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Computational fluid dynamics

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https://www.readbyqxmd.com/read/28644375/gaden-a-3d-gas-dispersion-simulator-for-mobile-robot-olfaction-in-realistic-environments
#1
Javier Monroy, Victor Hernandez-Bennets, Han Fan, Achim Lilienthal, Javier Gonzalez-Jimenez
This work presents a simulation framework developed under the widely used Robot Operating System (ROS) to enable the validation of robotics systems and gas sensing algorithms under realistic environments. The framework is rooted in the principles of computational fluid dynamics and filament dispersion theory, modeling wind flow and gas dispersion in 3D real-world scenarios (i.e., accounting for walls, furniture, etc.). Moreover, it integrates the simulation of different environmental sensors, such as metal oxide gas sensors, photo ionization detectors, or anemometers...
June 23, 2017: Sensors
https://www.readbyqxmd.com/read/28643335/a-review-of-hemolysis-prediction-models-for-computational-fluid-dynamics
#2
REVIEW
Hai Yu, Sebastian Engel, Gábor Janiga, Dominique Thévenin
Flow-induced hemolysis is a crucial issue for many biomedical applications; in particular, it is an essential issue for the development of blood-transporting devices such as left ventricular assist devices, and other types of blood pumps. In order to estimate red blood cell (RBC) damage in blood flows, many models have been proposed in the past. Most models have been validated by their respective authors. However, the accuracy and the validity range of these models remains unclear. In this work, the most established hemolysis models compatible with computational fluid dynamics of full-scale devices are described and assessed by comparing two selected reference experiments: a simple rheometric flow and a more complex hemodialytic flow through a needle...
June 23, 2017: Artificial Organs
https://www.readbyqxmd.com/read/28643237/small-airway-absorption-and-microdosimetry-of-inhaled-corticosteroid-particles-after-deposition
#3
P Worth Longest, Michael Hindle
PURPOSE: To predict the cellular-level epithelial absorbed dose from deposited inhaled corticosteroid (ICS) particles in a model of an expanding and contracting small airway segment for different particle forms. METHODS: A computational fluid dynamics (CFD)-based model of drug dissolution, absorption and clearance occurring in the surface liquid of a representative small airway generation (G13) was developed and used to evaluate epithelial dose for the same deposited drug mass of conventional microparticles, nanoaggregates and a true nanoaerosol...
June 22, 2017: Pharmaceutical Research
https://www.readbyqxmd.com/read/28638167/computational-fluid-dynamics-analysis-of-the-venturi-dustiness-tester
#4
Prahit Dubey, Urmila Ghia, Leonid A Turkevich
Dustiness quantifies the propensity of a finely divided solid to be aerosolized by a prescribed mechanical stimulus. Dustiness is relevant wherever powders are mixed, transferred or handled, and is important in the control of hazardous exposures and the prevention of dust explosions and product loss. Limited quantities of active pharmaceutical powders available for testing led to the development (at University of North Carolina) of a Venturi-driven dustiness tester. The powder is turbulently injected at high speed (Re ~ 2 × 10(4)) into a glass chamber; the aerosol is then gently sampled (Re ~ 2 × 10(3)) through two filters located at the top of the chamber; the dustiness index is the ratio of sampled to injected mass of powder...
May 2017: Powder Technology
https://www.readbyqxmd.com/read/28636625/comparison-study-of-exhaust-plume-impingement-effects-of-small-mono-and-bipropellant-thrusters-using-parallelized-dsmc-method
#5
Kyun Ho Lee
A space propulsion system is important for the normal mission operations of a spacecraft by adjusting its attitude and maneuver. Generally, a mono- and a bipropellant thruster have been mainly used for low thrust liquid rocket engines. But as the plume gas expelled from these small thrusters diffuses freely in a vacuum space along all directions, unwanted effects due to the plume collision onto the spacecraft surfaces can dramatically cause a deterioration of the function and performance of a spacecraft. Thus, aim of the present study is to investigate and compare the major differences of the plume gas impingement effects quantitatively between the small mono- and bipropellant thrusters using the computational fluid dynamics (CFD)...
2017: PloS One
https://www.readbyqxmd.com/read/28623871/simple-computing-of-the-viscosity-of-water-dioxane-mixtures-according-to-a-fluctuating-spc-e-ih-interstitial-model
#6
Anis Ghazouani, Jalel M'halla
In this contribution, we propose a new simple and fast computing approach to model liquid water and water-1,4 dioxane mixture, which is intermediate between molecular dynamics calculation and lattice fluid H-bonding theory in which water molecules are arranged according to a fluctuating hexagonal Ih network. It generalizes the interstitial mixture models of Samoilov and Pauling by increasing the number of spatial configurations into the space of phases due to the addition of rotations and vibrations of the molecules around their equilibrium positions...
June 17, 2017: Journal of Computational Chemistry
https://www.readbyqxmd.com/read/28623038/perfusion-kinetics-in-human-brain-tumor-with-dce-mri-derived-model-and-cfd-analysis
#7
A Bhandari, A Bansal, A Singh, N Sinha
Cancer is one of the leading causes of death all over the world. Among the strategies that are used for cancer treatment, the effectiveness of chemotherapy is often hindered by factors such as irregular and non-uniform uptake of drugs inside tumor. Thus, accurate prediction of drug transport and deposition inside tumor is crucial for increasing the effectiveness of chemotherapeutic treatment. In this study, a computational model of human brain tumor is developed that incorporates dynamic contrast enhanced-magnetic resonance imaging (DCE-MRI) data into a voxelized porous media model...
May 25, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28620181/hair-bundles-of-cochlear-outer-hair-cells-are-shaped-to-minimize-their-fluid-dynamic-resistance
#8
Nikola Ciganović, Amanuel Wolde-Kidan, Tobias Reichenbach
The mammalian sense of hearing relies on two types of sensory cells: inner hair cells transmit the auditory stimulus to the brain, while outer hair cells mechanically modulate the stimulus through active feedback. Stimulation of a hair cell is mediated by displacements of its mechanosensitive hair bundle which protrudes from the apical surface of the cell into a narrow fluid-filled space between reticular lamina and tectorial membrane. While hair bundles of inner hair cells are of linear shape, those of outer hair cells exhibit a distinctive V-shape...
June 15, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28619665/computer-modelling-of-electro-osmotically-augmented-three-layered-microvascular-peristaltic-blood-flow
#9
Dharmendra Tripathi, Abhilesh Borode, Ravinder Jhorar, O Anwar Bég, Abhishek Kumar Tiwari
A theoretical study is presented here for the electro-osmosis modulated peristaltic three-layered capillary flow of viscous fluids with different viscosities in the layers. The layers considered here are the core layer, the intermediate layer and the peripheral layer. The analysis has been carried out under a number of physical restrictions viz. Debye-Hückel linearization (i.e. wall zeta potential ≤25mV) is assumed sufficiently small, thin electric double layer limit (i.e. the peripheral layer is much thicker than the electric double layer thickness), low Reynolds number and large wavelength approximations...
June 12, 2017: Microvascular Research
https://www.readbyqxmd.com/read/28618515/numerical-simulations-of-vesicle-and-bubble-dynamics-in-two-dimensional-four-roll-mill-flows
#10
Yongsam Kim, Ming-Chih Lai, Yunchang Seol
We use a computational technique based on the immersed boundary method to construct a four-roll mill device with which we can generate a broad spectrum of flow types from an extensional flow to a rotational one. We put a vesicle or a bubble in the constructed four-roll mill device to investigate their interaction with the surrounding fluid. The vesicle dynamics are determined by its bending rigidity, inextensibility, and hydrodynamical force, whereas the bubble dynamics is governed by the surface tension and the hydrodynamic interaction...
May 2017: Physical Review. E
https://www.readbyqxmd.com/read/28614744/effects-of-aeration-on-matrix-temperature-by-infrared-thermal-imager-and-computational-fluid-dynamics-during-sludge-bio-drying
#11
Dawei Yu, Min Yang, Lu Qi, Mengmeng Liu, Yawei Wang, Yuansong Wei
The effect of aeration on the pile matrix temperature was investigated using thermocouples and Infrared Thermal Imager (IRI) for temperature sensing, and Computational Fluid Dynamics (CFD) for modelling of temperature variation during aeration in a full-scale sludge biodrying plant. With aeration saving of 20%, the improved strategy speeded up biodrying from 21 days to 14 days, while achieving similar drying effect. A persistent thermocouple recorded the one-dimensional (1D) total temperature variation of all aeration strategies...
June 4, 2017: Water Research
https://www.readbyqxmd.com/read/28609457/robustness-of-common-hemodynamic-indicators-with-respect-to-numerical-resolution-in-38-middle-cerebral-artery-aneurysms
#12
Øyvind Evju, Jose M Pozo, Alejandro F Frangi, Kent-Andre Mardal
BACKGROUND: Using computational fluid dynamics (CFD) to compute the hemodynamics in cerebral aneurysms has received much attention in the last decade. The usability of these methods depends on the quality of the computations, highlighted in recent discussions. The purpose of this study is to investigate the convergence of common hemodynamic indicators with respect to numerical resolution. METHODS: 38 middle cerebral artery bifurcation aneurysms were studied at two different resolutions (one comparable to most studies, and one finer)...
2017: PloS One
https://www.readbyqxmd.com/read/28608962/image-based-computational-fluid-dynamics-in-the-lung-virtual-reality-or-new-clinical-practice
#13
REVIEW
Kelly S Burrowes, Jan De Backer, Haribalan Kumar
The development and implementation of personalized medicine is paramount to improving the efficiency and efficacy of patient care. In the respiratory system, function is largely dictated by the choreographed movement of air and blood to the gas exchange surface. The passage of air begins in the upper airways, either via the mouth or nose, and terminates at the alveolar interface, while blood flows from the heart to the alveoli and back again. Computational fluid dynamics (CFD) is a well-established tool for predicting fluid flows and pressure distributions within complex systems...
June 13, 2017: Wiley Interdisciplinary Reviews. Systems Biology and Medicine
https://www.readbyqxmd.com/read/28607933/optimal-branching-structure-of-fluidic-networks-with-permeable-walls
#14
Vinicius R Pepe, Luiz A O Rocha, Antonio F Miguel
Biological and engineering studies of Hess-Murray's law are focused on assemblies of tubes with impermeable walls. Blood vessels and airways have permeable walls to allow the exchange of fluid and other dissolved substances with tissues. Should Hess-Murray's law hold for bifurcating systems in which the walls of the vessels are permeable to fluid? This paper investigates the fluid flow in a porous-walled T-shaped assembly of vessels. Fluid flow in this branching flow structure is studied numerically to predict the configuration that provides greater access to the flow...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28603412/in-vitro-dose-comparison-of-respimat-%C3%A2-inhaler-with-dry-powder-inhalers-for-copd-maintenance-therapy
#15
Anna-Maria Ciciliani, Peter Langguth, Herbert Wachtel
BACKGROUND: Combining in vitro mouth-throat deposition measurements, cascade impactor data and computational fluid dynamics (CFD) simulations, four different inhalers were compared which are indicated for chronic obstructive pulmonary disease (COPD) treatment. METHODS: The Respimat inhaler, the Breezhaler, the Genuair, and the Ellipta were coupled to the idealized Alberta throat model. The modeled dose to the lung (mDTL) was collected downstream of the Alberta throat model using either a filter or a next generation impactor (NGI)...
2017: International Journal of Chronic Obstructive Pulmonary Disease
https://www.readbyqxmd.com/read/28600860/estimating-the-accuracy-of-a-reduced-order-model-for-the-calculation-of-fractional-flow-reserve-ffr
#16
Etienne Boileau, Sanjay Pant, Carl Roobottom, Igor Sazonov, Jingjing Deng, Xianghua Xie, Perumal Nithiarasu
Image-based non-invasive fractional flow reserve (FFR) is an emergent approach to determine the functional relevance of coronary stenoses. The present work aimed to determine the feasibility of using a method based on coronary computed tomography angiography (CCTA) and reduced-order models (0D-1D) for the evaluation of coronary stenoses. The reduced-order methodology (cFFRro ) was kept as simple as possible and did not include pressure drop or stenosis models. The geometry definition was incorporated into the physical model used to solve coronary flow and pressure...
June 9, 2017: International Journal for Numerical Methods in Biomedical Engineering
https://www.readbyqxmd.com/read/28599995/effects-of-vertical-glottal-duct-length-on-intraglottal-pressures-and-phonation-threshold-pressure-in-the-uniform-glottis
#17
Sheng Li, Ronald C Scherer, Lewis P Fulcher, Xianbo Wang, Lijun Qiu, Mingxi Wan, Supin Wang
According to Titze's 1988 derivations for phonation threshold pressure (PTP), there are a number of important variables that PTP depends upon. A primary one is the vertical glottal duct length T: PTP decreases if T is increased. Changing the length of T, however, may have a significant effect on other variables that PTP depends upon. This study examined the effects of lengthening the vertical uniform glottal duct on the transglottal and intraglottal pressures, and the derived transglottal pressure coefficients, for five glottal diameters (0...
June 6, 2017: Journal of Voice: Official Journal of the Voice Foundation
https://www.readbyqxmd.com/read/28598154/3d-printable-bioactivated-nanocellulose-alginate-hydrogels
#18
Jenni Leppiniemi, Panu Lahtinen, Antti Paajanen, Riitta Mahlberg, Sini Metsä-Kortelainen, Tatu Pinomaa, Heikki Pajari, Inger Vikholm-Lundin, Pekka Pursula, Vesa P Hytönen
We describe herein a nanocellulose-alginate hydrogel suitable for 3D printing. The composition of the hydrogel was optimized based on material characterization methods and 3D printing experiments, and its behavior during the printing process was studied using computational fluid dynamics simulations. The hydrogel was biofunctionalized by the covalent coupling of an enhanced avidin protein to the cellulose nanofibrils. Ionic cross-linking of the hydrogel using calcium ions improved the performance of the material...
June 23, 2017: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/28595860/diagnostic-performance-of-a-novel-method-for-fractional-flow-reserve-computed-from-noninvasive-computed-tomography-angiography-novel-flow-study
#19
Ju-Hyun Chung, Kyung Eun Lee, Chang-Wook Nam, Joon-Hyung Doh, Hyung Il Kim, Soon-Sung Kwon, Eun Bo Shim, Eun-Seok Shin
Coronary computed tomography angiography (CCTA)-derived fractional flow reserve from computed tomography (CT-FFR) may provide better diagnostic performance over CCTA alone, but the complexity of its method limits the use in clinical environment. The aim of the present study is to validate a newly developed vessel-length based computational fluid dynamics scheme for the computation of FFR based on CCTA data, compare them with invasively measured FFR, and evaluate its diagnostic performance with that of CCTA...
May 15, 2017: American Journal of Cardiology
https://www.readbyqxmd.com/read/28594889/use-of-the-fda-nozzle-model-to-illustrate-validation-techniques-in-computational-fluid-dynamics-cfd-simulations
#20
Prasanna Hariharan, Gavin A D'Souza, Marc Horner, Tina M Morrison, Richard A Malinauskas, Matthew R Myers
A "credible" computational fluid dynamics (CFD) model has the potential to provide a meaningful evaluation of safety in medical devices. One major challenge in establishing "model credibility" is to determine the required degree of similarity between the model and experimental results for the model to be considered sufficiently validated. This study proposes a "threshold-based" validation approach that provides a well-defined acceptance criteria, which is a function of how close the simulation and experimental results are to the safety threshold, for establishing the model validity...
2017: PloS One
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