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Artykuły w czasopismach na temat "Body fluids, mathematical models"
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Smith, D. J., E. A. Gaffney i J. R. Blake. "Mathematical modelling of cilia-driven transport of biological fluids". Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 465, nr 2108 (2.06.2009): 2417–39. http://dx.doi.org/10.1098/rspa.2009.0018.
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Cilia-driven flow occurs in the airway surface liquid, in the female and male reproductive tracts and enables symmetry-breaking in the embryonic node. Viscoelastic rheology is found in healthy states in some systems, whereas in others may characterise disease, motivating the development of mathematical models that take this effect into account. We derive the fundamental solution for linear viscoelastic flow, which is subsequently used as a basis for slender-body theory. Our numerical algorithm allows efficient computation of three-dimensional time-dependent flow, bending moments, power and particle transport. We apply the model to the large-amplitude motion of a single cilium in a linear Maxwell liquid. A relatively short relaxation time of just 0.032 times the beat period significantly reduces forces, bending moments, power and particle transport, the last variable exhibiting exponential decay with relaxation time. A test particle is propelled approximately one-fifth as quickly along the direction of cilia beating for scaled relaxation time 0.032 as in the Newtonian case, and mean volume flow is abolished, emphasizing the sensitivity of cilia function to fluid rheology. These results may have implications for flow in the airways, where the transition from Newtonian to viscoelastic rheology in the peri-ciliary fluid may reduce clearance.
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Purwati, Endah, i Sugiyanto Sugiyanto. "Pengembangan Model Matematika SIRD (Susceptibles-Infected-Recovery-Deaths) Pada Penyebaran Virus Ebola". Jurnal Fourier 5, nr 1 (1.04.2016): 23. http://dx.doi.org/10.14421/fourier.2016.51.23-34.
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Ebola is a deadly disease caused by a virus and is spread through direct contact with blood or body fluids such as urine, feces, breast milk, saliva and semen. In this case, direct contact means that the blood or body fluids of patients were directly touching the nose, eyes, mouth, or a wound someone open.
In this paper examined two mathematical models SIRD (Susceptibles-Infected-Recovery-Deaths) the spread of the Ebola virus in the human population. Both the mathematical model SIRD on the spread of the Ebola virus is a model by Abdon A. and Emile F. D. G. and research development model. This study was conducted to determine the point of disease-free equilibrium and endemic equilibrium point and stability analysis of the dots, knowing the value of the basic reproduction number (R0) and a simulation model using Matlab software version 6.1.0.450.
From the analysis of the two models, obtained the same point for disease-free equilibrium point with the stability of different points and different points for endemic equilibrium point with the stability of both the same point and the same value to the value of the basic reproduction number (R0). After simulating the model using Matlab software version 6.1.0.450, it can be seen changes in the behavior of the population at any time.
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Pietribiasi, Mauro, Jacek Waniewski i John K. Leypoldt. "Mathematical modelling of bicarbonate supplementation and acid-base chemistry in kidney failure patients on hemodialysis". PLOS ONE 18, nr 2 (24.02.2023): e0282104. http://dx.doi.org/10.1371/journal.pone.0282104.
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Acid-base regulation by the kidneys is largely missing in end-stage renal disease patients undergoing hemodialysis (HD). Bicarbonate is added to the dialysis fluid during HD to replenish the buffers in the body and neutralize interdialytic acid accumulation. Predicting HD outcomes with mathematical models can help select the optimal patient-specific dialysate composition, but the kinetics of bicarbonate are difficult to quantify, because of the many factors involved in the regulation of the bicarbonate buffer in bodily fluids. We implemented a mathematical model of dissolved CO2 and bicarbonate transport that describes the changes in acid-base equilibrium induced by HD to assess the kinetics of bicarbonate, dissolved CO2, and other buffers not only in plasma but also in erythrocytes, interstitial fluid, and tissue cells; the model also includes respiratory control over the partial pressures of CO2 and oxygen. Clinical data were used to fit the model and identify missing parameters used in theoretical simulations. Our results demonstrate the feasibility of the model in describing the changes to acid-base homeostasis typical of HD, and highlight the importance of respiratory regulation during HD.
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KORNAEVA, E. P., A. V. KORNAEV, I. N. STEBAKOV, S. G. POPOV, D. D. STAVTSEV i V. V. DREMIN. "CONCEPT OF A MECHATRONIC INSTALLATION FOR RESEARCHING THE RHEOLOGICAL PROPERTIES OF PHYSIOLOGICAL FLUIDS". Fundamental and Applied Problems of Engineering and Technology, nr 1 (2021): 83–95. http://dx.doi.org/10.33979/2073-7408-2021-345-1-83-95.
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The properties of physiological fluids, blood primarily, contain important information about the state of a body. This article deals with the development of a new portable device of inertial viscometer for the physiological fluids. Based on the analysis of mathematical and simulation models of viscous media flows in capillaries, recommendations for the choice of design parameters are formulated. Processing the data of a video capillaroscopy for the intralipid flow under conditions close to the conditions for measuring blood viscosity showed the possibility of using the laser speckle contrast imaging method to determine the velocity profile over the channel thickness. The results obtained have created sufficient grounds for the design of a mechatronic test rig and its information-measuring system.
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Sankar, D. S., i Yazariah Yatim. "Comparative Analysis of Mathematical Models for Blood Flow in Tapered Constricted Arteries". Abstract and Applied Analysis 2012 (2012): 1–34. http://dx.doi.org/10.1155/2012/235960.
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Pulsatile flow of blood in narrow tapered arteries with mild overlapping stenosis in the presence of periodic body acceleration is analyzed mathematically, treating it as two-fluid model with the suspension of all the erythrocytes in the core region as non-Newtonian fluid with yield stress and the plasma in the peripheral layer region as Newtonian. The non-Newtonian fluid with yield stress in the core region is assumed as (i) Herschel-Bulkley fluid and (ii) Casson fluid. The expressions for the shear stress, velocity, flow rate, wall shear stress, plug core radius, and longitudinal impedance to flow obtained by Sankar (2010) for two-fluid Herschel-Bulkley model and Sankar and Lee (2011) for two-fluid Casson model are used to compute the data for comparing these fluid models. It is observed that the plug core radius, wall shear stress, and longitudinal impedance to flow are lower for the two-fluid H-B model compared to the corresponding flow quantities of the two-fluid Casson model. It is noted that the plug core radius and longitudinal impedance to flow increases with the increase of the maximum depth of the stenosis. The mean velocity and mean flow rate of two-fluid H-B model are higher than those of the two-fluid Casson model.
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Sudi Mungkasi. "Modelling And Simulation of Topical Drug Diffusion in The Dermal Layer of Human Body". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 86, nr 2 (24.08.2021): 39–49. http://dx.doi.org/10.37934/arfmts.86.2.3949.
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We consider the problem of drug diffusion in the dermal layer of human body. Two existing mathematical models of the drug diffusion problem are recalled. We obtain that the existing models lead to inconsistent equations for the steady state condition. We also obtain that solutions to the existing models are unrealistic for some cases of the unsteady state condition, because negative drug concentrations occur due to the inappropriate assumption of the model. Therefore, in this paper, we propose a modified mathematical model, so that the model is consistent, and the solution is nonnegative for both steady and unsteady state conditions of the drug diffusion problem in the dermal layer of human body. For the steady state condition, the exact solution to the proposed model is given. For unsteady state condition, we use a finite difference method for solving the models numerically, where the discretisation is centred in space and forward in time. Simulation results confirm that our proposed model and method preserve the non-negativity of the solution to the problem, so the solution is more realistic than that of the old model.
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Khapalov, Alexander. "The well-posedness of a swimming model in the 3-D incompressible fluid governed by the nonstationary Stokes equation". International Journal of Applied Mathematics and Computer Science 23, nr 2 (1.06.2013): 277–90. http://dx.doi.org/10.2478/amcs-2013-0021.
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We introduce and investigate the well-posedness of a model describing the self-propelled motion of a small abstract swimmer in the 3-D incompressible fluid governed by the nonstationary Stokes equation, typically associated with low Reynolds numbers. It is assumed that the swimmer’s body consists of finitely many subsequently connected parts, identified with the fluid they occupy, linked by rotational and elastic Hooke forces. Models like this are of interest in biological and engineering applications dealing with the study and design of propulsion systems in fluids.
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Vispute, Devarsh M., Prem K. Solanki i Yoed Rabin. "Large surface deformation due to thermo-mechanical effects during cryopreservation by vitrification – mathematical model and experimental validation". PLOS ONE 18, nr 3 (9.03.2023): e0282613. http://dx.doi.org/10.1371/journal.pone.0282613.
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This study presents a simplified thermal-fluids (TF) mathematical model to analyze large surface deformations in cryoprotective agents (CPA) during cryopreservation by vitrification. The CPA deforms during vitrification due to material flow caused by the combined effects of thermal gradients within the domain, thermal contraction due to temperature, and exponential increase in the viscosity of the CPA as it is cooled towards glass transition. While it is well understood that vitrification is associated with thermo-mechanical stress, which might lead to structural damage, those large deformations can lead to stress concentration, further intensifying the probability to structural failure. The results of the TF model are experimentally validated by means of cryomacroscopy on a cuvette containing 7.05M dimethyl sulfoxide (DMSO) as a representative CPA. The TF model presented in this study is a simplified version of a previously presented thermo-mechanics (TM) model, where the TM model is set to solve the coupled heat transfer, fluid mechanics and solid mechanics problems, while the TF model omits further deformations in the solid state. It is demonstrated in this study that the TF model alone is sufficient to capture large-body deformations during vitrification. However, the TF model alone cannot be used to estimate mechanical stresses, which become significant only when the deformation rates become so small that the deformed body practically behaves as an amorphous solid. This study demonstrates the high sensitivity of deformation predictions to variation in material properties, chief among which are the variations of density and viscosity with temperature. Finally, this study includes a discussion on the possibility of turning on and off the TF and TM models in respective parts of the domain, in order to solve the multiphysics problem in a computationally cost-effective manner.
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Yakovlev, A. A., S. G. Postupaeva, V. N. Grebennikov i N. V. Fedorova. "DEVELOPMENT OF TECHNICAL SYSTEMS BASED ON HEURISTIC MODELING OF THE PHYSICAL OPERATION PRINCIPLE". IZVESTIA VOLGOGRAD STATE TECHNICAL UNIVERSITY, nr 8(243) (28.08.2020): 83–86. http://dx.doi.org/10.35211/1990-5297-2020-8-243-83-86.
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A logical-mathematical model has been developed to represent the physical principles of the operation of technical systems with a fluid and gas working body. Example of modeling a gas turbine twin-shaft installation. Heuristic modification methods for developing improved models of the physical principle of action are proposed.
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Knezevic, Darko, Aleksandar Milasinovic, Zdravko Milovanovic i Sasa Lalos. "The influence of thermodynamic state of mineral hydraulic oil on flow rate through radial clearance at zero overlap inside the hydraulic components". Thermal Science 20, suppl. 5 (2016): 1461–71. http://dx.doi.org/10.2298/tsci16s5461k.
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In control hydraulic components (servo valves, LS regulators, etc.) there is a need for precise mathematical description of fluid flow through radial clearances between the control piston and body of component at zero overlap, small valve opening and small lengths of overlap. Such a mathematical description would allow for a better dynamic analysis and stability analysis of hydraulic systems. The existing formulas in the literature do not take into account the change of the physical properties of the fluid with a change of thermodynamic state of the fluid to determine the flow rate through radial clearances in hydraulic components at zero overlap, a small opening, and a small overlap lengths, which leads to the formation of insufficiently precise mathematical models. In this paper model description of fluid flow through radial clearances at zero overlap is developed, taking into account the changes of physical properties of hydraulic fluid as a function of pressure and temperature. In addition, the experimental verification of the mathematical model is performed.
Rozprawy doktorskie na temat "Body fluids, mathematical models"
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Porumbel, Ionut. "Large Eddy Simulation of premixed and partially premixed combustion". Diss., Georgia Institute of Technology, 2006. http://hdl.handle.net/1853/14050.
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Large Eddy Simulation (LES) of bluff body stabilized premixed and partially premixed combustion close to the flammability limit is carried out in this thesis. The LES algorithm has no ad-hoc adjustable model parameters and is able to respond automatically to variations in the inflow conditions.
Algorithm validation is achieved by comparison with reactive and non-reactive experimental data.
In the reactive flow, two scalar closure models, Eddy Break-Up (EBULES) and Linear Eddy Mixing (LEMLES), are used and compared. Over important regions, the flame lies in the Broken Reaction Zone regime. Here, the EBU model assumptions fail. The flame thickness predicted by LEMLES is smaller and the flame is faster to respond to turbulent fluctuations, resulting in a more significant wrinkling of the flame surface. As a result, LEMLES captures better the subtle effects of the flame-turbulence interaction.
Three premixed (equivalence ratio = 0.6, 0.65, and 0.75) cases are simulated. For the leaner case, the flame temperature is lower, the heat release is reduced and vorticity is stronger. As a result, the flame in this case is found to be unstable. In the rich case, the flame temperature is higher, and the spreading rate of the wake is increased due to the higher amount of heat release
Partially premixed combustion is simulated for cases where the transverse profile of the inflow equivalence ratio is variable. The simulations show that for mixtures leaner in the core the vortical pattern tends towards anti-symmetry and the heat release decreases, resulting also in instability of the flame. For mixtures richer in the core, the flame displays sinusoidal flapping resulting in larger wake spreading.
More accurate predictions of flame stability will require the use of detailed chemistry, raising the computational cost of the simulation. To address this issue, a novel algorithm for training Artificial Neural Networks (ANN) for prediction of the chemical source terms has been implemented and tested. Compared to earlier methods, the main advantages of the ANN method are in CPU time and disk space and memory reduction.
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Obando, Vallejos Benjamín Alonso. "Mathematical models for the study of granular fluids". Tesis, Universidad de Chile, 2018. http://repositorio.uchile.cl/handle/2250/168158.
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Tesis para optar al grado de Doctor en Ciencias de la Ingeniería, Mención Modelación Matemática en cotutela con la Université de LorraineThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely: In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids: the viscous nature of the intersticial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is an inequality (due to the plasticity of the fluid), and it involves a free boundary (due to the motion of the rigid body). The proof is achieved using an approximated problem and passing it to the limit. The approximated problems consider the regularization of the convex terms in the Bingham fluid and by using a penalty method to take into account the presence of the rigid body. In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface. As in the second problem, the proof is achieved using an approximated problem and passing it to the limit. The approximated problems consider a regularization of the convective term and a penalty method to take into account the presence of the rigid body.
CONICYT PFCHA/Doctorado Nacional/2014 - 2114090 y por CMM - Conicyt PIA AFB170001
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Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274/document.
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Cette thèse vise à obtenir et à développer des modèles mathématiques pour comprendre certains aspects de la dynamique des fluides granulaires hétérogènes. Plus précisément, le résultat attendu consiste à développer trois modèles. Nous supposons dans un premier temps que la dynamique du matériau granulaire est modélisée à l’aide d’une approche fondée sur la théorie du mélange. D’autre part, pour les deux modèles restant, nous considérons que le fluide granulaire est modélisé à l’aide d’une approche multiphase associant des structures et des fluides rigides. Plus exactement : • Dans le premier modèle, nous avons obtenu un ensemble d’équations basées sur la théorie du mélange en utilisant des outils d’homogénéisation et une procédure thermodynamique. Ces équations reflètent deux propriétés essentielles des fluides granulaires : la nature visqueuse du fluide interstitiel et un comportement de type Coulomb de la composante granulaire. Avec nos équations, nous étudions le problème de Couette entre deux cylindres infinis d’un écoulement hétérogène granulaire dense, composé d’un fluide newtonien et d’une composante solide. • Dans le deuxième modèle, nous considérons le mouvement d’un corps rigide dans un matériau viscoplastique. Les équations 3D de Bingham modélisent ce matériau et les lois de Newton régissent le déplacement du corps rigide. Notre résultat principal est d’établir l’existence d’une solution faible pour le système correspondant. • Dans le troisième modèle, nous considérons le mouvement d’un corps rigide conducteur thermique parfait dans un fluide newtonien conducteur de la chaleur. Les équations 3D de Fourier-Navier-Stokes modélisent le fluide, tandis que les lois de Newton et l’équilibre de l’énergie interne modélisent le déplacement du corps rigide. Notre principal objectif dans cette partie est de prouver l’existence d’une solution faible pour le système correspondant. La formulation faible est composée de l’équilibre entre la quantité du mouvement et l’équation de l’énergie totale, qui inclut la pression du fluide, et implique une limite libre due au mouvement du corps rigide. Pour obtenir une pression intégrable, nous considérons une condition au limite de glissement de Navier pour la limite extérieure et l’interface mutuelleThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
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Obando, Vallejos Benjamin. "Mathematical models for the study of granular fluids". Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0274.
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Cette thèse vise à obtenir et à développer des modèles mathématiques pour comprendre certains aspects de la dynamique des fluides granulaires hétérogènes. Plus précisément, le résultat attendu consiste à développer trois modèles. Nous supposons dans un premier temps que la dynamique du matériau granulaire est modélisée à l’aide d’une approche fondée sur la théorie du mélange. D’autre part, pour les deux modèles restant, nous considérons que le fluide granulaire est modélisé à l’aide d’une approche multiphase associant des structures et des fluides rigides. Plus exactement : • Dans le premier modèle, nous avons obtenu un ensemble d’équations basées sur la théorie du mélange en utilisant des outils d’homogénéisation et une procédure thermodynamique. Ces équations reflètent deux propriétés essentielles des fluides granulaires : la nature visqueuse du fluide interstitiel et un comportement de type Coulomb de la composante granulaire. Avec nos équations, nous étudions le problème de Couette entre deux cylindres infinis d’un écoulement hétérogène granulaire dense, composé d’un fluide newtonien et d’une composante solide. • Dans le deuxième modèle, nous considérons le mouvement d’un corps rigide dans un matériau viscoplastique. Les équations 3D de Bingham modélisent ce matériau et les lois de Newton régissent le déplacement du corps rigide. Notre résultat principal est d’établir l’existence d’une solution faible pour le système correspondant. • Dans le troisième modèle, nous considérons le mouvement d’un corps rigide conducteur thermique parfait dans un fluide newtonien conducteur de la chaleur. Les équations 3D de Fourier-Navier-Stokes modélisent le fluide, tandis que les lois de Newton et l’équilibre de l’énergie interne modélisent le déplacement du corps rigide. Notre principal objectif dans cette partie est de prouver l’existence d’une solution faible pour le système correspondant. La formulation faible est composée de l’équilibre entre la quantité du mouvement et l’équation de l’énergie totale, qui inclut la pression du fluide, et implique une limite libre due au mouvement du corps rigide. Pour obtenir une pression intégrable, nous considérons une condition au limite de glissement de Navier pour la limite extérieure et l’interface mutuelleThis Ph.D. thesis aims to obtain and to develop some mathematical models to understand some aspects of the dynamics of heterogeneous granular fluids. More precisely, the expected result is to develop three models, one where the dynamics of the granular material is modeled using a mixture theory approach, and the other two, where we consider the granular fluid is modeled using a multiphase approach involving rigid structures and fluids. More precisely : • In the first model, we obtained a set of equations based on the mixture theory using homogenization tools and a thermodynamic procedure. These equations reflect two essential properties of granular fluids : the viscous nature of the interstitial fluid and a Coulomb-type of behavior of the granular component. With our equations, we study the problem of a dense granular heterogeneous flow, composed by a Newtonian fluid and a solid component in the setting of the Couette flow between two infinite cylinders. • In the second model, we consider the motion of a rigid body in a viscoplastic material. The 3D Bingham equations model this material, and the Newton laws govern the displacement of the rigid body. Our main result is the existence of a weak solution for the corresponding system. • In the third model, we consider the motion of a perfect heat conductor rigid body in a heat conducting Newtonian fluid. The 3D Fourier-Navier-Stokes equations model the fluid, and the Newton laws and the balance of internal energy model the rigid body. Our main result is the existence of a weak solution for the corresponding system. The weak formulation is composed by the balance of momentum and the balance of total energy equation which includes the pressure of the fluid, and it involves a free boundary (due to the motion of the rigid body). To obtain an integrable pressure, we consider a Navier slip boundary condition for the outer boundary and the mutual interface
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Lai, Wing-chiu Derek, i 黎永釗. "The propagation of nonlinear waves in layered and stratified fluids". Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B29750441.
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Zhang, Dongxiao. "Conditional stochastic analysis of solute transport in heterogeneous geologic media". Diss., The University of Arizona, 1993. http://hdl.handle.net/10150/186553.
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This dissertation develops an analytical-numerical approach to deterministically predict the space-time evolution of concentrations in heterogeneous geologic media conditioned on measurements of hydraulic conductivities (transmissivities) and/or hydraulic heads. Based on the new conditional Eulerian-Lagrangian transport theory by Neuman, we solve the conditional transport problem analytically at early time, and express it in pseudo-Fickian form at late time. The stochastically derived deterministic pseudo-Fickian mean concentration equation involves a conditional, space-time dependent dispersion tensor. The latter not only depends on properties of the medium and the velocity but also on the available information, and can be evaluated numerically along mean "particle" trajectories. The transport equation lends itself to accurate solution by standard Galerkin finite elements on a relatively coarse grid. This approach allows computing without using Monte Carlo simulation and explicitly the following: Concentration variance/covariance (uncertainty), origin of detected contaminant and associated uncertainty, mass flow rate across a "compliance surface", cumulative mass release and travel time probability distribution across this surface, uncertainty associated with the latter, second spatial moment of conditional mean plume about its center of mass, conditional mean second spatial moment of actual plume about its center of mass, conditional co-variance of plume center of mass, and effect of non-Gaussian velocity distribution. This approach can also account for uncertainty in initial mass and/or concentration when predicting the future evolution of a plume, whereas almost all existing stochastic models of solute transport assume the initial state to be known with certainty. We illustrate this approach by considering deterministic and uncertain instantaneous point and nonpoint sources in a two-dimensional domain with a mildly fluctuating, statistically homogeneous, lognormal transmissivity field. We take the unconditional mean velocity to be uniform, but allow conditioning on log transmissivity and hydraulic head data. Conditioning renders the velocity field statistically nonhomogeneous with reduced variances and correlation scales, renders the predicted plume irregular and non-Gaussian, and generally reduces both predictive dispersion and uncertainty.
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Havard, Stephen Paul. "Numerical simulation of non-Newtonian fluid flow in mixing geometries". Thesis, University of South Wales, 1989. https://pure.southwales.ac.uk/en/studentthesis/numerical-simulation-of-nonnewtonian-fluid-flow-in-mixing-geometries(eaee66ae-2e3d-44ba-9a5f-41d438749534).html.
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In this thesis, a theoretical investigation is undertaken into fluid and mixing flows generated by various geometries for Newtonian and non-Newtonian fluids, on both sequential and parallel computer systems. The thesis begins by giving the necessary background to the mixing process and a summary of the fundamental characteristics of parallel architecture machines. This is followed by a literature review which covers accomplished work in mixing flows, numerical methods employed to simulate fluid mechanics problems and also a review of relevant parallel algorithms. Next, an overview is given of the numerical methods that have been reviewed, discussing the advantages and disadvantages of the different methods. In the first section of the work the implementation of the primitive variable finite element method to solve a simple two dimensional fluid flow problem is studied. For the same geometry colour band mixing is also investigated. Further investigational work is undertaken into the flows generated by various rotors for both Newtonian and non-Newtonian fluids. An extended version of the primitive variable formulation is employed, colour band mixing is also carried out on two of these geometries. The latter work is carried out on a parallel architecture machine. The design specifications of a parallel algorithm for a MIMD system are discussed, with particular emphasis placed on frontal and multifrontal methods. This is followed by an explanation of the implementation of the proposed parallel algorithm, applied to the same fluid flow problems as considered earlier and a discussion of the efficiency of the system is given. Finally, a discussion of the conclusions of the entire accomplished work is presented. A number of suggestions for future work are also given. Three published papers relating to the work carried out on the transputer networks are included in the appendices.
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Fanelli, Francesco. "Mathematical analysis of models of non-homogeneous fluids and of hyperbolic equations with low regularity coefficients". Doctoral thesis, SISSA, 2012. http://hdl.handle.net/20.500.11767/4420.
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The present thesis is devoted to the study both of strictly hyperbolic operators with low regularity coefficients and of the density-dependent incompressible Euler system. On the one hand, we show a priori estimates for a second order strictly hyperbolic operator whose highest order coefficients satisfy a log-Zygmund continuity condition in time and a log-Lipschitz continuity condition with respect to space. Such an estimate involves a time increasing loss of derivatives...
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Fanelli, Francesco. "Mathematical analysis of models of non-homogeneous fluids and of hyperbolic equations with low regularity coefficients". Phd thesis, Université Paris-Est, 2012. http://tel.archives-ouvertes.fr/tel-00794508.
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The present thesis is devoted both to the study of strictly hyperbolic operators with low regularity coefficients and of the density-dependent incompressible Euler system. On the one hand, we show a priori estimates for a second order strictly hyperbolic operator whose highest order coefficients satisfy a log-Zygmund continuity condition in time and a log-Lipschitz continuity condition with respect to space. Such an estimate involves a time increasing loss of derivatives. Nevertheless, this is enough to recover well-posedness for the associated Cauchy problem in the space $H^infty$ (for suitably smooth second order coefficients).In a first time, we consider acomplete operator in space dimension $1$, whose first order coefficients were assumed Hölder continuous and that of order $0$only bounded. Then, we deal with the general case of any space dimension, focusing on a homogeneous second order operator: the step to higher dimension requires a really different approach. On the other hand, we consider the density-dependent incompressible Euler system. We show its well-posedness in endpoint Besov spaces embedded in the class of globally Lipschitz functions, producing also lower bounds for the lifespan of the solution in terms of initial data only. This having been done, we prove persistence of geometric structures, such as striated and conormal regularity, for solutions to this system. In contrast with the classical case of constant density, even in dimension $2$ the vorticity is not transported by the velocity field. Hence, a priori one can expect to get only local in time results. For the same reason, we also have to dismiss the vortex patch structure. Littlewood-Paley theory and paradifferential calculus allow us to handle these two different problems .A new version of paradifferential calculus, depending on a parameter $ggeq1$, is also needed in dealing with hyperbolic operators with nonregular coefficients. The general framework is that of Besov spaces, which includes in particular Sobolev and Hölder sets. Intermediate classes of functions, of logaritmic type, come into play as well
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Zipp, Robert Philip. "Turbulent mixing of unpremixed reactants in stirred tanks". Diss., The University of Arizona, 1989. http://hdl.handle.net/10150/184832.
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The turbulent mixing process between two liquid streams in a standard tank stirred by a Rushton turbine has been studied. Experimental measurements of concentration and segregation (fluctuating concentration) have been made for both reacting and non-reacting flows. For the non-reacting case, one stream was marked with a fluorescent dye; the local concentration was measured using a fluorescence technique and a bifurcated fiber optic probe of custom design. Measurements were taken at two axial-radial planes within the tank. In the reacting case, the second-order reaction between sodium hydroxide and hydrochloric acid was studied, and urinine acted as a fluorescent indicator which became non-fluorescent as the reaction proceeded. Numerical studies of the mixing in the laboratory-scale vessel were made. FLUENT, a general-purpose fluid flow modelling program, was used to simulate the flow within the tank. This program uses a k-epsilon closure of the turbulent momentum equations. The program was modified to allow the inclusion of a segregation balance equation. Using this segregation balance technique, the turbulent species balance equations were solved. The results of these simulations agreed with the experimental measurements in all regions except the region near the entrance jets, where the model could not adequately predict the fluid behavior. This study has successfully predicted the behavior of reacting fluids in a bench-scale turbulently mixed stirred tank by the implementation of a segregation balance throughout the entire domain.
Książki na temat "Body fluids, mathematical models"
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ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition (1995 Hilton Head, S.C.). Bio-medical fluids engineering: Presented at the 1995 ASME/JSME Fluids Engineering and Laser Anemometry Conference and Exhibition, August 13-18, 1995, Hilton Head, South Carolina. New York, N.Y: American Society of Mechanical Engineers, 1995.
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Galdi, Giovanni P., Tomáš Bodnár i Šárka Nečasová. Fluid-structure interaction and biomedical applications. Basel: Birkhäuser, 2014.
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Dunnett, S. J. The mathematics of blunt body sampling. Berlin: Springer-Verlag, 1988.
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Volobuev, A. N. Osnovy nessimetrichnoĭ gidromekhaniki. Saratov: SamLi︠u︡ksPrint, 2011.
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Intensivnostʹ vzaimodeĭstviĭ v zhidkikh sredakh organizma. Moskva: Akademii͡a︡ nauk SSSR, Otdel vychislitelʹnoĭ matematiki, 1989.
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Computational hydrodynamics of capsules and biological cells. Boca Raton: Chapman & Hall/CRC, 2010.
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Růžička, Michael. Electrorheological fluids: Modeling and mathematical theory. Berlin: Springer, 2000.
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NATO Advanced Study Institute on Computer Modelling of Fluids Polymers and Solids (1988 University of Bath). Computer modelling of fluids polymers and solids. Dordrecht: Kluwer Academic, 1990.
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Neu, John C. Training manual on transport and fluids. Providence, R.I: American Mathematical Society, 2010.
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Padula, Mariarosaria. Asymptotic stability of steady compressible fluids. Heidelberg: Springer, 2011.
Znajdź pełny tekst źródłaCzęści książek na temat "Body fluids, mathematical models"
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Pstras, Leszek, i Jacek Waniewski. "Integrated Model of Cardiovascular System, Body Fluids and Haemodialysis Treatment: Structure, Equations and Parameters". W Mathematical Modelling of Haemodialysis, 21–85. Cham: Springer International Publishing, 2019. http://dx.doi.org/10.1007/978-3-030-21410-4_2.
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George, Jacques. "Reminders on the Mechanical Properties of Fluids". W Mathematical Models, 1–33. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2013. http://dx.doi.org/10.1002/9781118557853.ch1.
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Zhuravkov, Michael, Yongtao Lyu i Eduard Starovoitov. "Mathematical Models of Plasticity Theory". W Mechanics of Solid Deformable Body, 149–97. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8410-5_7.
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Feireisl, Eduard, i Antonin Novotný. "Mathematical Models of Fluids in Continuum Mechanics". W Nečas Center Series, 3–11. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-94793-4_1.
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Bresch, Didier, Benoît Desjardins, Jean-Michel Ghidaglia, Emmanuel Grenier i Matthieu Hillairet. "Multi-Fluid Models Including Compressible Fluids". W Handbook of Mathematical Analysis in Mechanics of Viscous Fluids, 2927–78. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-13344-7_74.
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Bresch, D., B. Desjardins, J. M. Ghidaglia, E. Grenier i M. Hillairet. "Multi-fluid Models Including Compressible Fluids". W Handbook of Mathematical Analysis in Mechanics of Viscous Fluids, 1–52. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-10151-4_74-1.
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Percus, J. K. "A Class of Solvable Models of Fermion Fluids". W Recent Progress in Many-Body Theories, 283–95. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4613-0973-4_29.
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Boyer, Franck, i Pierre Fabrie. "Nonhomogeneous fluids". W Mathematical Tools for the Study of the Incompressible Navier-Stokes Equations and Related Models, 409–52. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-5975-0_6.
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Zhuravkov, Michael, Yongtao Lyu i Eduard Starovoitov. "Mathematical Models of Solid with Rheological Properties". W Mechanics of Solid Deformable Body, 101–47. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8410-5_6.
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Zhuravkov, Michael, Yongtao Lyu i Eduard Starovoitov. "Mathematical Models of the Theory of Elasticity". W Mechanics of Solid Deformable Body, 69–100. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-19-8410-5_5.
Pełny tekst źródłaStreszczenia konferencji na temat "Body fluids, mathematical models"
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Paez, Brandon, Arturo Rodriguez, Nicholas Dudu, Jose Terrazas, Richard Adansi, V. M. Krushnarao Kotteda, Julio C. Aguilar i Vinod Kumar. "Aerodynamic Performance of Design for a CO2 Dragster". W ASME 2021 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/fedsm2021-65793.
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Abstract The CO2 Dragster competition is performed at a national level as part of the Technology Student Association (TSA), and it seeks to increase and implement STEM skills for high school students. Students are expected to create CO2-powered Dragsters, which are placed on a 20-meter track to compete against each other. The CO2 Dragster consists of a pressure vessel containing CO2, which is placed in a pre-drilled cartridge located at the back of the vehicle. The CO2 propellant is used to provide thrust to the Dragster during the race, and sand smoothed balsawood material is used for the solid body of the Dragster. The CO2 Dragster competition is introduced at the high school level to provide students with a hands-on activity that allows them to learn and apply the fundamentals of fluid dynamics and solid mechanics. The students are placed in charge of designing a 3D model of their Dragster and are required to submit the 3D model with their respective drawings. In this paper, a mathematical, computational, and experimental analysis of a CO2 Dragster is provided. This research consisted of creating a shell model on NX 10, then inserted into ANSYS Fluent to simulate the flow around the model to identify and track the stagnation points, pressure loadings, and flow separation effects caused by the fluid interaction with the Dragster. Mathematical formulas were implemented to find the fracture of slim body CO2 Dragsters, using a coupling between fluid mechanics and solid mechanics, Fluid-Structure Interactions (FSIs). In conclusion, by creating a computational model, it is possible to drive dragster design by simulating different dragster designs’ computationally to improve its performance. Creating a computational functional model to simulate the Dragster, implementing mathematical formulas to understand the behavior, and experimentally evaluating the parameters based on performance will lead to more innovative practices of creating better Dragsters for this competition.
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Wickramasinghe, I. P. M., i Jordan M. Berg. "Mathematical Modeling of Electrostatic MEMS Actuators: A Review". W ASME 2010 Dynamic Systems and Control Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/dscc2010-4299.
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This review examines recent results on analytical modeling of electrostatic MEMS. Such modeling can include multiple coupled physics domains, including electrostatic forces, and lumped circuit models, structural elasticity, rigid body dynamics, or fluid mechanics. This review focuses on analytical models that provide the benefits of a closed-form expression trade rather than strive for the highest degree of accuracy for. Such models have been used successfully for parametric design, synthesis of dynamical models, and development of control laws. This review considers the role of mathematical modeling in several traditional and emerging areas for electrostatic MEMS: 1) analysis of pull-in, 2) effects of parasitics, 3) parametric resonance, 4) movable gate transistor or NEMFETs, and 5) repulsive actuation.
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Alzoubi, Mahmoud A., i Agus P. Sasmito. "Development and Validation of Enthalpy-Porosity Method for Artificial Ground Freezing Under Seepage Conditions". W ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83473.
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Groundwater flow has an undesirable effect on ice growth in artificial ground freezing (AGF) process: high water flow could hinder the hydraulic sealing between two freeze pipes. Therefore, a reliable prediction of the multiphysics ground behavior under seepage flow conditions is compulsory. This paper describes a mathematical model that considers conservation of mass, momentum, and energy. The model has been derived, validated, and implemented to simulate the multiphase heat transfer between freeze pipes and surrounded porous ground structure with and without the presence of groundwater seepage. The paper discusses, also, the influence of the coolant’s temperature, the spacing between two freeze pipes, and the seepage temperature on time needed to create a closed, frozen wall. The results indicate that spacing between two pipes and seepage velocity have the highest impact on the closure time and the frozen body width.
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Chhabra, Narender K., James R. Scholten i Jeffrey B. Lozow. "Wave-Generated Forces and Moments on Submersibles: Models for Dynamic Simulation at Periscope Depth". W ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-1257.
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Abstract Analysis of the wave-induced motion of underwater vehicles near the ocean surface is a difficult task. First, the action of the fluid must be decomposed into ideal (inviscid) and real (viscous) effects. Next, each effect must be modeled as to its interaction with the submerged body. The effect of the body on the waves must be considered. In shallow water, the ocean bottom has many effects: energy-dissipation tends to reduce wave height; land-proximity restricts the wave direction; and the bottom boundary changes the shape of the waves, attenuating the vertical (but not the horizontal) component of motion. This paper presents mathematical models for predicting realistic wave-generated forces and moments on submersible vehicles. Included are models which generate typical wave spectra for deep and shallow waters, models for wave kinematics as affected by flat or sloping bottoms, and models for forces and moments on submersibles due to these surface waves. Forces and moments are computed using two alternative methods. One is a fast method based on analytical integration of dynamic pressure forces over the surface of an elongated ellipsoidal body. It gives first-order forces and moments limited to horizontal and restrained bodies. The second method, based on the Froude-Krylov approach, uses numerical integration of dynamic pressures to give forces and moments on any shape hull in any attitude. Unlike the first method, it can be extended to include broaching of the sea surface by the body. Hydrodynamic forces due to an unrestrained body’s motion are accounted for with “added mass” terms. These mathematical models have been implemented in the C language in a real-time computer simulation. They are actively used to study the dynamic performance and control of submersibles at periscope depths.
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Harari, Isaac, i Gabriel Blejer. "Finite Element Methods for the Interaction of Acoustic Fluids With Elastic Solids". W ASME 1995 Design Engineering Technical Conferences collocated with the ASME 1995 15th International Computers in Engineering Conference and the ASME 1995 9th Annual Engineering Database Symposium. American Society of Mechanical Engineers, 1995. http://dx.doi.org/10.1115/detc1995-0394.
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Abstract Computation is essential to the solution of many problems of structural acoustics, particularly when wavelengths are of the same order as characteristic length scales. The development of finite element methods for large-scale computation of solutions to these problems should be preceded by a thorough analytical understanding of their performance in simplified settings in order to validate application to general configurations. Coupling such an analysis with the design of numerical methods that is based on understanding the underlying mathematical framework leads to the development of robust methods in which stability properties are enhanced while maintaining higher-order accuracy. In this work we develop finite element methods for exterior problems of time-harmonic acoustic-structure interaction. Exterior boundary conditions are derived from an exact relation between the solution and its derivatives on an artificial boundary by the DtN method, yielding an equivalent problem in a bounded region that is suitable for domain-based computation. Solutions to the equivalent problem are unique, precluding singular behavior in finite element models. Galerkin/least-squares technology is specialized to these problems in order to counter the numerical difficulties that result from employing traditional Galerkin methods. This is achieved by appending terms in least-squares form containing residuals of the Euler-Lagrange equations to the standard Galerkin formulation. The Galerkin/least-squares method is designed to yield dispersion-free finite element solutions to model problems, leading to superior performance on general, multi-dimensional configurations. Two one-dimensional model problems are investigated over a wide range of combinations of material properties of both media. In the first an exterior acoustic problem with impedance boundary conditions is analyzed, in order to study the influence of the elastic body on the acoustic medium. In the second, an elastic rod with an exterior acoustic medium is investigated in order to examine propagation from the solid to the fluid. The resulting method exhibits superior performance for fluid-solid interaction in multi-dimensional configurations. One version of the method offers particularly good representation of interface values.
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Niederer, Peter F., Kai-Uwe Schmitt, Markus H. Muser i Felix H. Walz. "The Possible Role of Fluid/Solid Interactions in Minor Cervical Spine Injuries". W ASME 2001 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2001. http://dx.doi.org/10.1115/imece2001/amd-25450.
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Abstract Minor soft tissue injuries of the cervical spine pose increasing problems in public health. Such injuries are conveyed particularly often in rear-end automobile collisions at low impact speeds and it has been established that they may be associated with long-term impairment Among the hypotheses put forward in order to explain the occurrence of potentially harmful neck injuries at loading levels whose severity is generally considered well below tolerance limits which hitherto have assumed to be valid, interactions between fluid and solid structures have been postulated as injury mechanism. As the solid structures of the human body, i.e., skeleton, muscles, etc., are being accelerated and deformed through the action of impact forces, the fluids contained therein (blood, cerebrospinal fluid, interstitial fluids) are gradually dragged along or displaced because of viscosity or pressure gradients which are built up in the deforming solids. Ensuing relative motions and changes of fluid volumes cause viscous shear stresses and pressure peaks which may have an adverse influence, e.g., on cellular membranes. This hypothesis is supported by a number of experimental findings. In this communication, mathematical modeling approaches are presented which are aimed at a quantification of fluid/solid interactions under loading conditions which approximate the impact situations of interest here. For this purpose, idealized fluid and solid systems are first considered which are exposed to a constant acceleration. The geometries are chosen such that analytic solutions can be obtained. Second, a detailed neck model is presented which includes vertebrae, discs, muscles, tendons as well as a representative fluid space (plexus venosus). The models are subjected to boundary conditions which correspond to typical low-speed rear-end impacts. It is found, that the level of shear stresses caused by fluids and acting on surfaces in fluid-filled bodies depends essentially on the size of the fluid spaces under consideration. Accelerations thereby exhibit a stronger influence than the duration during which they act. It cannot be excluded that critical levels are reached even in a low speed impact scenario. Calculated pressure peaks, in turn, remain within physiological limits.
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Kelasidi, Eleni, Gard Elgenes i Henrik Kilvær. "Fluid Parameter Identification for Underwater Snake Robots". W ASME 2018 37th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/omae2018-78070.
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Nowadays different types of unmanned underwater vehicles (UUVs), such as remotely operated vehicles (ROVs) and autonomous underwater vehicles (AUVs), are widely used for sub-sea inspection, maintenance, and repair (IMR) operations in the oil and gas industry, archaeology, oceanography and marine biology. Also, lately, the development of underwater snake robots (USRs) shows promising results towards extending the capabilities of conventional UUVs. The slender and multi-articulated body of USRs allows for operation in tight spaces where other traditional UUVs are incapable of operating. However, the mathematical model of USRs is more challenging compared to models of ROVs and AUVs, because of its multi-articulated body. It is important to develop accurate models for control design and analysis, to ensure the desired behaviour and to precisely investigate the locomotion efficiency. Modelling the hydrodynamics poses the major challenge since it includes complex and non-linear hydrodynamic effects. The existing analytical models for USRs consider theoretical values for the fluid coefficients and thus they only provide a rough prediction of the effects of hydrodynamics on swimming robots. In order to obtain an accurate prediction of the hydrodynamic forces acting on the links of the USRs, it is necessary to obtain the fluid coefficients experimentally. This paper determines the drag and added mass co-efficients of a general planar model of USRs. In particular, this paper presents methods for identifying fluid parameters based on both computational fluid dynamic (CFD) simulations and several experimental approaches. Additionally, in this paper, we investigate variations of the drag force modelling, providing more accurate representations of the hydrodynamic drag forces. The obtained fluid coefficients are compared to the existing estimates of fluid coefficients for a general model of USRs.
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Tan, X. G., Andrzej J. Przekwas, Gregory Rule, Kaushik Iyer, Kyle Ott i Andrew Merkle. "Modeling Articulated Human Body Dynamics Under a Representative Blast Loading". W ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-64331.
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Blast waves resulting from both industrial explosions and terrorist attacks cause devastating effects to exposed humans and structures. Blast related injuries are frequently reported in the international news and are of great interest to agencies involved in military and civilian protection. Mathematical models of explosion blast interaction with structures and humans can provide valuable input in the design of protective structures and practices, in injury diagnostics and forensics. Accurate simulation of blast wave interaction with a human body and the human body biodynamic response to the blast loading is very challenging and to the best of our knowledge has not been reported yet. A high-fidelity computational fluid dynamic (CFD) model is required to capture the reflections, diffractions, areas of stagnation, and other effects when the shock and blast waves respond to an object placed in the field. In this effort we simulated a representative free field blast event with a standing human exposed to the threat using the Second Order Hydrodynamic Automatic Mesh Refinement Code (SHAMRC). During the CFD analysis the pressure time history around the human body is calculated, along with the fragment loads. Subsequently these blast loads are applied to a fully articulated human body using the multi-physics code CoBi. In CoBi we developed a novel computational model for the articulated human body dynamics by utilizing the anatomical geometry of human body. The articulated human body dynamics are computed by an implicit multi-body solver which ensures the unconditional stability and guarantees the quadratic rate of convergence. The developed solver enforces the kinematic constraints well while imposing no limitation on the time step size. The main advantage of the model is the anatomical surface representation of a human body which can accurately account for both the surface loading and the surface interaction. The inertial properties are calculated using a finite element method. We also developed an efficient interface to apply the blast wave loading on the human body surface. The numerical results show that the developed model is capable of reasonably predicting the human body dynamics and can be used to study the primary injury mechanism. We also demonstrate that the human body response is affected by many factors such as human inertia properties, contact damping and the coefficient of friction between the human body and the environment. By comparing the computational results with the real scenario, we can calibrate these input parameters to improve the accuracy of articulated human body model.
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Jagani, Jakin, Elizabeth Mack, Jihyeon Gong i Alexandrina Untaroiu. "Effect of Stent Design Parameters on Hemodynamics and Blood Damage in a Percutaneous Cavopulmonary Assist Device". W ASME 2018 5th Joint US-European Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/fedsm2018-83210.
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Hypoplastic Right Heart Syndrome is a type of congenital heart defect where the right ventricle is underdeveloped in an infant to pump blood from the body to the lungs. The three-staged surgical Fontan procedure provides a temporary treatment; however, in most of the cases, a heart transplantation is required due to postoperative complications. Currently, there are no devices commercially available in the market to provide a therapeutic assistance to these patients until a donor heart is available. Thus, a novel dual propeller pump concept is developed to provide cavopulmonary assistance to these patients. The designed blood pump would be percutaneously inserted via the Femoral vein and deployed at the center of the Total Cavopulmonary Connection (TCPC). The two propellers, each placed in the Superior Vena Cava (SVC) and the Inferior Vena Cava (IVC) are connected by a single shaft and rotating at same speed. The device is supported with the help of a self-expanding stent whose outer walls are anchored to the inner walls of the IVC and the SVC. Each of the IVC and the SVC propeller without the stent provides a modest pressure augmentation of 5–6 mm Hg. To expand on this, the current study focusses on studying the effect of the introduction of stent around the propeller on the hemodynamic performance of the pump. Five different stent design parameters, viz. the strut thickness, width, number, the stent length and number of strut columns were selected for a range of values. Each of the design parameters was varied by keeping all others constant and equal to the base stent design. All the stent models were analysed to see their effect on pressure rise, flow pattern and blood damage using 3D CFD analysis. The blood damage potential for different studied designs was predicted using a non-linear mathematical power law model along with Lagrangian particle tracking to predict the blood flow path. The introduction of stent resulted in pressure reduction of around 0.4 and 0.2 mm Hg around the IVC and SVC propeller with an increase in blood damage index (BDI) by almost 2 times for the final dual propeller pump assembly. It was observed that the blood damage potential was directly related to the amount of pressure rise where the stent length, stent column number, strut width, and strut thickness had a converse effect showing a reduction in pressure rise and blood damage with their increment. While the number of struts gave a desirable effect of increasing pressure rise and reducing blood damage with its increment. The study also demonstrated that the introduction of stent around a circulatory pump increases the Wall Shear Stress (WSS) value at the stent-artery wall interface thereby preventing the occurrence of restenosis and thrombosis initiating due to very low WSS (< 0.5 Pa). Thus, this study acts as an initial step to design a protective stent support around a percutaneous assist device by analysing the sensitivity of stent design parameters on the hemodynamic performance of the pump.
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Aileni, Raluca maria, Alexandra Ene, George Suciu i Carmen Mihai. "SOFTWARE APPLICATION FOR TEXTILE INVASIVE DEVICE USED IN ADVANCED MEDICINE". W eLSE 2014. Editura Universitatii Nationale de Aparare "Carol I", 2014. http://dx.doi.org/10.12753/2066-026x-14-269.
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This paper presents a software application designed to solve the complex mathematical formulas applied to describe the parameters for textile medical devices used for invasive interventions. The fluid flow mathematical parameters will be used for obtaining an adaptive 3D model for fluid dynamic simulation in the human vessels. The objectives are to define all parameters involved in the process and model the 3D textile structure suitable for use as medical invasive device to replace the damaged blood vessels. The modeling starts from the assumption that the arteries have a perfect tubular structure. For the simulation we considered the ideal fluid (flow occurs at low pressure differences) with constant parameters. For description of the fluid flow through cardiovascular implants, there are extremely few mathematical models that can be applied, because hemodynamic parameters that characterize fluid (density, viscosity, pressure, speed of movement, flow) and blood vessels (diameter, elasticity, compliance) varies due to regulatory mechanisms of the body. The algorithm programming application was done by using FORTRAN programming subroutines and the advantages of computing power is employed by using a hybrid Cloud Grid Network solutions. The reason of using Grid is that Grid is suited for applications with parallel data computing that require many simultaneous independent calculations like formulas based of Bessel functions and different type of integrals. This software application is used to solve the problem of the calculation of the complex parameters that are used in the medical textile product modeling. This modeling is necessary before creating the real 3D artificial arteries prototypes. The goal of this software application is to facilitate the necessary structural modeling of textile parameters for complex invasive medical use.