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In this paper we present systems for dual modality imaging, combining fluorescence-enhanced diffuse optical tomography and X-ray computed tomography. Fluorescence diffuse optical tomography is carried out in a cylindrical geometry, which ensures optimal sampling and a straight forward integration with the X-ray modality. Specific acquisition protocols and reconstruction software have been developed to this end. The X-ray computed tomography serves two purposes. First, it provides the anatomical information in the registered dual modality images. Second, it provides the actual shape and boundaries of the animal as a priori input to the fluorescence reconstruction algorithm. To evaluate the performance of the optical imaging system, experiments have been conducted on phantoms, mice with inserted fluorescing capillaries, and finally on mice bearing tumors, ex-vivo and in-vivo. Experiments on mice with capillaries inserted in different region of interest, allow estimating the detection limits of fluorophore concentrations. The fluorescence reconstructions are shown to be geometrically consistent with the X-ray images. Finally we demonstrate the capability of the bimodal system to localize real tumours in mice in-vivo. These results show that dual modality fluorescence-enhanced diffuse optical tomography and X-ray computed tomography imaging in cylindrical geometry has a high potential for small animal tumour evolution studies., ISRN optics, 2012, ISSN:2090-7826

International audience; The aim of this paper is to investigate the origin of the diameter-dependence of Young’s modulus in hemp fibres. In view of the considerable experimental difficulties encountered when determining the 3D morphology of elementary fibres, the influence of the fibre morphology and size on the E-modulus is studied using a mathematical model. An approach based on the 3D elastic theory is used to construct a model ofthe fibre structure, and to predict its mechanical properties. We clearly show that the modulus is dependent on the size of the lumen and on the outer fibre diameter. This structural effect, induced by the cylindrical geometry, the multi-layered organisation, and the orientation of the cellulose microfibrils only partly explains the large, experimentally determined dispersion of apparent E-modulus, as a function of fibre diameter. Ultrastructural parameters, such as cellulose crystallinity and microfibril angles, are identified to be the main factors involved in this dependence.

This paper uses transient frequency methods to locate a leak in a pipeline system when a leak is modeled as a small cylindrical pipe element open to atmospheric pressure on one end. The impedance of the leak as a small cylindrical pipe is included in the transfer function equation at the closed valve in a reservoir-pipe-valve system. The impedance diagram of this system with cylindrical leak is plotted and analyzed; the influence of the pipe thickness on leak locations is studied. The numerical study relying on impedance method shows that the cylindrical leak geometry approach allows secondary peaks to be detected only for thick pipes. By imposing a periodic pattern on the resonant responses, the leak with cylindrical geometry can be located and its location is based on an empirical relation. The computed results show satisfactory agreement with previous works when leak is modeled by a circular orifice.

A stepwise coupled-mode method using the direct global matrix approach is proposed. This method is capable of handling two-dimensional problems with either a point source in cylindrical geometry or a line source in plane geometry. Using the direct global matrix approach, this method is numerically stable. In addition, by introducing appropriately normalized range solutions, this model is free from the numerical overflow problem. Furthermore, we put forward source conditions appropriate for the line-source problem in plane geometry. As a result, this method is capable of addressing the scenario with a line source on top of a sloping bottom. The numerical simulations indicate that the proposed model is accurate, efficient, and numerically stable. Consequently, this model can serve as a benchmark in range-dependent propagation modeling. Although this method is verified by an ideal wedge problem in this paper, the formulation applies to realistic problems as well.

In this work we investigate by numerical simulation the electrical properties of the junctionless nanowire field-effect transistor, which has recently been proposed as a possible alternative to the junction-based FET. The numerical model assumes a cylindrical geometry and is meant to provide a physical understanding of the device behaviour by highlighting the features of the I–V and C–V characteristics, as well as the electrostatic potential and carrier concentration within the channel. Numerical results are compared with the experimental turn-on characteristics and are found to provide a generally-good agreement. Finally, we discuss the strengths and the limitations of this device as a possible candidate for future technology nodes.

A question which has not been addressed so far in the analysis of the twisting motion of the heart, relates to the existence of any advantages in energetic expenditure due to differential contractile properties across the wall of the ventricles. The question is addressed in this paper by a highly simplified analytical model of the ventricular cavity, based on a cylindrical geometry and set in the context of the linear theory of elasticity; however, the anisotropy of contraction is also taken into account. It is concluded, that when oppositely directed spirals of fibres in the internal and external layers of the cylinder keep the torsion within suitable limits, i.e. mimicking the biological context, a smaller energetic expenditure is related to a transmural pattern of contraction which is not uniform, and presents a larger epicardial contraction.

Radiofrequency (RF) ablation with internally cooled needle-like electrodes is widely used in medical techniques such as tumor ablation. The device consists of a metallic electrode with an internal liquid cooling system that cools the electrode surface. Theoretical modeling is a rapid and inexpensive way of studying different aspects of the RF ablation process by the bioheat equation, and the analytical approach provides an exact solution to the thermal problem. Our aim was to solve analytically the RF ablation transient time problem with a needle-like internally cooled cylindrical electrode while considering the blood perfusion term. The results showed that the maximal tissue temperature is reached 3mm from the electrode, which confirms previous experimental findings. We also observed that the temperature distributions were similar for three coolant temperature values (5 °C, 15 °C, and 25 °C). The differences were only notable in temperature very close to the probe. Finally, considering the 50 °C line as a thermal lesion mark, we found that lesion diameter was around 2cm, which is exactly that observed experimentally in perfused hepatic tissue and slightly smaller than that observed in nonperfused (ex vivo) hepatic tissue. Copyright © 2012 Juan A. Lpez Molina et al., This work received financial support from the Spanish "Plan Nacional de I + D + i del Ministerio de Ciencia e Innovacion" Grant no. TEC2008-01369/TEC. The translation of this paper was funded by the Universitat Politecnica de Valencia, Spain.

We present a new erase saturation issue compromising the performance of cylindrical charge-trap cells integrated along junction-less NAND strings. The phenomenon comes from the inability to properly induce an inversion layer in the inter-cell regions of the string during read in the cylindrical geometry, pinning the threshold voltage (V T ) resulting from cell erase. The dependence of this issue on string parameters is investigated, showing that a reduction in the inter-cell regions may relieve it. However, this originates a trade-off against the constraints raised by the lateral diffusion of electrons in the charge-trap layer during data retention. It is shown that this trade-off can be easily managed by strings with large substrate radius, while its solution is more critical for small radii.

Based on linear potential theory, the general three-dimensional problem of steady supersonic flow inside quasi-cylindrical ducts is formulated as an initial-boundary-value problem for the wave equation, whose general solution arises as an infinite double series of the Fourier–Bessel type. For a broad class of solutions including the general axisymmetric case, it is shown that the presence of a discontinuity in wall slope leads to a periodic singularity pattern associated with non-uniform convergence of the corresponding series solutions, which thus are unsuitable for direct numerical computation. This practical difficulty is overcome by extending a classical analytical method, viz. Kummer's series transformation. A variety of elementary flow fields is presented, whose complex cellular structure can be qualitatively explained by asymptotic laws governing the propagation of small perturbations on characteristic surfaces.

The radial self-similar expansion of negatively charged impurity or dust particles in a cylindrical geometry is investigated using the multi-fluid theory. Three different types of self-similar solutions are considered. Various asymptotic limits of physical interest in the self-similar space are shown to occur.

Wheat breakfast flakes were compacted in a cylindrical geometry using two different techniques and the volume measured as a function of applied pressure from 100 Pa to 85 MPa. The effect of water content, in the range 4 to 18% (wet weight basis), on the compaction behaviour of the flakes was examined for pressures from 1 to 85 MPa. The data were analysed using different relationships between density and applied pressure in accordance with Peleg, Kawakita and Heckel. The Heckel deformation stress decreased as the water content increased up to 12% and became inaccurate at 18% water. The Peleg compressibility and Kawakita yield stress only showed a marked decrease from 12 to 18% water. Collectively, these results agree qualitatively with other observations of the decrease in stiffness of single flakes over this water content range.

Large-radius Weissenberg cameras equipped with image plates have become popular for the collection of X-ray diffraction from protein crystals. However, it is not always easy to ensure in either design or practice that the image plates assume cylindrical geometry with respect to the crystal rotation axis. This article describes an algorithm that is capable of correcting for general distortions in image-plate or camera geometry on these instruments

A nonneutral strongly magnetized cold electron collisional plasma confined in a cylindrical geometry with an applied axial magnetic field is considered. An expression for the radial distribution of the electron density is obtained. It is found that the radial profile of the electron density changes with time and in the limit tends to a step function.

In this report, we study the numerical solution of melting/solidification problems in cylindrical geometry by the heat balance integral method. The heat balance method can be applied to a range of problems, particularly to problems with symmetric geometries (cylindrical and spherical), and the accuracy obtained is usually sufficient for most practical situations. Good accuracy can be obtained by using a linear temperature profile with spatial sub‐divisions. We also discuss ways of improving the accuracy of the solutions and efficiency of the computations. The heat balance method also can be used when there is a singularity in the problem to provide small time approximation solutions.

Single event distributions were measured in neutron fields of different energies to appraise the response of Rossi type proportional counters operating in helix mode. Spectra acquired with tissue-equivalent and carbon walled counters operating in conventional and helix modes exemplify the intrinsic differences in chord length distributions for sensitive volumes of different shapes. An active volume in the form of an elongated cylinder was empirically assessed for the helix mode of operation following exposure to a known dose. This volume definition enabled conversion of pulse height data to absorbed dose spectra in lineal energy. Calibration of spectra was possible by identifying cut-off-edges discerned for different particle species. The dosimetric data were consistent with those obtained when running the counters conventionally and demonstrate the suitability of helix mode for time resolved kerma assessments in high energy neutron fields.

Expressions for the magnetization of a monolithic superconductor with anisotropic critical currents and a cylindrical geometery have been found. A transverse field geometry, along with field independent critical currents are assumed. Additionally, we restrict ourselves to the case of full field penetration, and thus demagnetization effects are ignored. Similarly to the calculation for the slab geometry, two regimes are found; (1) sample length is greater than a certain “transfer length”, and (2) sample length is shorter than the transfer length. Analytical expressions for the magnetization in both regimes, as well as linear approximations to these expressions, are found. These results are directly compared to the equations used to describe the finite slab geometry.

Using square zoning, the 2011 version of the kinetic package Tarantula matches cylinder data, cylinder dead zones, and cylinder failure with the same settings for the first time. The key is the use of maximum pressure rather than instantaneous pressure. Runs are at 40, 200 and 360 z/cm using JWL++ as the host model. The model also does run-to-detonation, thin-pulse initiation with a P-t curve and air gap crossing, all in cylindrical geometry. Two sizes of MSAD/LX-10/LX-17 snowballs work somewhat with these settings, but are too weak, so that divergent detonation is a challenge for the future. Butterfly meshes are considered but do not appear to solve the issue.

We obtain in both the scalar and vector photon models the analytical expressions for the initial cooperative decay rate and the cooperative Lamb shift for an ensemble of resonant atoms distributed uniformly in an infinite cylindrical geometry for the case that the initial state of the system is prepared in a phased state modulated in the direction of the cylindrical axis. We find that qualitatively the scalar and vector theories give different results.

Broad-band nondestructive ion detection based on induced image current measurement is performed in a quadrupole ion trap having cylindrical geometry. Spectra of krypton and acetophenone are shown to demonstrate the first use of nondestructive detection with a cylindrical ion trap.

We discuss the concept of infrared cloaking using nanosphere dispersed liquid crystal (NDLC) matematerial in cylindrical geometry. Preliminary results show that NDLC is a promising candidate for cloak design. Monte Carlo simulations are used for the design.

The conditions necessary for successful transmission of a planar detonation wave into a confined volume have been investigated. Detonation diffraction into a confined volume has not been as widely studied as detonation diffraction into an unconfined volume. Therefore, a new experiment was built to study detonation diffraction into a confined, cylindrical geometry. Of interest are the conditions necessary for the successful transformation of a planar detonation wave into a diverging cylindrical detonation wave as well as the measurement of the corresponding pressure profile on the endwall. Details on the new experimental facility are provided in this paper. Experiments have been performed using two different mixtures, C2H2 + 4 O2 and C2H2 + 2.5 O2, and the critical conditions necessary for successful transmission have been defined. It is shown that the critical conditions depend on two parameters, the primary detonation cell size ( ) and the gap width (w), and a correlation was obtained for the lean mixture as follows: w/ = 0.151w – 0.0944.

The analytical solution for the temperature field in an infinite solid medium which surrounds a cylindrical surface, determined by Carlslaw and Jaeger for the case of constant heat flux, is extended to the case of any time dependent heat flux. Then, with reference to a sinusoidally varying heat flux, the analytical solution is employed to validate a finite-element solution of the same problem, performed through COMSOL Multiphysics. Finally, the long term behaviour of BHE fields subjected to completely unbalanced winter and summer heat loads, in the absence of groundwater movement, is investigated by means of finite element simulations performed through COMSOL Multiphysics and a simple method based on the superposition of effects. Fields with few BHEs are considered, to complement the results of a recent study which refers to an infinite line, double line or square field.

Cancellous bones have a porous microstructure and can be modeled as linear elastic solid, heterogeneous and anisotropic. Few studies regarding the morphometric analysis of trabecular bone samples with 3D microtomography have been published so far. The technique has spread worldwide for the characterization of trabecular structures in studies related to bone quality and its relationship with metabolic diseases bone like osteoporosis. In our study cancellous bone samples with cubic and cylindrical geometry were extracted from bovine femur were used to investigate the structural arrangement of bone through high resolution x-ray 3D microtomography (μCT). Four trabecular microstructural parameters (tissue volume, bone volume, bone volume fraction and tissue surface) were measured by 2D (stereological method) and 3D morphometric analysis using the software CTan Analyser supplied by the manufacturer of the microtomograph (SkyScan, model 1172, Belgium). The measurements were done in three main directions (superior-inferior, medial-lateral and anterior-posterior) to investigate the correlation between the 2D and 3D morphometric analysis. The results show a high correlation between the analysis. The x-ray 3D microtomography technique has a great potential for the assessment of bone quality.

Inorganic nanotubes represent a fast developing field of nanotube (NT) investigations and a unique area of nanotechnology. The knowledge accumulated in the scientific community in the research of carbon NTs has facilitated the understanding of inorganic NTs and enabled the rapid development of their synthesis and possible applications. Although some geometrical similarities with carbon NTs exist, inorganic NTs represent a unique system with important peculiarities, from the growth mechanisms to the physical and chemical properties. Their structural properties – important for potential applications such as low-friction materials, safe containers, carriers in targeted medicine, as nanoreactors, and in strengthening fibers – are discussed in this chapter. The self-assembly and use of NTs as nanochannels are also described. Our increasing awareness of the possible health risks that nanomaterials represent for human health and the environment is briefly illustrated and recommendations for safe work with NTs are proposed.

Superconductors in a cylindrical geometry respond periodically to a cylinder-threading magnetic flux, with the period changing from hc/2e to hc/e depending on whether the Aharonov-Bohm effects are suppressed or not. We show that Holographic Superconductors present a similar phenomenon, and that the different periodicities follow from classical no-hair theorems. We also give the Ginzburg-Landau description of the period-doubling phenomenon., Comment: 4 pages, 3 figures; article published in Physical Review Letters

The enlargement and rupture of intracranial and abdominal aortic aneurysms constitutes a major medical problem. It has been suggested that enlargement and rupture are due to mechanical instabilities of the associated complex fluid-solid interaction in the lesions. In this paper, we examine a coupled fluid-structure mathematical model for a cylindrical geometry representing an idealized aneurysm using both analytical and numerical techniques. A stability analysis for this subclass of aneurysms is presented. It is shown that this subclass of aneurysms is dynamically stable both with and without a viscoelastic contribution to the arterial wall.

In this work we examine and validate a recently-published model for the junctionless (JL) nanowire FET with cylindrical geometry by carrying out extensive comparisons with TCAD simulation results over a wide range of impurity concentrations and device diameters.

The effects of compositional discontinuities of density and viscosity in the Earth's mantle on the ascent of mantle plume heads is studied using a boundary integral numerical technique. Three specific problems are considered: (1) a plume head rising away from a deformable interface, (2) a plume head passing through an interface, and (3) a plume head approaching the surface of the Earth. For the case of a plume attached to a free-surface, the calculated time-dependent plume shapesare compared with experimental results. Two principle modes of plume head deformation are observed: plume head elingation or the formation of a cavity inside the plume head. The inferred structure of mantle plumes, namely, a large plume head with a long tail, is characteristic of plumes attached to their source region, and also of buoyant material moving away from an interface and of buoyant material moving through an interface from a high- to low-viscosity region. As a rising plume head approaches the upper mantle, most of the lower mantle will quickly drain from the gap between the plume head and the upper mantle if the plume head enters the upper mantle. If the plume head moves from a high- to low-viscosity region, the plume head becomes significantly elongated and, for the viscosity contrasts thought to exist in the Earth, could extend from the 670 km discontinuity to the surface. Plume heads that are extended owing to a viscosity decrease in the upper mantle have a cylindrical geometry. The dynamic surface topography induced by plume heads is bell-shaped when the top of the plume head is at depths greater than about 0.1 plume head radii. As the plume head approaches the surface and spreads, the dynamic topography becomes plateau-shaped. The largest stresses are produced in the early stages of plume spreading when the plume head is still nearly spherical, and the surface expression of these stresses is likely to be dominated by radial extension. As the plume spreads, compressional stresses on the surface are produced beyond the edges of the plume; consequently, extensional features will be produced above the plume head and may be surrounded by a ring of compressional features.

Redundancy in the simplest form of a two‐dimensional TLM network is identified and a method of eliminating it is described. Results obtained using the non‐redundant algorithm are compared with those derived from the standard, redundant algorithm. The non‐redundant approach is extended to deal with non‐uniform elemental capacitance; a cylindrical geometry is taken as an example of this. The scope for and benefits of rendering TLM diffusion models non‐redundant are discussed.

The coupled transport of density and temperature perturbations in cylindrical geometry is considered and an analytic solution, valid in regions in which the perturbed sources do not vanish, is given. An application is made to JET ICRF power modulation experiments. Criteria for the validity of far-field solutions are derived.

A new multimode microwave applicator has been designed and constructed to provide efficient energy coupling and uniform heating of specimens at 2.45 GHz. The applicator is circular cylindrical with a diameter of 12.9 inches (32.8 cm) and a motorized endwall producing periodic variation of the cavity length between 7 inches (17.8 cm) and 13 inches (33.0 cm). The positions of the endwall cause 19 distinct and identified modes to be scanned. The close proximity of the resonant modes in this applicator as a function of the length of the applicator provides significant mode overlap in the presence of a load. The mode overlap results in a constant input impedance as the length of the cavity changes. The input impedance of the applicator can therefore be matched over a range of different loads.

The paper describes an experimental investigation into the thermal behavior of a three lobe profile bore bearing. Three geometries are considered, a symmetric, tilted and tilted with siderail geometry. The results are presented in a format which enables convenient comparison with predicted data and confirms the severity of the thermal excursions in the loaded lobe. Global behavior is also presented which demonstrates trends similar to those for a cylindrical geometry. The results confirm the effectiveness of the side rail in reducing lubricant sideflow while having only a marginal effect on thermal excursions.

Cultural Heritage diagnostics often involves the application of geophysical methods like ground penetrating radar along non-planar surfaces. Sometimes, as in the investigation of columns with a small radius, the basic assumption underlying the application of conventional processing algorithms (half-space geometry) is strongly violated. Although frequently overlooked, this implies that appropriate algorithms should be developed to take into account the additional data complexity arising from the unusual acquisition setting and exceptional care should be used in interpreting the radargrams. Through numerical and real data examples an in-depth analysis of reflection/diffraction features from buried and above-surface objects is performed in this paper.

The vector finite element method is used to solve the inhomogeneous Helmholtz equation to obtain the 3D circuit fields in resonant cavities. Numerical results will be shown for a cylindrical geometry that models the cavity gap and to confirm the theoretical error estimates.

The study shows the respective roles of skin and support of an ultrafiltration membrane in the retention mechanisms of bacteria (Escherichia coli). For this, pinholes defects of 5–200 μm in diameter were performed through ultrafiltration polymeric membranes and their impact was assessed on bacterial retention in a stirred cell when the transmembrane pressure is set at 0.5 bars. Various techniques have been used to make the defects such as a microhardness tester or femtosecond lasers. As long as the selective skin is not altered through its whole thickness, the membrane keeps a retention efficiency equivalent to the one of an uncompromised membrane. The retention by the macroporous support is also investigated. In case of membrane with defects of cylindrical geometry, experimental results are compared to calculated data obtained with a pore flow model, and the validity of this model is discussed.

We develop a new instrument that couple cylindrical fluorescence diffuse optical tomography to a micro XCT system. We focus on the effective coupling between both modalities via the fDOT algorithm. Quantitative results are provided.

A minimization problem modeling geometrically exact generalized continua of micromorphic type is considered. The solution consists of two fields, the elastic deformation φ of a given body and a tensorial field P which can model different additional features needed for a more reliable description of solids. For the solution of this minimization problem, a staggered algorithm is introduced which decouples the original problem into two separate problems. In each of these subproblems, one of the variables, φ or P, respectively, is kept fixed and the subproblem is solved for the remaining variables, i.e., P or φ, respectively. Each of the problems is discretized with finite elements. Numerical results are presented for a cubic and a cylindrical geometry (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

We report measurements of the specific heat of thin helium films adsorbed in the 0.2 µm pores of Anopore membranes. Over the temperature range of these studies, two specific heat anomalies, strongly dependent on helium film thickness, were found.

The macromolecular nature of humic substances is well established, and cylindrical geometry appears most likely although molecular dimensions have not been published. Previous analyses of acid-base titrations of humic acids have largely ignored the macromolecular nature of the humic molecule and the

Numerical solutions are described for three-dimensional MHD equilibria in the presence of resonant magnetic field perturbations. The effects of a realistic spectrum of resonant field errors are calculated for a range of current profiles in cylindrical geometry, and the results are benchmarked against toroidal calculations for two different current profiles. It is found that field errors of the magnitude existing in present day devices, and contemplated for future devices, can produce a set of magnetic islands occupying a significant fraction of the plasma cross-section. The calculations are applicable to those situations where flow effects are unimportant. The conditions under which this is the case are discussed, and implications for several cases of interest are considered

Experiments on the excitation of cylindrical and spherical solitons in a positive-ion\char21{}negative-ion\char21{}electron plasma are described. The results are in substantial agreement with the theoretical model proposed by Das and Singh [Aust. J. Phys. 44, 523 (1991)]. In addition, experiments on the oblique collision of solitons in a cylindrical geometry are described.

The resurgence of High Temperature Reactor (HTR) technology has prompted the development and application of modern calculation methodologies, many of which are already utilized in the existing power reactor industry, to HTR designs. To this end, the use of nodal diffusion methods for full core neutronic analysis is once again considered for both their performance and accuracy advantages. Recently a number of different approaches to Two-Dimensional (2D) and 3D multigroup cylindrical nodal diffusion methods were proposed by various institutions for use in HTR, and specifically Pebble Bed Modular Reactor (PBMR), reactor calculations. In this regard we may mention the NEM code from the Pennsylvania State University (PSU), based on the Nodal Expansion Method; and the OSCAR code from NECSA, utilizing a conformal mapping approach to the Analytic Nodal Method. In this work we will compare these two approaches in terms of accuracy and performance. Representative problems, selected to test the methods thoroughly, were devised and based on both a modified version of the PBMR 400 MW benchmark problem and a “cylindrisized” version of the IAEA two-group problem. The comparative results between OSCAR and NEM are given, focusing on global reactivity estimation, as well as power and flux errors as compared to reference finite-difference solutions. These results indicate that both OSCAR and NEM recover the global reference solution for the IAEA problem, and show power errors which are generally acceptable for nodal methods. For the PBMR problem the accuracy is similar, but some convergence difficulties are experienced at the outer boundaries of the system due to the very large dimensions of the reflector (when compared to typical water-moderated reactors). For both codes a significant performance increase was found as compared to finite-difference calculations, which is the method currently employed by the PBMR (Pty) Ltd company. In conclusion it seems that nodal methods have potential for use in the HTR analysis, and specifically PBMR calculational arena, although cylindrical geometry based nodal methods will have to develop toward maturity before becoming the industry standard.Copyright © 2008 by ASME

We study the effects of bending on single polarization fiber performance through the use of finite element method in conjunction with the perfectly matched layer (PML) in cylindrical geometry. The cylindrical PML used in this paper allows us to calculate the loss associated with each polarization mode at a given wavelength, specified bending diameter, and specific orientation. We identified a series of bending characteristics of the single polarization fiber by choosing different bending diameters and different orientations. We also conducted experiments to study some aspects of the bending. Good qualitative agreement between numerical and experimental results is found, which helps to understand fiber deployment conditions and can potentially facilitate new design efforts.

International audience; The goal of this paper is to present high-order cell-centered schemes for solving the equations of Lagrangian gas dynamics written in cylindrical geometry. A node-based discretization of the numerical fluxes is obtained through the computation of the time rate of change of the cell volume. It allows to derive finite volume numerical schemes that are compatible with the geometric conservation law (GCL). Two discretizations of the momentum equations are proposed depending on the form of the discrete gradient operator. The first one corresponds to the control volume scheme while the second one corresponds to the so-called area weighted scheme. Both formulations share the same discretization for the total energy equation. In both schemes, fluxes are computed using the same nodal solver which can be viewed as a two-dimensional extension of an approximate Riemann solver. The control volume scheme is conservative for momentum, total energy and satisfies a local entropy inequality in its first-order semi-discrete form. However, it does not preserve spherical symmetry. On the other hand, the area weighted scheme is conservative for total energy and preserves spherical symmetry for one-dimensional spherical flow on equiangular polar grid. The two-dimensional high-order extensions of these two schemes are constructed employing the generalized Riemann problem (GRP) in the acoustic approximation. Many numerical tests are presented in order to assess these new schemes. The results obtained for various representative configurations of one and two-dimensional compressible fluid flows show the robustness and the accuracy of our new schemes.

A comprehensive computational model for simulating magnetic drug targeting was developed and extensively tested in a cylindrical geometry. The efficiency for particle capture in a specific magnetic field and geometry was shown to be dependent on a single dimensionless number. The effect of secondary flows, a non-Newtonian viscosity and oscillatory flows were quantified. Simulations under the demanding flow conditions of the left coronary artery were performed. Using the properties of present-day magnetic carriers and superconducting magnets, approximately one third of 4μm particles could be captured with an external field. These promising results could open up the way to a minimally invasive treatment of coronary atherosclerosis.