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Identity statuses in upper-division physics students
https://cds.cern.ch/record/2020573
We use the theories of identity statuses and communities of practice to describe three different case studies of students finding their paths through undergraduate physics and developing a physics subject-specific identity. Each case study demonstrates a unique path that reinforces the link between the theories of communities of practice and identity statuses. The case studies also illustrate how students progress and regress in their commitment to their subject-specific identities and their professional identities. The progression/regression is dependent on their willingness to explore different aspects of a physics professional identity and their availability to carry out such exploration. Identity status and future identity crises can manifest in students' behavior in the classroom. Allowing students to engage in more legitimate practices of the physics community, especially in the form of undergraduate research, helps students to explore their opportunities and inform the level of commitment they wish to make to physics.Irving, Paul WSayre, Eleanor CSat, 30 May 2015 07:44:33 GMT28 May 2015arXiv:1505.07801https://cds.cern.ch/record/2020573Efficient monitoring of blood-stage infection in a malaria rodent model by the rotating-crystal magneto-optical method
https://cds.cern.ch/record/2020572
Global research efforts have been focused on the simultaneous improvement of the efficiency and sensitivity of malaria diagnosis in resource-limited settings and for the active case detection of asymptomatic infections. A recently developed magneto-optical (MO) method allows the high-sensitivity detection of malaria pigment (hemozoin) crystals in blood via their magnetically induced rotational motion. The evaluation of the method using synthetic $\beta$-hematin crystals and P. falciparum in vitro cultures implies its potential for in-field diagnosis. Here, we study the performance of the method in monitoring the in vivo onset and progression of the blood stage infection using a malaria mouse model. We found that the MO method can detect the first generation of intraerythrocytic parasites at the ring stage 61-66 hours after sporozoite injection demonstrating better sensitivity than light microscopy and flow cytometry. MO measurements performed after treatment of severe P. berghei infections show that the clearance period of hemozoin in mice is approx. 5 days which indicates the feasibility of the detection of later reinfections as well. Being label and reagent-free, cost-effective and rapid, together with the demonstrated sensitivity, we believe that the MO method is a suitable candidate for in-depth clinical evaluation in endemic settings.Orban, AgnesRebelo, MariaAlbuquerque, Inês SButykai, AdamKezsmarki, IstvanHänscheid, ThomasSat, 30 May 2015 07:44:33 GMT28 May 2015arXiv:1505.07792https://cds.cern.ch/record/2020572On Uncertainty Quantification of Lithium-ion Batteries
https://cds.cern.ch/record/2020571
In this work, a stochastic, physics-based model for Lithium-ion batteries (LIBs) is presented in order to study the effects of model uncertainties on the cell capacity, voltage, and concentrations. To this end, the proposed uncertainty quantification (UQ) approach, based on sparse polynomial chaos expansions, relies on a small number of battery simulations. Within this UQ framework, the identification of most important uncertainty sources is achieved by performing a global sensitivity analysis via computing the so-called Sobol' indices. Such information aids in designing more efficient and targeted quality control procedures, which consequently may result in reducing the LIB production cost. An LiC$_6$/LiCoO$_2$ cell with 19 uncertain parameters discharged at 0.25C, 1C and 4C rates is considered to study the performance and accuracy of the proposed UQ approach. The results suggest that, for the considered cell, the battery discharge rate is a key factor affecting not only the performance variability of the cell, but also the determination of most important random inputs.Hadigol, MohammadMaute, KurtDoostan, AlirezaSat, 30 May 2015 07:44:32 GMT28 May 2015arXiv:1505.07776https://cds.cern.ch/record/2020571Fractal Growth on the Surface of a Planet and in Orbit around it
https://cds.cern.ch/record/2020570
Fractals are defined as geometric shapes that exhibit symmetry of scale. This simply implies that fractal is a shape that it would still look the same even if somebody could zoom in on one of its parts an infinite number of times. This property is also called self-similarity with several applications including nano pharmacology and drug nano carriers. We are interested in the study of the properties of fractal aggregates in a microgravity environment above an orbiting spacecraft. To model the effect we use a complete expression for the gravitational acceleration. In particular on the surface of the Earth the acceleration is corrected for the effect of oblateness and rotation. In the gravitational acceleration the effect of oblateness can be modeled with the inclusion of a term that contains the J2 harmonic coefficient, as well as a term that depends on the square of angular velocity of the Earth. In orbit the acceleration of gravity at the point of the spacecraft is a function of the orbital elements and includes only in our case the J2 harmonic since no coriolis force is felt by the spacecraft. Using the fitting parameter d = 3.0 we have found that the aggregate monomer number N is not significantly affected and exhibits a minute 0.0001% difference between the geocentric and areocentric latitudes of 90 degrees and 0 degrees. Finally for circular and elliptical orbits around Earth and Mars of various inclinations and eccentricities the aggregate monomer number is not affected at all at the orbital altitude of 300 km.Haranas, IoannisGkigkitzis, IoannisAlexiou, AthanasiosSat, 30 May 2015 07:44:32 GMT31 Oct 2014arXiv:1505.07769https://cds.cern.ch/record/2020570Multifractal detrended moving average analysis of global temperature records
https://cds.cern.ch/record/2020569
Long-range correlation and multifractal nature of the global monthly mean temperature anomaly time series over the period 1850-2012 are studied in terms of the multifractal detrended moving average (MFDMA) method. We try to address the source(s) of multifractality in the time series by comparing the results derived from the actual series with those from a set of shuffled and surrogate series. It is seen that the newly developed MFDMA method predicts a multifractal structure of the temperature anomaly time series that is more or less similar to that observed by other multifractal methods. In our analysis the major contribution of multifractality in the temperature records is found to be stemmed from long-range temporal correlation among the measurements, however the contribution of fat-tail distribution function of the records is not negligible. The results of the MFDMA analysis, which are found to depend upon the location of the detrending window, tend towards the observations of the multifractal detrended fluctuation analysis (MFDFA), if the detrending window is chosen in such a way that 70% of it is covered by the forward (future) records and 30% by the backward (past) with respect to the record (measurement) to be detrended.Mali, ProvashSat, 30 May 2015 07:44:32 GMT17 May 2015arXiv:1505.07748https://cds.cern.ch/record/2020569Seepage flow-stability analysis of the riverbank of Saigon river due to river water level fluctuation
https://cds.cern.ch/record/2020568
The Saigon River, which flows through the center of Ho Chi Minh City, is of critical importance for the development of the city as forms as the main water supply and drainage channel for the city. In recent years, riverbank erosion and failures have become more frequent along the Saigon River, causing flooding and damage to infrastructures near the river. A field investigation and numerical study has been undertaken by our research group to identify factors affecting the riverbank failure. In this paper, field investigation results obtained from multiple investigation points on the Saigon River are presented, followed by a comprehensive coupled finite element analysis of riverbank stability when subjected to river water level fluctuations. The river water level fluctuation has been identified as one of the main factors affecting the riverbank failure, i.e. removal of the balancing hydraulic forces acting on the riverbank during water drawdown.Oya, ABui, H HHiraoka, NFujimoto, MFukagawa, RSat, 30 May 2015 07:44:32 GMT25 May 2015arXiv:1505.07747https://cds.cern.ch/record/2020568Probabilistic Constraint Programming for Parameters Optimisation of Generative Models
https://cds.cern.ch/record/2020567
Complex networks theory has commonly been used for modelling and understanding the interactions taking place between the elements composing complex systems. More recently, the use of generative models has gained momentum, as they allow identifying which forces and mechanisms are responsible for the appearance of given structural properties. In spite of this interest, several problems remain open, one of the most important being the design of robust mechanisms for finding the optimal parameters of a generative model, given a set of real networks. In this contribution, we address this problem by means of Probabilistic Constraint Programming. By using as an example the reconstruction of networks representing brain dynamics, we show how this approach is superior to other solutions, in that it allows a better characterisation of the parameters space, while requiring a significantly lower computational cost.Zanin, MassimilianoCorreia, MarcoSousa, Pedro A CCruz, JorgeSat, 30 May 2015 07:44:32 GMT28 May 2015arXiv:1505.07744https://cds.cern.ch/record/2020567Imaging Microwave and DC Magnetic Fields in a Vapor-Cell Rb Atomic Clock
https://cds.cern.ch/record/2020566
We report on the experimental measurement of the DC and microwave magnetic field distributions inside a recently-developed compact magnetron-type microwave cavity, mounted inside the physics package of a high-performance vapor-cell atomic frequency standard. Images of the microwave field distribution with sub-100 $\mu$m lateral spatial resolution are obtained by pulsed optical-microwave Rabi measurements, using the Rb atoms inside the cell as field probes and detecting with a CCD camera. Asymmetries observed in the microwave field images can be attributed to the precise practical realization of the cavity and the Rb vapor cell. Similar spatially-resolved images of the DC magnetic field distribution are obtained by Ramsey-type measurements. The T2 relaxation time in the Rb vapor cell is found to be position dependent, and correlates with the gradient of the DC magnetic field. The presented method is highly useful for experimental in-situ characterization of DC magnetic fields and resonant microwave structures, for atomic clocks or other atom-based sensors and instrumentation.Affolderbach, ChristophDu, Guan-XiangBandi, ThejeshHorsley, AndrewTreutlein, PhilippMileti, GaetanoSat, 30 May 2015 07:44:32 GMT28 May 2015arXiv:1505.07739https://cds.cern.ch/record/2020566Dirac Phase interferometer in a plasmonic waveguide
https://cds.cern.ch/record/2020565
By viewing plasmon waves in metallic waveguides as propagating electric and magnetic dipoles we show that according to laws of quantum mechanics they will acquire additional phase when propagating through space with static magnetic field. The new effect is physically different from conventional magneto-plasmonic phenomena and is sufficiently strong to observe it under routinely accessible experimental conditions.Savinov, VZheludev, N ISat, 30 May 2015 07:44:32 GMT28 May 2015arXiv:1505.07735https://cds.cern.ch/record/2020565Non-Euclidean ideal spectrometer
https://cds.cern.ch/record/2020564
We describe the mathematical scheme for an anomaly-free ideal spectrometer, based on a 2-dimensional plane medium with conical regions of bounded slope. Moreover, the construction may be realised in many different configurations.Earp, Henrique N SáKyotoku, Bernardo de Barros CorreiaSicca, VladmirSat, 30 May 2015 07:44:32 GMT27 May 2015arXiv:1505.07730https://cds.cern.ch/record/2020564Vorticity evolution in a rigid pipe of circular cross-section
https://cds.cern.ch/record/2020563
In this paper, we show that the spatio-temporal evolution of incompressible flows in a long circular pipe can be described by vorticity dynamics. The principal techniques to obtain solution are similar to those used for flows in the whole space. As the consideration of the Navier-Stokes equations is given in a cylindrical co-ordinates, two aspects of complication arise. One is the interaction of the velocity components in the radial and azimuthal directions due to the fictitious centrifugal force in the equations of motion. The rate of the vorticity production at pipe wall depends on the initial data at entry and hence is unknown a priori; it must be determined as part of the solution. The vorticity solution obtained defines an intricate flow field of multitudinous degrees of freedom. As the Reynolds number increases, the analytical solution predicts vorticity-scale proliferations in succession. For sufficient large initial data, pipe flows are of turbulent nature. The solution of the governing equations is globally regular and does not bifurcate in space or in time. It is asserted that laminar-turbulent transition is a dynamic process inbred in the non-linearity. The presence of exogenous disturbances, due to imperfect test environments or purpose-made artificial forcing, distorts the course of the intrinsic transition. The flow structures observed by Reynolds (1883) and others can be synthesised and elucidated in light of the current theory.Lam, FSat, 30 May 2015 07:44:32 GMT28 May 2015arXiv:1505.07723https://cds.cern.ch/record/2020563Surpassing the Path-Limited Resolution of a Fourier Transform Spectrometer with Frequency Combs
https://cds.cern.ch/record/2020562
Fourier transform spectroscopy based on incoherent light sources is a well-established tool in research fields from molecular spectroscopy and atmospheric monitoring to material science and biophysics. It provides broadband molecular spectra and information about the molecular structure and composition of absorptive media. However, the spectral resolution is fundamentally limited by the maximum delay range ({\Delta}$_{max}$) of the interferometer, so acquisition of high-resolution spectra implies long measurement times and large instrument size. We overcome this limit by combining the Fourier transform spectrometer with an optical frequency comb and measuring the intensities of individual comb lines by precisely matching the {\Delta}$_{max}$ to the comb line spacing. This allows measurements of absorption lines narrower than the nominal (optical path-limited) resolution without ringing effects from the instrumental lineshape and reduces the acquisition time and interferometer length by orders of magnitude.Maslowski, PiotrLee, Kevin FJohansson, Alexandra CKhodabakhsh, AmirKowzan, GrzegorzRutkowski, LucileMills, Andrew AMohr, ChristianJiang, JieFermann, Martin EFoltynowicz, AleksandraSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07706https://cds.cern.ch/record/2020562Damping factors for head-tail modes at strong space charge
https://cds.cern.ch/record/2020561
This paper suggests how feedback and Landau damping can be taken into account for transverse oscillations of bunched beam at strong space charge.Burov, AlexeySat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07704https://cds.cern.ch/record/2020561Lorenz-Mie theory for 2D scattering and resonance calculations
https://cds.cern.ch/record/2020560
This PhD tutorial is concerned with a description of the two-dimensional generalized Lorenz-Mie theory (2D-GLMT), a well-established numerical method used to compute the interaction of light with arrays of cylindrical scatterers. This theory is based on the method of separation of variables and the application of an addition theorem for cylindrical functions. The purpose of this tutorial is to assemble the practical tools necessary to implement the 2D-GLMT method for the computation of scattering by passive scatterers or of resonances in optically active media. The first part contains a derivation of the vector and scalar Helmholtz equations for 2D geometries, starting from Maxwell's equations. Optically active media are included in 2D-GLMT using a recent stationary formulation of the Maxwell-Bloch equations called steady-state ab initio laser theory (SALT), which introduces new classes of solutions useful for resonance computations. Following these preliminaries, a detailed description of 2D-GLMT is presented. The emphasis is placed on the derivation of beam-shape coefficients for scattering computations, as well as the computation of resonant modes using a combination of 2D-GLMT and SALT. The final section contains several numerical examples illustrating the full potential of 2D-GLMT for scattering and resonance computations. These examples, drawn from the literature, include the design of integrated polarization filters and the computation of optical modes of photonic crystal cavities and random lasers.Gagnon, DenisDubé, Louis JSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07691https://cds.cern.ch/record/2020560Dispersion for Two Classes of Random Variables: General Theory and Application to Inference of an External Ligand Concentration by a Cell
https://cds.cern.ch/record/2020559
We derive expressions for the dispersion for two classes of random variables in Markov processes. Random variables like current and activity pertain to the first class, which is composed by random variables that change whenever a jump in the stochastic trajectory occurs. The second class corresponds to the time the trajectory spends in a state (or cluster of states). While the expression for the first class follows straightforwardly from known results in the literature, we show that a similar formalism can be used to derive an expression for the second class. As an application, we use this formalism to analyze a cellular two-component network estimating an external ligand concentration. The uncertainty related to this external concentration is calculated by monitoring different random variables related to an internal protein. We show that, inter alia, monitoring the time spent in the phosphorylated state of the protein leads to a finite uncertainty only if there is dissipation, whereas the uncertainty obtained from the activity of the transitions of the internal protein can reach the Berg and Purcell limit even in equilibrium.Barato, Andre CSeifert, UdoSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07652https://cds.cern.ch/record/2020559Interplay between Detection Strategies and Stochastic Resonance Properties
https://cds.cern.ch/record/2020558
We discuss how to exploit stochastic resonance with the methods of statistical theory of decisions. To do so, we evaluate two detection strategies: escape time analysis and strobing. For a standard quartic bistable system with a periodic drive and disturbed by noise, we show that the detection strategies and the physics of the double well are connected, inasmuch as one (the strobing strategy) is based on synchronization, while the other (escape time analysis) is determined by the possibility to accumulate energy in the oscillations. The analysis of the escape times best performs at the frequency of the geometric resonance, while strobing shows a peak of the performances at a special noise level predicted by the stochastic resonance theory. We surmise that the detection properties of the quartic potential are generic for overdamped and underdamped systems, in that the physical nature of resonance decides the competition (in terms of performances) between different detection strategies.Addesso, PaoloPierro, VincenzoFilatrella, GiovanniSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07646https://cds.cern.ch/record/2020558Cumulant expansions for atmospheric flows
https://cds.cern.ch/record/2020557
The equations governing atmospheric flows are nonlinear, and consequently the hierarchy of cumulant equations is not closed. But because atmospheric flows are inhomogeneous and anisotropic, the nonlinearity may manifests itself only weakly through interactions of mean fields with disturbances such as thermals or eddies. In such situations, truncations of the hierarchy of cumulant equations hold promise as a closure strategy. We review how truncations at second order can be used to model and elucidate the dynamics of turbulent atmospheric flows. Two examples are considered. First, we study the growth of a dry convective boundary layer, which is heated from below, leading to turbulent upward energy transport and growth of the boundary layer. We demonstrate that a quasilinear truncation of the equations of motion, in which interactions of disturbances among each other are neglected but interactions with mean fields are taken into account, can successfully capture the growth of the convective boundary layer. Second, we study the evolution of two-dimensional large-scale waves, which are representative of waves seen in Earth's upper atmosphere. We demonstrate that a cumulant expansion truncated at second order (CE2) can capture the evolution of such waves and their nonlinear interaction with the mean flow in some circumstances, for example, when the wave amplitude is small enough or the planetary rotation rate is large enough. However, CE2 fails to capture the flow evolution when nonlinear eddy--eddy interactions in surf zones around critical layers become important. Higher-order closures can capture these missing interactions. The results point to new ways in which the dynamics of turbulent boundary layers may be represented in climate models, and they illustrate different classes of nonlinear processes that can control wave dissipation and momentum fluxes in the troposphere.Ait-Chaalal, FaridSchneider, TapioMeyer, BettinaMarston, J BSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07643https://cds.cern.ch/record/2020557Condensate Nuclei and Magnetic Polarity Reversals in the Sun and Solar-type Stars
https://cds.cern.ch/record/2020556
Magnetic field generation in the Sun and solar-type stars is modeled here based on the formation of magnetically polarized condensates (B. M. Mirza, Mod. Phys. Lett. B 28 (2014) 1450148) under the high density and pressure conditions. The correct orders of magnitude for the time period and the energy loss in a solar cycle are deduced, as well as the enhancement in the energy emission observed during solar cycles. It is shown that this feedback magnetic field along with differential rotation is sufficient to generate the toroidal magnetic field in the solar exterior. The model is useful in determining magnetic polarity reversals, energy generation, and reversal times, in solar-type stars.Mirza, Babur MSat, 30 May 2015 07:44:31 GMT28 May 2015arXiv:1505.07642https://cds.cern.ch/record/2020556Effect of tube diameter and capillary number on platelet margination and near-wall dynamics
https://cds.cern.ch/record/2020555
The effect of tube diameter $D$ and capillary number $Ca$ on platelet margination in blood flow at $\approx 37\%$ tube haematocrit is investigated. The system is modelled as three-dimensional suspension of deformable red blood cells and nearly rigid platelets using a combination of the lattice-Boltzmann, immersed boundary and finite element methods. Results show that margination is facilitated by a non-diffusive radial platelet transport. This effect is important near the edge of the cell-free layer, but it is only observed for $Ca > 0.2$, when red blood cells are tank-treading rather than tumbling. It is also shown that platelet trapping in the cell-free layer is reversible for $Ca \leq 0.2$. Only for the smallest investigated tube ($D = 10 \mu\text{m}$) margination is essentially independent of $Ca$. Once platelets have reached the cell-free layer, they tend to slide rather than tumble. The tumbling rate is essentially independent of $Ca$ but increases with $D$. Tumbling is suppressed by the strong confinement due to the relatively small cell-free layer thickness at $\approx 37\%$ tube haematocrit.Krüger, TimmSat, 30 May 2015 07:44:30 GMT28 May 2015arXiv:1505.07624https://cds.cern.ch/record/2020555Isolation of coherent and incoherent nonlinear spectroscopic signals by phase modulation
https://cds.cern.ch/record/2020554
We investigate the effect of phase modulation of laser beams on the coherent and incoherent non-linear signals arising from the interaction of femtosecond pulses with matter. We observe that two collinear beams, whose phases are modulated by frequencies $\phi_1$ and $\phi_2$, produce two second harmonic signals from non-linear crystals whose intensities at the detector are modulated at the frequencies $\phi_2-\phi_1$ and $2(\phi_2-\phi_1)$. We also observe that an incoherent action signal, such as fluorescence and photocurrent, which arises from the absorption of two photons, is modulated at the same frequencies as in the case of second harmonic generation. We present a theoretical analysis to explain our observations. These results are important to understand how phase modulation techniques can be used to isolate different field-matter interaction pathways in a non-linear process. Because the method uses modulation of the signal intensity rather than wave-vector matching to isolate different signals, it could be useful to perform multi-photon absorption studies on single molecules or nanoparticles.Karki, Khadga JungKringle, LoniMarcus, Andrew HPullerits, TõnuSat, 30 May 2015 07:44:30 GMT28 May 2015arXiv:1505.07617https://cds.cern.ch/record/2020554How water contributes to pressure and cold denaturation of proteins
https://cds.cern.ch/record/2020552
The mechanisms of cold- and pressure-denaturation of proteins are matter of debate and are commonly understood as due to water-mediated interactions. Here we study several cases of proteins, with or without a unique native state, with or without hydrophilic residues, by means of a coarse-grain protein model in explicit solvent. We show, using Monte Carlo simulations, that taking into account how water at the protein interface changes its hydrogen bond properties and its density fluctuations is enough to predict protein stability regions with elliptic shapes in the temperature-pressure plane, consistent with previous theories. Our results clearly identify the different mechanisms with which water participates to denaturation and open the perspective to develop advanced computational design tools for protein engineering.Bianco, ValentinoFranzese, GiancarloSat, 30 May 2015 07:44:30 GMT28 May 2015arXiv:1505.07594https://cds.cern.ch/record/2020552Morphological instability during steady electrodeposition at overlimiting currents
https://cds.cern.ch/record/2020550
We present a linear stability analysis of a planar metal electrode during steady electrodeposition. We extend the previous work of Sundstrom and Bark by accounting for the extended space-charge density, which develops at the cathode once the applied voltage exceeds a few thermal voltages. In accordance with Chazalviel's conjecture, the extended space-charge region is found to greatly affect the morphological stability of the electrode. To supplement the numerical solution of the stability problem, we have derived analytical expressions valid in limit of low and high voltage, respectively.Nielsen, Christoffer PBruus, HenrikSat, 30 May 2015 07:44:30 GMT28 May 2015arXiv:1505.07571https://cds.cern.ch/record/2020550Localized eigenvector of the non-backtracking matrix
https://cds.cern.ch/record/2020549
Emergence of localized eigenvectors can cause a failure of standard spectral method for graph partitioning. The spectral method using the non-backtracking matrix was proposed as a way to overcome this problem. The numerical experiments on several examples of real networks show that, indeed, the non-backtracking matrix does not exhibit localization of eigenvectors. We show that, however, localized eigenvectors of the non-backtracking matrix out of the spectral band can exist, deteriorating the performance of graph partitioning.Kawamoto, TatsuroSat, 30 May 2015 07:44:30 GMT28 May 2015arXiv:1505.07543https://cds.cern.ch/record/2020549Quantitative analysis of intermediately and infinitely thick samples with thin sample approach without sample preparation using confocal X-ray fluorescence
https://cds.cern.ch/record/2020548
In order to validate that the confocal X-ray fluorescence had potential applications in analyzing the intermediately and infinitely thick samples with thin sample approach without sample preparations, as an example, the confocal X-ray fluorescence based on polycapillary X-ray optics was used to analyze multi elements solutions.Sun, Xue-PengLiu, Zhi-GuoSun, Tian-XiPeng, SongSun, Wei-YuanLi, Fang-ZuoJiang, Bo-WenMa, Yong-ZhongDing, Xun-LiangSat, 30 May 2015 07:44:30 GMT27 May 2015arXiv:1505.07530https://cds.cern.ch/record/2020548A Gaussian-Like Immersed Boundary Kernel with Improved Translational Invariance and Smoothness
https://cds.cern.ch/record/2020547
The immersed boundary (IB) method is a general mathematical framework for studying problems involving fluid-structure interactions in which an elastic structure is immersed in a viscous incompressible fluid. In the IB formulation, the fluid described by Eulerian variables is coupled with the immersed structure described by Lagrangian variables via the use of the Dirac delta function. From a numerical standpoint, the Lagrangian force spreading and the Eulerian velocity interpolation are carried out by a regularized, compactly supported discrete delta function or kernel. Immersed-boundary kernels are derived from a certain set of postulates to achieve approximate grid translational invariance, interpolation accuracy and computational efficiency. In this note, we present a new 6-point immersed-boundary kernel that is $\mathcal{C}^3$ and features a substantially improved translational invariance compared to other common IB kernels.Bao, Yuan-XunKaye, JasonPeskin, Charles SSat, 30 May 2015 07:44:30 GMT27 May 2015arXiv:1505.07529https://cds.cern.ch/record/2020547