Thèses sur le sujet « Inertial particle dynamics »
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Huck, Peter Dearborn. « Particle dynamics in turbulence : from the role of inhomogeneity and anisotropy to collective effects ». Thesis, Lyon, 2017. http://www.theses.fr/2017LYSEN073/document.
Texte intégralTurbulence is well known for its ability to efficiently disperse matter, whether it be atmospheric pollutants or gasoline in combustion motors. Two considerations are fundamental when considering such situations. First, the underlying flow may have a strong influence of the behavior of the dispersed particles. Second, the local concentration of particles may enhance or impede the transport properties of turbulence. This dissertation addresses these points separately through the experimental study of two different turbulent flows. The first experimental device used is the so-called von K\'arm\'an flow which consists of an enclosed vessel filled with water that is forced by two counter rotating disks creating a strongly inhomogeneous and anisotropic turbulence. Two high-speed cameras permitted the creation a trajectory data base particles that were both isodense and heavier than water but were smaller than the smallest turbulent scales. The trajectories of this data base permitted a study of the turbulent kinetic energy budget which was shown to directly related to the transport properties of the turbulent flow. The heavy particles illustrate the role of flow anisotropy in the dispersive dynamics of particles dominated by effects related to their inertia. The second flow studied was a wind tunnel seeded with micrometer sized water droplets which was used to study the effects of local concentration of the settling velocities of these particles. A model based on theoretical multi-phase methods was developed in order to take into account the role of collective effects on sedimentation in a turbulent flow. The theoretical results emphasize the role of coupling between the underlying flow and the dispersed phase
Lashgari, Iman. « Stability analysis and inertial regimes in complex flows ». Doctoral thesis, KTH, Fysiokemisk strömningsmekanik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-177850.
Texte intégralQC 20151127
Schaaf, Christian [Verfasser], Holger [Akademischer Betreuer] Stark, Holger [Gutachter] Stark et Roland [Gutachter] Netz. « Particle dynamics in inertial microfluidics / Christian Schaaf ; Gutachter : Holger Stark, Roland Netz ; Betreuer : Holger Stark ». Berlin : Technische Universität Berlin, 2020. http://d-nb.info/1219573906/34.
Texte intégralRamaprabhu, Praveen Kumar. « On the dynamics of Rayleigh-Taylor mixing ». Diss., Texas A&M University, 2003. http://hdl.handle.net/1969.1/378.
Texte intégralBagge, Joar. « Numerical simulation of an inertial spheroidal particle in Stokes flow ». Thesis, KTH, Numerisk analys, NA, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-180290.
Texte intégralPartikelsuspensioner förekommer i många sammanhang i naturen och industrin. I denna masteruppsats studeras rörelsen hos en enstaka stel sfäroidisk partikel i Stokesflöde numeriskt med hjälp av en randintegralmetod och en ny specialiserad kvadraturmetod som kallas quadrature by expansion (QBX). Metoden fungerar för masslösa eller tröga sfäroider, som kan placeras i ett godtyckligt underliggande Stokesflöde. En parameterstudie av QBX-metoden presenteras, tillsammans med valideringsfall för sfäroider i linjärt skjuvflöde och kvadratiskt flöde. QBX-metoden kan beräkna kraften och momentet på sfäroiden samt den resulterande stelkroppsrörelsen med små fel på kort tid, typiskt mindre än en sekund per tidssteg på en vanlig persondator. Nya resultat presenteras för rörelsen hos en trög sfäroid i kvadratiskt flöde, där skjuvningen till skillnad från linjärt skjuvflöde inte är konstant. Det visar sig att partikeltröghet medför en drift i sidled mot områden i fluiden med högre skjuvning.
Ferran, Amélie. « Dynamique des particules d'inertie dans une interface turbulente/non turbulente ». Electronic Thesis or Diss., Université Grenoble Alpes, 2023. http://www.theses.fr/2023GRALI102.
Texte intégralThis experimental project will investigate the dynamics of droplets at the interface between turbulent and non-turbulent regions, with shear. To conduct this research, we will utilize unique facilities and measurement techniques, namely two wind tunnels equipped with turbulence-generating systems that can be differentially activated to create a turbulent/non-turbulent interface. This collaboration will cover a wide range of turbulent intensity gradients, shear rates, and Reynolds numbers for studying the dynamics of inertial particles in turbulent/non-turbulent conditions. The study will produce data on various droplet sizes spanning the range of Stokes numbers, characterizing particle inertia relative to the micrometric scale of turbulence. Potential applications include fuel injection in energy conversion systems, industrial spray coating, warm rain formation in clouds, and sea spray in the surf zone
Li, Qing. « Near-wall dynamics of neutrally buoyant particles in a wall-normal flow ». Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0125.
Texte intégralTwo-phase suspensions encountered in various engineering applications(like crude oil extraction, elaboration of food, concrete or cosmetics), can exhibit rich dynamics when submitted to flow in complex geometries. Predicting the response of such heterogeneous material under flow is an important issue in view of applications. To build these predictive models, basic understanding of the dif- ferent scales is required for configurations such as pipe flow through an elbow or T-shape section, mixing a solid-liquid dispersion by a rotating impeller, etc. Suspension flows normal to an obstacle have seen limited attention with the carrier fluid being liquid phase. In this context, we examined particle dynamics in the well-known Hiemenz boundary-layer flow, with the aid of numerical simu- lations. We focused essentially on one or two neutrally buoyant particles, which are of finite size compared to the boundary layer thickness (particles have a finite inertia near the wall because they are forced to stop at the wall), and which are located at the symmetry axis of the flow. We used direct numerical simulations in order to measure the particle slip with respect to the local flow, the hydrodynamic force experienced by the particle and the energy loss during solvent-mediated particle-wall interaction. All these quantities were determined as unique functions of the ratio between the particle size and the thickness of the viscous boundary layer. When the particle size is increased, the simulations highlighted a transition of the particle dynamics from viscous damping to rebound, occurring for particle size O(). We established a model for the hydrodynamic force experienced by the incident particle, and for the restitution coefficient in wall-normal flow. For two identical particles on the axis, certain separations lead to particle collision before the lower (closer to wall) particle hits the wall; the resulting momentum exchange leads to larger impact velocity than for one particle. The simulations reveal that dynamics of the colliding pair includes unexpected rebound without contact with the wall for the lower of two particles, due to sheltering by the upper particle from drag allowing the pressure force to dominate
Vosskuhle, Michel. « Particle collisions in turbulent flows ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2013. http://tel.archives-ouvertes.fr/tel-00946618.
Texte intégralKilimnik, Alexander. « Cross stream migration of compliant capsules in microfluidic channels ». Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/43669.
Texte intégralPost, E. Rehmi 1966. « Inertial measurement via dynamics of trapped particles ». Thesis, Massachusetts Institute of Technology, 2003. http://hdl.handle.net/1721.1/29991.
Texte intégralIncludes bibliographical references (leaves 69-70).
We describe theoretical and practical aspects of the particle trap as an inertial sensor. The insight motivating this approach is that a trapped particle acts like a mass on a spring, but the restoring forces are provided by electrostatic fields. Exquisitely machined physical mechanisms can be replaced by carefully tuned mechanical physics. Such inertial sensors could be simpler to build yet exhibit superior performance because their operating parameters can be dynamically controlled. Most currently available inertial sensors are inherently planar devices that obtain no more than two degrees of motional sensitivity from a given proof mass. The availability of an accurate, inexpensive, integrated six-degree-of-freedom inertial sensor would enable new applications of inertial sensing that are presently either infeasible or unconsidered. By adding inertial terms to the Paul trap dynamics we derive classical observables that depend on the local acceleration field. We also confirm that these observables appear in practice, in what we believe to be the first electrodynamic particle trap accelerometer. An important (and unusual) aspect of our accelerometer is its dynamic tunability: its effective spring constant depends on the trap drive parameters. Our roughly constructed trap also exhibits a large region of linear response to acceleration, and we present evidence suggesting that our accelerometer has performance comparable to commercially available sensors.
by Ernest Rehmatulla Post.
Ph.D.
Skála, Adam. « Analýza inerčního odlučovače částic na vstupu vzduchu do turbovrtulového motoru ». Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-400827.
Texte intégralMora-Paiba, Daniel. « Clustering and settling dynamics of inertial particles under turbulence ». Thesis, Université Grenoble Alpes, 2020. https://thares.univ-grenoble-alpes.fr/2020GRALI044.pdf.
Texte intégralTurbulent particle laden flows are widespread in industrial applications, and natural phenomena. Over the last decades, two observations: preferential concentration, and particle settling velocity modification have stood out as the most relevant consequences of such particle - turbulence interactions. Given the complexity of the problem, this work is composed of four work packages.The first package involves a pitfall analysis of the Vorono"{i} tessellation method, which is widely used to quantify preferential concentration. We found some pitfalls that compromise the results of the analysis using uni-dimensional records. In addition, we propose a new method to disentangle turbulence driven clusters from random spatial fluctuations, a common problem reported by other researchers.The second package involve the analysis of the carrier phase turbulence in our wind tunnel facility. In this regard, we conjecture that the different turbulence generators (active, open, and passive grids) do change the turbulence cascade, and thereby, they could impact the particles preferential concentration and settling behavior. To this aim, we have analysed active grid generated flows, and found that an active grid left open (with minimum blockage) exhibits scalings similar to those found in fractal grids. Moreover, The integral length scale could not be easily computed for active grid generated flows using triple random protocols due to the behavior of the autocorrelation function in such flows, which does not cross zero. We propose a new method to tackle this problem which could be easily applied in a myriad of situations.The third package consist of estimating the turbulent dissipation rate on the carrier phase due to the particle presence. By means of an extension of the Rice theorem, which relates the Taylor length scale with the average distance between zero crossings, we have proposed a method to estimate the carrier phase turbulence in the presence of particles. This method uses particle datasets recorded by phase doppler interferometry. Our results are consistent with previous experiments, and numerical simulations.The fourth package refers to the particle settling modification. We found that the Taylor Reynolds number Re_lambda is the leading order contributor the particles settling modification: at increasing values of Re_lambda the settling velocity of the particles is reduced. Also, at increasing values of Re_lambda the boundaries between positive, and negative particle settling modification shifts to smaller values of the Rouse number Ro=V_T/u
Rosén, Tomas. « The influence of inertia on the rotational dynamics of spheroidal particles suspended in shear flow ». Licentiate thesis, KTH, Mekanik, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-143663.
Texte intégralFlöden med dispergerade partiklar påträffas i många industriella, biologiska och geofysiska tillämpningar. Kunskap om hur dessa flöden beter sig kan bl.a. leda till förbättrade materialprocesser, bättre förutsägelser om hjärt- och kärlsjukdomar eller mer noggranna väderprognoser. Dessa flödens egenskaper beror på hur enskilda partiklar rör sig i en fluid och speciellt hur de är fördelade både i termer av position och, om de är icke-sfäriska, i termer av orientering. Mycket är redan känt om rörelsen av perfekt sfäriska partiklar. För icke-sfäriska partiklar är det inte bara translationen som är av intresse utan det är även viktigt att veta hur partiklarna roterar till följd av lokala hastighetsgradienter. Sådana studier har tidigare varit begränsade av antagandet att partiklarna är extremt små jämfört med fluidens typiska längdskalor. I denna gräns kan både partikelns och fluidens tröghet antas försumbar. Den här avhandlingen ger en komplett bild av hur en sfäroidisk partikel (en partikel som beskrivs av en rotation av en ellips runt en av dess huvudaxlar) beter sig i ett linjärt skjuvflöde när tröghetseffekter inkluderas. Resultaten har erhållits genom numeriska simuleringar. Det visar sig att detta enkla problem är väldigt rikt på olika dynamiska beteenden med flera stabila rotationstillstånd som uppstår tilll följd av både partikel- och fluidtröghet. Inverkan av partikeltröghet leder till en rotation där massan av partikeln är koncentrerad så långt ifrån rotationsaxeln som möjligt, d.v.s. en rotation runt lillaxeln. Den typiska inverkan av fluidtröghet är istället att fluiden försöker påtvinga partikeln en rotation där strömlinjer förblir så raka som möjligt. Primärt leder detta till att partikeln istället roterar runt storaxeln. Beroende på rotationstillstånd, så har partikeln även olika inverkan på den märkbara viskositeten av partikeldispersionen. De olika övergångarna och bifurkationerna mellan rotationstillstånd är karaktäriserade i termer av icke-linjär dynamik, vilket visar på att partikelrörelserna förmodligen kan beskrivas med en reducerad modell. Resultaten i denna avhandling är därför fundamental kunskap och ett nödvändigt steg mot att förstå beteendet av flöden med dispergerade, icke-sfäriska partiklar.
QC 20140328
Sumbekova, Sholpan. « Clustering of inertial sub-Kolmogorov particles : structure of clusters and their dynamics ». Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAI093/document.
Texte intégralThis PhD thesis investigates the phenomena of preferential concentration and settling of sub-Kolmogorov inertial particles transported in a turbulent flow. To this end, experiments have been carried out in active-grid-generated turbulence in a wind-tunnel, seeded with water droplets. Preferential concentration manifests itself as the emergence of spatial segregation of the particles, which where initially homogeneously seeded in the carrier flow, leading to clusters and voids. A particular effort has been put in disentangling the roles of particles inertia, of turbulence and of collective effects on the emergence of clustering and the modification of settling velocity and in investigating the interplay between clustering and settling. Four main non-dimensional parameters have been varied to establish the role of each in the clustering process and on the settling of the particles: the Rouse number $Ro$, representing the ratio of the settling velocity of the particles to the fluctuating velocity of the fluid ; the Stokes number $St$ , quantifying particle inertia as the ratio of the particle response time to the flow dissipative time scale ; the Reynolds number $Re_lambda$ representing the degree of turbulence and the volume fraction $phi_v$ representing the concentration of the particles in the two-phase flow.Two experimental techniques (Lagrangian Particle Tracking and Phase Doppler Interferometry) are used to acquire data and diagnose the clustering and settling properties of the dispersed droplets.2D-Lagrangian Particle Tracking has been performed using high-speed visualization of the dispersed droplets in a laser sheet. This gives access to simultaneous statistics of particles spatial distribution and velocity. Clustering has been quantified using Voronoï tessellation and quantitative scalings on the dependency of clustering intensity and clusters dimensions on $St$, $Re_lambda$ and $phi_v$ are found. They show a strong influence of $Re_lambda$ and volume fraction $phi_v$ but a weak effect of $St$. This finding is consistent with a leading role of the “sweep-stick” mechanism in the clustering process, as proposed by Vassilicos. Furthermore, conditional analysis of the velocities of particles within clusters and voids has been performed showing that clusters tend to settle faster than voids, pointing to the role of collective effects in the enhancement of settling.Phase Doppler Interferometry has then been used to further analyse velocity statistics, and particle concentration field conditioned on particle diameter. Enhancement of the settling velocity for small diameters is observed, in agreement with previous studies. On the contrary, for larger particles settling velocity is found to be hindered. This indicates a subtle intrication of several possible mechanisms affecting the settling, including preferential sweeping, loitering and collective effects
Seltz, Andréa. « Application of deep learning to turbulent combustion modeling of real jet fuel for the numerical prediction of particulate emissions Direct mapping from LES resolved scales to filtered-flame generated manifolds using convolutional neural networks Solving the population balance equation for non-inertial particles dynamics using probability density function and neural networks : application to a sooting flame ». Thesis, Normandie, 2020. http://www.theses.fr/2020NORMIR08.
Texte intégralWith the climate change emergency, pollutant and fuel consumption reductions are now a priority for aircraft industries. In combustion chambers, the chemistry and soot modeling are critical to correctly quantify engines soot particles and greenhouse gases emissions. This thesis aimed at improving aircraft numerical pollutant tools, in terms of computational cost and prediction level, for engines high fidelity simulations. It was achieved by enhancing chemistry reduction tools, allowing to predict CO emissions of an aircraft engines at affordable cost for the industry. Next, a novel closure model for unresolved terms in the LES filtered transport equations is developed, based on neural networks (NN), to propose a better flame modeling. Then, an original soot model for engine high fidelity simulations is presented, also based on NN. This new model is applied to a one-dimensional premixed sooted flame, and finally to an industrial combustion chamber LES with measured soot comparison
Djeddou, Mokhtar. « Étude de la dynamique des polluants particulaires dans un habitacle automobile ». Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0231.
Texte intégralAir pollution, especially that caused by fine and ultrafine particles, has significant deleterious effects on human health. Several studies have established a direct link between exposure to particulate pollution and various respiratory and cardiovascular diseases. Within vehicles, the threat is even more concerning due to the significant concentrations of particulate pollutants recorded. Therefore, improving air quality inside vehicle cabins is now a major priority for automotive manufacturers. In this context, this study aims to understand the interior environment of vehicles by characterizing the spatial distribution of pollutants, particularly fine and ultrafine particles, as a function of their size and parameters such as flow topology and turbulence level. This knowledge will be crucial for targeting localized air purification solutions, optimizing the placement of the micro-sensors that will equip future vehicles, and providing solutions for the more effective management of filtration systems as a function of the distribution and concentrations of these particles in the car cabin. First, special attention was devoted to modeling the single-phase flow. Two numerical modeling approaches have been adopted: the RANS (Reynolds Averaged Navier-Stokes) approach, based on solving the mean flow fields of the Navier-Stokes equations, and the LES (Large Eddy Simulation) approach, which involves solving the large structures containing the major part of the kinetic energy and modeling the contributions of the smaller scales. In the case of the RANS approach, various closure models, of first- and second-order, have been tested and compared. Furthermore, the turbulence structure of the flow inside the car cabin has been analyzed using Lumley's Anisotropy Invariant Mapping method (AIM). Finally, to validate the results of the numerical models, a velocity field measurement campaign, based on hot-wire anemometry technique, was conducted inside the cabin of an SUV-type car. Next, the dynamics of particulate pollutants in the car cabin was studied using the Diffusion-Inertia Model (DIM). This Eulerian model of inertial particle diffusion takes into account various transport mechanisms, including transport by the mean field, the effect of volume forces (i.e., gravity), particle deviation from fluid streamline (centrifugal effects), Brownian and turbulent diffusion, and turbophoresis or transport by turbulent kinetic energy gradients. The model was first validated on standard configurations such as dispersion in small-scale ventilated enclosures, deposition in 90° circular bends, and particle transport in a round jet flow. The model was then applied to simulate particle transport inside a large-scale vehicle. The influence of particle size on internal concentration fields was first analyzed. Then, the influence of passenger presence was studied. Finally, a particle concentration measurement campaign was conducted in the cabin to assess the relevance of the two-phase model. This study has led to the development of a complete model for simulating the dispersion of particulate pollutants inside a car cabin based on ventilation conditions and particle characteristics
Rosén, Tomas. « Angular dynamics of non-spherical particles in linear flows related to production of biobased materials ». Doctoral thesis, KTH, Linné Flow Center, FLOW, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-193124.
Texte intégralQC 20160929
Tallapragada, Phanindra. « Identifying dynamical boundaries and phase space transport using Lagrangian coherent structures ». Diss., Virginia Tech, 2010. http://hdl.handle.net/10919/28891.
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Bordes, Guilhem. « Interactions non-linéaires d'ondes et tourbillons en milieu stratifié ou tournant ». Phd thesis, Ecole normale supérieure de lyon - ENS LYON, 2012. http://tel.archives-ouvertes.fr/tel-00733175.
Texte intégralLovalenti, Philip Michael. « Inertial effects on particle dynamics ». Thesis, 1993. https://thesis.library.caltech.edu/3286/1/Lovalenti_pm_1993.pdf.
Texte intégralParisi, Giovanni [Verfasser]. « Investigations on particle dynamics in a high intensity heavy ion linac for inertial fusion / Giovanni Parisi ». 2005. http://d-nb.info/97696581X/34.
Texte intégralAbbas-Pour, Nima. « A Numerical Model for Oil/water Separation from an Accelerating Oil-coated Solid Particle ». Thesis, 2013. http://hdl.handle.net/1807/42657.
Texte intégralZahnow, Jens C. [Verfasser]. « Aggregation and fragmentation dynamics of inertial particles in fluid flows / von Jens C. Zahnow ». 2010. http://d-nb.info/1010475126/34.
Texte intégralOratis, Alexandros. « Beams and bubbles : interplay between elastic, inertial, viscous, and interfacial mechanics ». Thesis, 2021. https://hdl.handle.net/2144/42596.
Texte intégralGupta, Anupam. « Numerical Studies of Problems in Turbulence : 1) Fluid Films with Polymer Additives ; 2) Fluid Films with Inertial and Elliptical Particles ; 3) Scaled Vorticity Moments in Three- and Two-dimensional Turbulence ». Thesis, 2013. http://etd.iisc.ac.in/handle/2005/2843.
Texte intégralGupta, Anupam. « Numerical Studies of Problems in Turbulence : 1) Fluid Films with Polymer Additives ; 2) Fluid Films with Inertial and Elliptical Particles ; 3) Scaled Vorticity Moments in Three- and Two-dimensional Turbulence ». Thesis, 2013. http://hdl.handle.net/2005/2843.
Texte intégralRahaman, Md Masiur. « Dynamic Flow Rules in Continuum Visco-plasticity and Damage Models for Poly-crystalline Solids ». Thesis, 2017. http://etd.iisc.ac.in/handle/2005/4240.
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