Figure 5 - uploaded by Lilit Axner
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4: Velocity profile in lattice unites of carotid artery with severe stenosis after bypass placement every 100 time-steps during one period from bypass(top) and stenosis(bottom) sides. Here B is the region where we look into velocity profiles in details in Figs. 5.5 and 5.6
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A new relaxed multi-direct-forcing immersed boundary-cascaded lattice Boltzmann method (MDF IB-CLBM) is proposed in this paper. This new technique improves the efficiency and accuracy of implementing no-slip boundaries on a single graphics processing unit (GPU). The traditional MDF-IBM method essentially solves a linear system iteratively with a re...
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The transport of platelets in blood is commonly assumed to obey an advection-diffusion equation with a diffusion constant given by the so-called Zydney-Colton theory. Here we reconsider this hypothesis based on experimental observations and numerical simulations including a fully resolved suspension of red blood cells and platelets subject to a she...
We employ a free energy lattice Boltzmann method to study the dynamics of a ternary fluid system consisting of a liquid drop driven by a body force across a regularly textured substrate, infused by a lubricating liquid. We focus on the case of partial wetting lubricants and observe a rich interplay between contact line pinning and viscous dissipati...
Citations
... Pudiera haber sido obtenido, a través de dinámica Computacional de Fluidos (CFD, por sus siglas en Inglés); con las nuevas tecnologías para la obtención de áreas vasculares con fines de modelaje, recurriéndose por tanto a métodos computacionales de aproximación bajo computación paralela, pero al momento ello es solamente aplicable a segmentos de longitud muy cortos del árbol circulatorio; por tanto, es impensable de haberse usado como apoyo del paradigma al comienzo citado, pues por demás constituye el último estado del arte en modelaje cardio-vascular preoperatorio para colocación de bypass y stents y el paradigma precitado es de vieja data (Zaráte, 2004;Axner, 2010). ...
Para este estudio se utilizaron dos machos de raza mestiza de 30 y 28 Kg de peso vivo respectivamente. Como hipertensor se utilizó Noradrenalina a dosis de 0,02 mg/kg. Se instaló un dispositivo biofísico en la arteria femoral. Se diseñaron dos Pruebas: En la prueba A se conectó el dispositivo pinzado antes de aplicar el primer bolo de Noradrenalina y en la prueba B se conectó el dispositivo pinzado después de aplicar el primer bolo de Noradrenalina. Antes y después de la instalación del dispositivo antihipertensor en la arteria femoral se controló la (PAM) en condiciones basales por medio de tensiómetro de regulación automática tipo manguito. En la prueba A se observó que al aplicar la Noradrenalina con el dispositivo instalado cerrado, la (PAM) subió a los 2 minutos a 156 -157 mmHg; y a los 8 minutos, bajó a parámetros normales: 60 mmHg. Luego se abrió el dispositivo para que fluyera la sangre y se aplicó el segundo bolo, se observó que a los 7 minutos alcanzó un máximo de 101 mmHg y a los 3 minutos bajó a parámetros normales: 66 mmHg.. En la prueba B, se observó que al aplicar la Noradrenalina sin el dispositivo instalado, la (PAM) subió a los 5 minutos a un máximo de 271 mmHg; y a los 30 minutos, bajó a parámetros normales: 87 mmHg. Luego se conectó el dispositivo para que fluyera la sangre y se aplicó el segundo bolo, se observó que a los 10 minutos alcanzó un máximo de: 204 mmHg y a los 10 minutos bajó a parámetros normales: 77 mmHg.. Por lo observado se concluye que el dispositivo extracorpóreo permite retrasar un evento de hipertensión en un 100% en función del tiempo, disminuir un pico de hipertensión en un 33% y a su vez acortar el tiempo hipertensor, reduciéndose la estabilización del paciente en 2/3, permitiendo así mejorar la respuesta del organismo ante un evento de HASAS.
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... A few studies within the medical domain are of special relevance to this work. These include a performance analysis of a blood-flow LB solver using a range of sparse and non-sparse geometries [15] and a performance prediction model for lattice-Boltzmann solvers [16]. This performance prediction model can be applied largely to our HemeLB application, although HemeLB uses a different decomposition technique and performs real-time rendering and visualization tasks during the LB simulations. ...
... To model the performance of the core LB simulator code we propose a time-complexity model which is loosely based on [16] but largely simplified. We use a range of parameters which we derived in Section 3.1. ...
We investigate the performance of the HemeLB lattice-Boltzmann simulator for
cerebrovascular bloodflow, intended to provide timely and clinically relevant
assistance to neurosurgeons. HemeLB is optimized for sparse geometries and
supports interactive use, and scales well to 32,768 cores for problems with ~81
million lattice sites. We obtain a maximum performance of 29.5 billion site
updates per second, and show only an 11% slowdown for highly sparse problems
(5% fluid fraction). We present steering and visualization performance
measurements and provide a model which allows users to predict the performance,
thereby determining how to run simulations with maximum accuracy within time
constraints.
Tortuosity is an important parameter for characterizing transport properties within porous materials and is of interest in a broad range of fields, such as energy storage and conversion materials. One of the parameters that impacts the tortuosity value is the geometry of the solid phase which, in this study, is considered as stochastically-placed rectangular particles. Through lattice Boltzmann modelling (LBM), we determined the impact of particle aspect ratio on the intrinsic tortuosity–porosity relationships of two-dimensional porous media composed of rectangular particles. These relationships were isolated for materials with grain (particle) aspect ratios of ∈ {1, 2, 3} and porosities from [0.55 – 0.95]. We determined that a minimum of 6, 8 and 10 stochastic simulations, respectively, were required to calculate these average tortuosity values in laminar flow (\( Re \ll 1 \)). This novel application of the LBM to study the effects of porosity and aspect ratio of rectangular grains on tortuosity can be used in the tailoring of materials for clean energy.
We compare the Lattice BGK, the Multiple Relaxation Times and the Entropic Lattice Boltzmann Methods for time harmonic flows. We measure the stability, speed and accuracy of the three models for Reynolds and Womersley numbers that are representative for human arteries.
The Lattice BGK shows predictable stability and is the fastest method in terms of lattice node updates per second. The Multiple Relaxation Times LBM shows erratic stability which depends strongly on the relaxation times set chosen and is slightly slower. The Entropic LBM gives the best stability at the price of fewer lattice node updates per second.
A parameter constraint optimization technique is used to determine which is the fastest model given a certain preset accuracy. It is found that the Lattice BGK performs best at most arterial flows, except for the high Reynolds number flow in the aorta, where the Entropic LBM is the fastest method due to its better stability. However we also conclude that the Entropic LBM with velocity/pressure inlet/outlet conditions shows much worse performance.
