. The other, which is equivalent to maximizing profit, leads to a non-smooth Hamiltonian. This leads to jump-discontinuous derivatives needed for computation. We propose to regularize the derivatives of the Hamiltonian using suitable smooth functions, such that it is equivalent to regularizing the Hamiltonian directly. We give details for implementing both approaches up to systems of n competing species. After which we go into detail on algorithms and programming structure implemented. Finally, in modest numerical experiments, for one and two species, we show the relation between the optimal control and the terminal costs. But more interestingly, that the smooth Hamiltonian models are inadequate and regularized Hamiltonian models are the preferred choice. Intriguingly, the latter approach results in steady state solution, wherethe control acts as a stabilizer., Optimal kontroll är ett paradigm för att lösa optimeringsproblem som omfattar dynamiska system som ska kontrolleras. Den kan lösa problem med skörd av fisk där vi vill optimera skörd av fisk genom att betrakta fisket som en kontrollfunktion som verkar på tillståndet i det dynamiska systemet, som representerar tillväxten av fiskarter i miljön. Andra modelleringsaspekter av optimal styrning är att definiera slutkostnader och löpande kostnader, t.ex. maximering av vinsten. Vi håller terminalvillkoret jämförbart för ett antal olika arter. Det baseras på den ursprungliga populationen.Genom att använda Hamiltonianen för optimal styrning och Pontryagins maximiprincip kan vi beräkna de optimala tillståndsbanorna som motsvarar lämpliga optimala styrningar. Hamiltonianen är beroende av tillståndsekvationen och driftskostnaderna. Vi presenterar två metoder för att modellera driftskostnaderna. Ett tillvägagångssätt som inte är direkt överförbart till problemet med skörd av fisk, men som leder till en slät Hamiltonian, vilket förenklar härledning och beräkning avsevärt. Den andra metoden, som är likvärdig med vinstmaximering, leder till en icke slät Hamiltonian. Detta leder till hopp-diskontinuerliga derivator som behövs för beräkningen. Vi föreslår att man reglerar Hamiltonianens derivator med hjälp av lämpliga släta funktioner, så att det är likvärdigt med att reglera Hamiltonianen direkt. Vi ger detaljer för genomförandet av bå-da tillvägagångssätten upp till system med n konkurrerande arter. Därefter går vi in i detalj på algoritmer och den implementerade programmeringsstrukturen. Slutligen visar vi genom numeriska experiment, för en och två arter, sambandet mellan den optimala kontrollen och slutkostnaderna. Men mer intressant är att de släta hamiltoniska modellerna är otillräckliga, vilket ger upphov till att reglerade hamiltoniska modeller är att föredra. Intressant nog resulterar det senare tillvägagångssättet i en stabil lösning, där kontrollen fungerar som en stabilisa

[ES] El modelo matemático utilizado en el estudio del oleaje es REEF3D::FNPF, un modelo de resolución en fase (Phase-resolving) basado en la resolución de la equación de Laplace. Para llevar a cabo dicho estudio se han realizado diversas simulaciones. Primero se realizaron dos estudios de convergencia, bidimensional y tridimensional. Una vez establecido el tamaño de celda a usar para una simulación eficiente del oleaje se llevaron a cabo diversas simulaciones para el estudio del oleaje. Estas simulaciones a parte de proporcionar la altura de ola significante, el periodo pico y el espectro de energía en los puntos deseados también nos proporcionó una reconstrucción del oleaje a lo largo del espacio y tiempo. Mediante esta reconstrucción fenómenos como la difracción, refracción y reflexión han sido estudiados conjuntamente con la altura de ola significante, los periodos predominantes y la energía del oleaje (densidad espectral) en el exterior e interior del puerto, especialmente en la zona entre el Muelle de la Energía y el Muelle Prat, donde el nuevo pantalán ha sido proyectado., [EN] The numerical wave model chosen for this thesis is the phase-resolving model REEF3D ::FNPF. Several simulations were carried out to ensure a proper representation of the wave transformation phenomena. Convergence studies were made in order to select an effective and efficient cell size for the numerical domain. After determining the cell size, three simulations were made with different significant wave heights and peak periods to ensure concurrent results. To select the most unfavorable scenario, the maximum annual significant wave height was selected in the most unfavorable direction for the area regarding the new dock, the southeastern incident waves. The analysis of wave conditions at the harbor show that strong wave transformation phenomena take place. Thanks to the visual representation of the wave field these phenomena can be observed and studied. This together with the speed and accuracy obtained in the results, make REEF3D::FNPF a great tool for harbor modeling. The strong diffraction and energy dissipation in the southern entrance of the Barcelona harbor make possible the introduction of a new dock, as they significantly reduce the significant wave height and the spectral energy density.

This thesis presents a computational study of the formation and evolution of Milky-Way-mass galaxies using FIRE-2 cosmological zoom-in simulations. All simulated galaxies experience an early period of bursty star formation that transitions to a late-time steady phase of near-constant star formation. Stars form at different time have very different kinematic properties, morphologies, and chemical abundances. We classify stars in the central galaxy as bulge, thick-disc, and thin-disc according to their orbital properties and discover that these components are assembled in a time-sequence from early to late times, respectively. Stars born during the early bursty phase have more radial orbits and they evolve into a central spheroidal structure at z=0, while stars form during the late-time steady phase have more circular orbits and thin-disc-like morphology. Thick-disc stars form during a transitional period, mostly before the star formation settles down. Thus, we find a strong correlation between the age of thick-disc population at z=0 and the transition time. We also find that galaxies with earlier transition from bursty to steady star formation have higher thin-disc fractions at z=0. Bursty star formation at early time also triggers a significant amount of strong outflow events. During starbursts, the instantaneous fraction of stars born in outflows can be as high as ~ 20 - 50%. These outflow stars contribute substantially to the in-situ stellar halo. Statistically, stellar populations form at different times tend to maintain their disc/bulge-like kinematics, with only moderate evolution over time. Mergers do alter kinematics, but play a secondary role in ''disc-settling'' process. They do not destroy the thin disc nor change broad trend between star formation transition time and thin/thick-disc/bulge properties. If our simulations are representative of the Universe, then stellar archaeological studies of the Milky Way can provide a window into past star-formation mod

The chirality-flow formalism has proven to make amplitude calculations in the Standard Model analytically simple in comparison to previously established formalisms. To test the viability of the chirality-flow formalism for numerical implementations, a Chiral Automized Flow Extension (CAFE) for MadGraph5_aMC@NLO has been developed to compare amplitude evaluation time scaling between the two. CAFE uses a new UFO format model and a new HELAS-like library to make evaluations in the chirality-flow formalism. Additionally, an algorithm has been implemented to make a simple gauge choice, based on which diagrams that will not contribute to the matrix elements will be discarded already at compile time. The effects of these two changes on evaluation time scaling with process complexity have been studied, and CAFE has been shown to both be faster for all considered processes and to scale better with diagram complexity than MadGraph5., Få blir nog förvånade om någon hävdar att beräkningar inom partikelfysik är invecklade. Bara för att beräkna sannolikheten att den enklaste processen vi tar hänsyn till (vilket är när två elektroner krockar och studsar mot varandra) krävs det åtminstone tre-fyra sidor med ren matematik, och svårigheterna växer snabbt ju mer komplexa processer vi arbetar med. För att kunna ha teoretiska värden att jämföra våra experimentella mätningar med måste dessa sannolikheter dock beräknas; utan dem är det omöjligt att säga när vi väl upptäcker fysik bortom våra nuvarande teorier. En av de huvudsakliga orsakerna till problematiken är att den matematik vi använder för att beskriva universum är fyrdimensionell: Vi har tre rumsdimensioner (upp-ned, höger-vänster, framåt-bakåt) och en tidsdimension (framtid-förflutet). Fyrdimensionell matte är mycket krånglingare än den medelpersonen är van vid, då det inte längre räcker att ta hänsyn till hur ett tal relaterar till ett annat: Det räcker inte att säga att 1 + 1 = 2. I fyrdimensionell matte måste det tas hänsyn till hur höger-vänster påverkar upp-ned, hur framåt-bakåt påverkar framtid-förflutet, och vice versa för alla kombinationer mellan dem: Kort och gott måste hur fyra olika saker relaterar till varandra beräknas, vilket blir 4 × 4 = 16 gånger mer komplicerat än vad vanlig endimensionell matte är. Vi måste nu betrakta om ettan vi tittar på ligger längs höger-vänster eller uppåt-nedåt innan vi kan säga om 1 plus 1 är så enkelt som 2, eller om det är en etta åt höger som är helt skild från en etta som riktar bakåt. För att förenkla beräkningarna har fysiker sedan 80-talet arbetat med att beskriva sakerna vi beräknar i lägre-dimensionell matematik. Genom att dela in det fyrdimensionella rummet vi lever i i två stycken tvådimensionella rum som beter sig ungefär likadant förenklades beräkningar med den så kallade spinor-helicitetsformalismen, som har blivit stor de senaste årtiondena. På senare år har en vidareutveckling av spinor-hel

The transverse flute can be studied on many aspects. In this thesis the sound waves that can be generated inside the flute are studied on their shape and frequencies. To achieve this, two mathematical models of the sound waves inside a flute are developed. To develop these models, solutions to the second dimensional wave equation are calculated analytically and numerically. The exact model is found within a rectangular parallelepipid region with homogeneous boundary conditions. By the method of separation of variables the second-dimensional wave equation is solved and a function of the air pressure inside the flute is calculated. This model can be used to visualise the waves inside the flute. It allows approximate true frequencies of measured musical notes in the flute. The second model, the numerical model is found in the same domain as the exact model, but with non-homogeneous boundary conditions.These are more realistic boundary conditions and therefore this model might be more accurate than the exact model. By the method of finite difference the numerical second-dimensional wave equation is solved. A system of two numerical equations is found. One of the equations calculates the pressure of the air inside the flute by inserting the previous pressure and velocity of the wave inside the flute. The other one calculates the velocity of the sound wave inside the flute by inserting the previous pressure of the sound wave inside the flute. The visualisation of this model however is not yet an accurate model to visualise waves inside the transverse flute. Therefore a conclusion is made that the exact model best describes the sound waves that can be generated inside the transverse flute.

RUNKO is a new open-source plasma simulation framework implemented in C++ and PYTHON. It is designed to function as an easy-to-extend general toolbox for simulating astrophysical plasmas with different theoretical and numerical models. Computationally intensive low-level kernels are written in modern C++ taking advantage of polymorphic classes, multiple inheritance, and template metaprogramming. High-level functionality is operated with PYTHON scripts. The hybrid program design ensures good code performance together with ease of use. The framework has a modular object-oriented design that allows the user to easily add new numerical algorithms to the system. The code can be run on various computing platforms ranging from laptops (shared-memory systems) to massively parallel supercomputer architectures (distributed-memory systems). The framework supports heterogeneous multiphysics simulations in which different physical solvers can be combined and run simultaneously. Here, we showcase the framework’s relativistic particle-in-cell (PIC) module by presenting (i) 1D simulations of relativistic Weibel instability, (ii) 2D simulations of relativistic kinetic turbulence in a suddenly stirred magnetically-dominated pair plasma, and (iii) 3D simulations of collisionless shocks in an unmagnetized medium.

To avoid over-designing wave energy converters (WECs), their reliability and survivability aspects need to be accurately addressed. The most common failure modes are: instantaneous failure due to high instantaneous loads, and fatigue failure due to the accumulated damage in the structure during years of operation. Here, we present a fatigue analysis of a point-absorber WEC in sea states corresponding to a 50-year environmental contour from the Dowsing site, UK. The data for this analysis is generated by a WEC-Sim model that is calibrated with a 1:30 scaled WEC from a wave tank experiment. In this study, the partial damage in each 1-hour sea state sample is calculated using the rainflow counting and Palmgren-Miner rule. Then, considering the joint probability density function of the sea states, the equivalent two-million cycle load is 2.42 MN for the full-scale system considering the accumulated damage in 50 years of operation. In a comparison of the fatigue limit state (FLS) and ultimate limit state (ULS), it was found that the ULS is the governing limit state in the design of the WEC system here.

NASA JPL ha dissenyat un nou model numèric determinístic de propagació per carac- teritzar el canal entre un transmissor a la Lluna i un receptor a la Terra. En concret, el transmissor pot ser un rover o una estació base a la superfície i el receptor serà generalment una antena de la Deep Space Network (DSN). El model té en compte les reflexions provo- cades per la superfície lunar i obté la caracterització completa de la propagació del retard i del Doppler, entre d’altres aspectes d’interès com la potència rebuda total de les reflexions, etc. Les entrades del model són la definició de la superfície lunar amb un Digital Elevation Map i de la rugositat del sòl amb els paràmetres del RMS del pendent, entre d’altres. El càlcul de les reflexions multicamí es duu a terme a través d’una discretització del mapa en facetes i amb l’aproximació de rajos de Geometria Òptica. Seguidament, es valida el model en dos passos. El primer, veure l’ajust entre la simplifi- cació teòrica d’un model de dos rajos (raig directe en línia de visió i un únic raig reflectit) modelant la Lluna com una esfera perfecta i llisa. El segon, verificar els resultats del model en un cas real comparant-los amb les dades empíriques disponibles mesurades a través de la DSN i el Lunar Reconaissance Orbiter (LRO). Els resultats obtinguts es mostren en gràfiques comparatives i amb mètriques com ara el progrés de la propagació del Doppler en funció del temps., NASA JPL ha diseñado un nuevo modelo numérico determinístico de propagación para caracterizar el canal entre un transmisor en la Luna y un receptor en la Tierra. En concreto, el transmisor puede ser un rover o una estación base en la superficie y el receptor será generalmente una antena de la Deep Space Network. El modelo contempla las reflexiones provocadas por la superficie lunar y obtiene la caracterización completa de la propagación del retraso y del Doppler, entre otros aspectos de interés como la potencia recibida total de las reflexiones, etc. Las entradas del modelo son la definición de la superficie lunar con un Digital Elevation Map y de la rugosidad del suelo con los parámetros del RMS de la pendiente, entre otros. El cálculo de las reflexiones multicamino se realiza a través de una discretización del mapa en facetas y con la aproximación de rayos de Geometría Óptica. Seguidamente, se valida el modelo en dos pasos. El primero, ver el ajuste entre la simplificación teórica de un modelo de dos rayos (rayo directo en línea de visión y un único rayo reflejado) modelando la Luna como una esfera perfecta y lisa. El segundo, verificar los resultados del modelo en un caso real comparándolos con los datos empíricos disponibles medidos a través de la DSN i el Lunar Reconaissance Orbiter (LRO) Los resultados obtenidos se muestran en gráficas comparativas y con métricas como el progreso de la propagación del Doppler en función del tiempo., NASA JPL designed a new deterministic numerical propagation model to characterize the channel between a transmitter on the Moon and a receiver on Earth. Specifically, the transmitter may be a rover or a surface base station, and the receiver will generally be a Deep Space Network (DSN) antenna. The model takes into account the reflections caused by the lunar limb and obtains the complete characterization of the delay and Doppler spread, among other aspects of interest such as the total received power of the reflections, etc. The model inputs are the definition of the lunar surface with a Digital Elevation Map, and the roughness of the ground specified using parameter such as the slope Root Mean Square, among others. The calculation of the multipath reflections is carried out through a discretization of the map in facets and using the Geometric Optics approximation. The model is validated in two steps. First, it is compared the fit between the theoretical simplification of a two-ray model (direct ray in line of sight and a single reflected ray) assuming the Moon is a perfect, smooth sphere. Second, the results of the model are verified in a real case by comparing them with the available empirical data measured using the DSN and the Lunar Reconaissance Orbiter (LRO). The results obtained are shown in comparative graphs and with metrics such as the evolution of the Doppler spread as a function of time.

The accuracy of theoretical predictions and analyses of diffusion-controlled phase transformations in materials is significantly influenced by the concentration-dependent interdiffusion coefficient (D(C)). It is generally assumed in the literature that the dependence of the interdiffusion coefficient on concentration is isothermally constant. However, this may not be the case because of the evolution of diffusion stresses and strains, which result from factors that can change the concentration gradients at the same solute concentration. This work aims to theoretically and experimentally study how factors that change concentration gradient and, by implication, the diffusion-induced stress/strain (DIS) influence the solute concentration dependence of the interdiffusion coefficient. In this research work, six factors that are postulated to influence the D(C) have been theoretically studied, and the results are experimentally validated using diffusion couples. The six factors studied are time, temperature, non-uniform initial solute distribution, time-varying surface concentration (SC), solute source concentrations, and diffusion geometry. A theoretical model based on DIS and its relaxation is used to simulate concentration profiles and calculate the D(C). Key theoretical predictions are experimentally verified using a newly developed and validated numerical model to reliably extract the D(C) from experimental data. The theoretical and experimental data analyses show that the concentration dependence of interdiffusion coefficient can significantly change when any of the six factors changes. This study shows that the common practice of using a single interdiffusion coefficient to predict isothermal diffusion effects can become significantly unreliable when the dependence of diffusivity on concentration changes. Neglecting the fundamental concept elucidated in this study can lead to the consequential misidentification of the mechanism of microstructural changes through ph

A full understanding of the interaction mechanisms among flow-like landslides and impacted protection structures is still an open issue. Although several approaches, from experimental to numerical, have been used so far, a thoroughly assessment of the hydromechanical behaviour of the landslide body is achievable only through a multiphase and large deformation approach. This paper firstly proposes a conceptual model for a specific type of protection structure, namely a Deformable Geosynthetics-Reinforced Barrier (DGRB), i.e., an embankment made of coarse-grained soil layers reinforced by geogrids. In such a case, the sliding of the barrier along its base, under the impulsive action of a flow-type landslide, is an important landslide energy dissipation mechanism, and a key issue for the design. Then, two different approaches are proposed: i) an advanced hydro-mechanical numerical model based on Material Point Method is tested in simulating the whole complex landslide-structure interaction mechanisms, ii) an analytical model is set up to deal with the landslide energy dissipation and the kinematics of both the landslide and barrier. The calibration of the proposed analytical model is pursued based on the numerical results. Finally, the analytical model is successfully validated to interpret a large dataset of landslide impact field evidence, for whose interpretation also five empirical methods available in the literature are tested., Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., Dynamics of Structures

The study aimed at the phenotypic characterization of a number of species of real ants, Hymenoptera: formicidae, in some governorates of central and northern Iraq, as well as revealing similarities and genetic differences depending on the phenotypic characteristics of 16 samples of real ants. The samples were collected from the governorates (Salah al-Din, Kirkuk, Sulaymaniyah, Erbil) using Collection kit, ants samples were diagnosed in the Research Center and Natural History Museum \ University of Baghdad, and the study was conducted in the laboratories of the College of Science \ University of Tikrit in the period 12/15/2021 – 5/1/2022. Samples were collected and preserved according to the methods used in preserving insects. A phenotypic study was conducted for (38) phenotypic characteristics of the general shape of the head, thorax, abdomen, legs and wings in detail using a anatomical microscope. Temporary sections were photographed using a digital camera and kept until the results are studied. Numerical classification and phenotypic genetic dimension were conducted based on the results of the studied phenotypic traits. The results showed a clear discrepancy between the species, it was shown from the results of the statistical analysis of the values of the phenotypic genetic dimension, which ranged between (0.230-0.958), where the least genetic dimension was between sample No. 1 (Camponotint xerxes Erbil 1) and No. 8 (Camponotint xerxes Kirkuk 2), as it reached 0.230, and that is It is the highest percentage of similarity between the two samples within the studied species. As for the highest genetic dimension, it was 0.958 between sample 14 (Camponotint xerxes Salah al-Din 1) and samples No. 9 and 10 (9-Messor sp Kirkuk, 10- Messor sp Sulaymaniyah 1). There is no match in the traits studied between these two samples, while the values of the genetic dimension for the rest of the species ranged between those values.

We explore the growth of planetary embryos by planetesimal accretion up to and beyond the point at which pebble accretion becomes efficient at the so-called Hill-transition mass. Both the transition mass and the characteristic mass of planetesimals that formed by the streaming instability increase with increasing distance from the star. We developed a model for the growth of a large planetesimal (embryo) embedded in a population of smaller planetesimals formed in a filament by the streaming instability. The model includes in a self-consistent way the collisional mass growth of the embryo, the fragmentation of the planetesimals, the velocity evolution of all involved bodies, and the viscous spreading of the filament. We find that the embryo accretes all available material in the filament during the lifetime of the protoplanetary disc only in the inner regions of the disc. In contrast, we find little or no growth in the outer parts of the disc beyond 5-10 AU. Overall, our results demonstrate very long timescales for collisional growth of planetesimals in the regions of the protoplanetary disc in which giant planets form. This means that in order to form giant planets in cold orbits, pebble accretion must act directly on the largest bodies present in the initial mass function of planetesimals with little or no help from mutual collisions.

[EN] Induced damage during biocomposites drilling is significantly different to that produced on composites based on synthetic reinforcement such as carbon or glass fibers. In composites reinforced with carbon or glass fibers, induced damage increases with feed rate, however damage was observed to decrease with feed rate in biocomposites reinforced with natural fibers. This work is focused on the explanation of this differences between biocomposites and traditional composites based on the effect of strain rate on the material behavior during machining. A FEM model has been developed in ABAQUS/Explicit to verify this hypothesis. This numerical model has been used to explain the differences found between traditional composites and biocomposites in the influence of the main drilling parameters on induced damage during drilling. Experimental tests were conducted to validate the model through the comparison between thrust forces and damage factor for two different drills geometries on Flax/PLA bio composites. The results indicate that the decrease of induced damage with feed rate is only predicted when the constitutive model accounts for experimental behavior observed in this type of composites. Additionally, the numerical model demonstrated the ability to reproduce the effect of the different cutting conditions (cutting speed, feed, thickness and drill geometry) observed during experimental tests on induced damage during drilling.

We explore the orbital dynamics of systems consisting of three planets, each as massive as the Earth, on coplanar, initially circular, orbits about a star of one solar mass. The initial semimajor axes of the planets are equally spaced in terms of their mutual Hill radius, which is equivalent to a geometric progression of orbital periods for small planets of equal mass. Our simulations explore a wide range of spacings of the planets, and were integrated for virtual times of up to 10 billion years or until the orbits of any pair of planets crossed. We find the same general trend of system lifetimes increasing exponentially with separation between orbits seen by previous studies of systems of three or more planets. One focus of this paper is to go beyond the rough trends found by previous numerical studies and quantitatively explore the nature of the scatter in lifetimes and the destabilizing effects of mean motion resonances. In contrast to previous results for five-planet systems, a nontrivial fraction of three-planet systems survive at least several orders of magnitude longer than most other systems with similar initial separation between orbits, with some surviving 1010 years at much smaller orbital separations than any found for five-planet systems. Substantial shifts in the initial planetary longitudes cause a scatter of roughly a factor of two in system lifetime, whereas the shift of one planet's initial position by 100 m along its orbit results in smaller changes in the logarithm of the time to orbit crossing, especially for systems with short lifetimes.

Students in the first Uzbek language of instruction classes experience considerable difficulty in combining numerical with name nouns, due to the interfering influence of the mother tongue. The paper presents material on the use of the text of local history in organizing work on numerical numbers.

In the modern era, fractional order differential equations have gained a significant amount of research work due to their wide range of applications in various branches of science and engineering such as physics, electrical networks, fluid mechanics, control theory, theory of Viscoelasticity, neurology, and theory of electromagnetic acoustics.The spline approximation techniques have been applied extensively for numerical solution of ODEs and PDEs. The spline functions have a variety of significant gains over finite difference schemes. These functions provide a continuous differentiable estimation to solution over the whole spatial domain with great accuracy. The straightforward employment of spline functions provides a solid ground for applying them in the context of numerical approximations for initial/boundary problems.

The Marchenko multiple elimination (MME) and transmission compensation schemes retrieve primary reflections in the two-way traveltime domain without model information or using adaptive subtraction. Both schemes are derived from projected Marchenko equations and are similar to each other, but they use different time-domain truncation operators. The MME scheme retrieves a new data set without internal multiple reflections. The transmission-compensated Marchenko multiple elimination scheme does the same and additionally compensates for transmission losses in the primary reflections. Both schemes can be solved with an iterative algorithm based on a Neumann series. At each iteration, a convolution or correlation between the projected focusing function and the measured reflection response is performed, and, after each convolution or correlation, a truncation in the time domain is applied. After convergence, the resulting projected focusing function is used for retrieving the transmission-compensated primary reflections and the projected Green's function is used for the physical primary reflections. We have determined that internal multiples are removed by using time-windowed input data that only contain primary reflections. We evaluate both schemes in detail and develop an iterative implementation that reproduces the presented numerical examples. The software is part of our open-source suite of programs and fits into the Seismic Unix software suite of the Colorado School of Mines., Applied Geophysics and Petrophysics, ImPhys/Medical Imaging

This thesis aims to provide more insight into the crashworthiness behaviour of a composite aircraft fuselage. This is achieved by studying both analytically and numerically the crushing behaviour of composite energy absorbers. The analytical model, which is based on energy dissipation rates, generalises previously derived analytical models to study a wider variety of structural components. It is found that the analytical model can give an estimation of the mean crushing load of square, C-shaped, and corrugated specimens. Next to the analytical study, numerical models are created to gain insight into the behaviour of the studied shapes when subjected to crash loading. Another part of the numerical study investigates the effectiveness of different material models to capture the complex failure mechanism of the composite crash absorber. In LS-Dyna, the MAT054, MAT058, and MAR262 material models are used, which are all able to reproduce the results obtained from reference tests. The ability of the material models to recreate the crushing phenomenon is thought to originate from the opportunity LS-Dyna offers to degrade material properties in the crush frond, which incorporates the formation of cracks and delaminations. In the final stage of this research, a case study is performed, where different absorbers are introduced into a simplified digital twin of the Next Generation Multifunctional Fuselage Demonstration as developed by the STUNNING project. Here, it is found that the fuselage's energy absorption can be increased by introducing energy absorbers. All the simulated fuselage sections show similar behaviour in the first crash stages, characterised by the flattening of the lower section of the frame. Subsequently, the behaviour of the absorber and the surrounding structure highly depends on the absorber's integration. Finally, it is found that by combining the numerical results of a baseline fuselage section and the analytical model for the energy absorbers, one can, Aerospace Engineering

The process in which a smooth laminar flow transits to a chaotic to a chaotic, turbulent state, is a topic of particular interest in the sectors of energy technology and aerodynamics. To study the different paths that can be followed during the transition process, various tools and methods have been developed. A preliminary investigation of the response of a laminar flow to an internal or external disturbance can be performed by applying Linear Stability Theory principles. In the recent years, the Direct Numerical Simulations of flows offer a more insightful method to study the transition process, since the flow fields are numerically solved using high computational power. Previous research has primarily focused on the stability and transition of Ideal Gas flows, with little attention to the effects of a highly Non-Ideal behaviour. The present work aims to develop a DNS code that can be used to investigate the stability of compressible boundary layers in the vicinity of theWidom Line. For the initialization of a DNS, a two dimensional base flow profile is required. For the calculation of the base flow, a self-similar solution is obtained, using a MATLAB script that has been developed for the purpose of this study. The DNS code is developed in FORTRAN. An inviscid characteristic wave analysis is utilized for the implementation of the boundary conditions, along with numerical sponges to avoid reflections. To trigger the instabilities, periodic suction and blowing is incorporated. For the simulations of non-ideal fluids, a thermodynamic table interpolation tool is incorporated. For the validation of the results obtained by the DNS code, an in-house MATLAB script is used to for the calculation of the growth rate and fluctuation amplitude profiles using LST. Initially, the FORTRAN code is used on ideal-gas simulations, to investigate how different computational parameters will affect the flow field. The parameters are related to mesh resolution, boundary conditions and n

Debris thermal conductivity is a critical parameter in calculating a glacier’s sub- debris ice melt. The method widely used in publications to calculate the apparent thermal conductivity of supraglacial debris layers is based on an estimate of volumet- ric heat capacity of the debris and simple heat diffusion principles. It is presented in Conway and Rasmussen (2000). The analysis of heat diffusion requires a vertical array of temperature measurements through the supraglacial debris cover. This study explores the effect of the temporal and spatial sampling interval and other error sources on the thermal diffusivity values derived using this method. Results show that temporal and spatial truncation errors all underestimate values of thermal diffusivity with increasing sampling intervals. Also, the thermistor precision, the diurnal temperature cycle, and vertical thermistor displacement result in systematic errors. Therefore great care must be taken when performing and analyzing the debris layer measurements to produce reliable results. This problem especially becomes apparent because only a fraction of the available datasets are suitable for determining reliable thermal diffusivity values. Therefore, in this work, an online web application was developed to help other scientists investigate the effect of the sampling interval on their calculated sub-debris ice melt and better plan future measurement campaigns. This study falls under the remit of the IACS working group on debris-covered glaciers and is supported by data provided from within this group., Calvin Beck, Masterarbeit Universität Innsbruck 2021