scholarly journals A multi-scale flow model for blood regulation in a realistic vascular system

2020 ◽  
Author(s):  
Ulin Nuha Abdul Qohar ◽  
Antonella Zanna Munthe-Kaas ◽  
Jan Martin Nordbotten ◽  
Erik Andreas Hanson
Keyword(s):  
Blood Flow ◽  
Blood Circulation ◽  
Numerical Models ◽  
Scale Model ◽  
Fluid Exchange ◽  
Desktop Computer ◽  
Multi Scale ◽  
Proposed Model ◽  
Porous Media Model ◽  
Capillary Bed

Abstract In the last decade, numerical models have been an increasingly important tool in medical science both for the fundamental understanding of the physiology of the human body as well as for diagnostics and personalized medicine. In this paper, a multi-scale model is developed for blood flow and regulation in a full vascular structure of an organ. We couple a 1D vascular graph model to represent blood flow in larger vessels and a porous media model to describe flow in smaller vessels and capillary bed. The vascular model is based on Poiseuille’s law, with pressure correction by elasticity and pressure drop estimation at vessels junctions. The porous capillary bed is modeled as a two compartments domain (arterial and venal) and Darcy’s law. The fluid exchange between the arterial and venal capillary bed compartments is defined as blood perfusion. The numerical experiments show that the proposed model for blood circulation: 1) is closely dependent on the structure and parameters of both the vascular vessels and of the capillary bed, and 2) it provides a realistic blood circulation in the organ. The advantage of the proposed model is that it is complex enough to capture the underlying physiology reliably, yet highly flexible as it offers the possibility of incorporating various local effects. Furthermore, the numerical implementation of the model is straightforward and allows for simulations on a regular desktop computer.

scholarly journals A nonlinear multi-scale model for blood circulation in a realistic vascular system

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Ulin Nuha A. Qohar ◽  
Antonella Zanna Munthe-Kaas ◽  
Jan Martin Nordbotten ◽  
Erik Andreas Hanson
Keyword(s):  
Blood Flow ◽  
Blood Circulation ◽  
Vascular System ◽  
Scale Model ◽  
Model Framework ◽  
Fluid Exchange ◽  
Multi Scale ◽  
Proposed Model ◽  
Porous Media Model ◽  
Capillary Bed

In the last decade, numerical models have become an increasingly important tool in biological and medical science. Numerical simulations contribute to a deeper understanding of physiology and are a powerful tool for better diagnostics and treatment. In this paper, a nonlinear multi-scale model framework is developed for blood flow distribution in the full vascular system of an organ. We couple a quasi one-dimensional vascular graph model to represent blood flow in larger vessels and a porous media model to describe flow in smaller vessels and capillary bed. The vascular model is based on Poiseuille’s Law, with pressure correction by elasticity and pressure drop estimation at vessels' junctions. The porous capillary bed is modelled as a two-compartment domain (artery and venous) using Darcy’s Law. The fluid exchange between the artery and venous capillary bed compartments is defined as blood perfusion. The numerical experiments show that the proposed model for blood circulation: (i) is closely dependent on the structure and parameters of both the larger vessels and of the capillary bed, and (ii) provides a realistic blood circulation in the organ. The advantage of the proposed model is that it is complex enough to reliably capture the main underlying physiological function, yet highly flexible as it offers the possibility of incorporating various local effects. Furthermore, the numerical implementation of the model is straightforward and allows for simulations on a regular desktop computer.

scholarly journals Three-dimensional multi-scale model of deformable platelets adhesion to vessel wall in blood flow

2014 ◽  
Vol 372 (2021) ◽  
pp. 20130380 ◽  
Author(s):  
Ziheng Wu ◽  
Zhiliang Xu ◽  
Oleg Kim ◽  
Mark Alber
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Vessel Wall ◽  
Platelet Adhesion ◽  
Three Dimensional ◽  
Clot Formation ◽  
Scale Model ◽  
Injury Site ◽  
Platelet Receptors ◽  
Multi Scale

When a blood vessel ruptures or gets inflamed, the human body responds by rapidly forming a clot to restrict the loss of blood. Platelets aggregation at the injury site of the blood vessel occurring via platelet–platelet adhesion, tethering and rolling on the injured endothelium is a critical initial step in blood clot formation. A novel three-dimensional multi-scale model is introduced and used in this paper to simulate receptor-mediated adhesion of deformable platelets at the site of vascular injury under different shear rates of blood flow. The novelty of the model is based on a new approach of coupling submodels at three biological scales crucial for the early clot formation: novel hybrid cell membrane submodel to represent physiological elastic properties of a platelet, stochastic receptor–ligand binding submodel to describe cell adhesion kinetics and lattice Boltzmann submodel for simulating blood flow. The model implementation on the GPU cluster significantly improved simulation performance. Predictive model simulations revealed that platelet deformation, interactions between platelets in the vicinity of the vessel wall as well as the number of functional GPIb α platelet receptors played significant roles in platelet adhesion to the injury site. Variation of the number of functional GPIb α platelet receptors as well as changes of platelet stiffness can represent effects of specific drugs reducing or enhancing platelet activity. Therefore, predictive simulations can improve the search for new drug targets and help to make treatment of thrombosis patient-specific.

scholarly journals Formulation and Stability Analysis of a Multi-Scale Modeling Approach for Simulation of Elastic Wave Propagation

2021 ◽  
pp. 2141010
Author(s):  
Siddhesh Raorane ◽  
Tadeusz Uhl ◽  
Pawel Packo
Keyword(s):  
Wave Propagation ◽  
Stability Analysis ◽  
Elastic Wave ◽  
Numerical Models ◽  
Practical Interest ◽  
Elastic Wave Propagation ◽  
Scale Model ◽  
Perfect Agreement ◽  
Multi Scale ◽  
Analytical Formulae

In this work, we report on the formulation and detailed stability analysis of a dynamic multi-scale scheme involving two different local computational strategies for modeling of elastic wave propagation. The coupled model involves the Local Interaction Simulation Approach and Cellular Automata for Elastodynamics, however the presented analysis approach is general and applies to other numerical techniques. This scheme is capable of coupling two numerical models with possibly dissimilar spatial discretization lengths and material properties, hence it is appealing for a multi-scale and/or multi-resolution analysis. The method developed in this paper employs an interface force–displacement coupling to yield the multi-scale model equations. It is shown that the governing equations contain a self-coupling term that affects the stability of the system, as it contributes to additional stiffness at the interface. Stability analysis is presented in terms of rotations of two vectors in [Formula: see text] space, where each vector represents individual model’s stability. Three model configurations of practical interest were investigated, analytical formulae derived and used to analyze stability. These analytical formulae were compared against results from numerical simulations and perfect agreement was observed.

An Object-Oriented Analysis of Complex Numerical Models

2014 ◽  
Vol 611-612 ◽  
pp. 1356-1363 ◽  
Author(s):  
Piotr Macioł ◽  
Romain Bureau ◽  
Christof Sommitsch
Keyword(s):  
Numerical Models ◽  
Object Oriented ◽  
Scale Model ◽  
Internal Variables ◽  
Object Oriented Design ◽  
Multi Scale ◽  
Advantages And Disadvantages ◽  
Single Scale ◽  
Scale Models ◽  
Modelling Methodology

Modelling the behaviour of metal alloys during their thermo-mechanical processing relies on the physical and mathematical description of numerous phenomena occurring in several space scales and evolving on different characteristic times. Although it is possible to develop complicated multi-scale models, it is often simpler to simulate each phenomenon separately in a single-scale model and link all the models together in a global structure responsible for their good interaction. Such a structure is relatively difficult to design. Both efficiency and flexibility must be well balanced, keeping in mind the character of scientific computing. In that context, the Agile Multiscale Modelling Methodology (AM3) has been developed in order to support the object-oriented designing of complex numerical models [. In this paper, the application of the AM3 for designing a model of the metal alloy behaviour is presented. The basis and some consequences of the application of the Object-Oriented design of a sub-models structure are investigated. The object-oriented (OO) design of a 3 internal variables model of the dislocations evolution is presented and compared to the procedural one. The main advantages and disadvantages of the OO design of numerical models are pointed out.

Application of Mathematical Models for Different Electroslag Remelting Processes

2017 ◽  
Vol 36 (4) ◽  
pp. 411-426
Author(s):  
Zhou Hua Jiang ◽  
Jia Yu ◽  
Fu Bin Liu ◽  
Xu Chen ◽  
Xin Geng
Keyword(s):  
Mathematical Models ◽  
Numerical Models ◽  
Electroslag Remelting ◽  
Scale Model ◽  
Multi Scale ◽  
Chemical Refining ◽  
Technology Process ◽  
Temperature Environment ◽  
The Relationship ◽  
Special Steels

AbstractThe electroslag remelting (ESR) process has been effectively applied to produce high grade special steels and super alloys based on the controllable solidification and chemical refining process. Due to the difficulties of precise measurements in a high temperature environment and the excessive expenses, mathematical models have been more and more attractive in terms of investigating the transport phenomena in ESR process. In this paper, the numerical models for different ESR processes made by our lab in last decade have been introduced. The first topic deals with traditional ESR process predicting the relationship between operating parameters and metallurgical parameters of interest. The second topic is concerning the new ESR technology process including ESR with current-conductive mould (CCM), ESR hollow ingot technology, electroslag casting with liquid metal(ESC LM), and so on. Finally, the numerical simulation of solidification microstructure with multi-scale model is presented, which reveals the formation mechanism of microstructure.

Strong Coupled Fluid-Structure Interaction Simulation of Cerebrovascular System Using Multi-Scale Model

2012 ◽  
Author(s):  
Kengo Katagiri ◽  
Absei Krdey ◽  
Sota Yamamoto ◽  
Marie Oshima
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Shear Stress ◽  
Subarachnoid Hemorrhage ◽  
Scale Model ◽  
Cerebrovascular Disorder ◽  
Structure Interaction ◽  
Multi Scale ◽  
Interaction Simulation ◽  
Cerebrovascular System

Cerebrovascular disorder such as subarachnoid hemorrhage is the number 3 cause of death in Japan [1]. Initiation and growth of those diseases depend on hemodynamic factors such as Wall Shear Stress (WSS) or blood pressure induced by blood flow [2]. Therefore the information on the magnitude and the distribution of WSS is important to predict the consequences.

scholarly journals Numerical Investigation of Centrifugal Blood Pump Cavitation Characteristics with Variable Speed

Processes ◽  
2020 ◽  
Vol 8 (3) ◽  
pp. 293 ◽  
Author(s):  
Teng Jing ◽  
Yujiao Cheng ◽  
Fangqun Wang ◽  
Wei Bao ◽  
Ling Zhou
Keyword(s):  
Blood Circulation ◽  
Aortic Pressure ◽  
Scale Model ◽  
Blood Pump ◽  
Centrifugal Blood Pump ◽  
Multi Scale ◽  
Ansys Cfx ◽  
Blood Pumps ◽  
Cavitation Intensity ◽  
Heart Blood

In this paper, the cavitation characteristics of centrifugal blood pumps under variable speeds were studied by using ANSYS-CFX and MATLAB software. The study proposed a multi-scale model of the “centrifugal blood pump—left heart blood circulation”, and analyzed the cavitation characteristics of the centrifugal blood pump. The results showed that the cavitation in the impeller first appeared near the hub at the inlet of the impeller. As the inlet pressure decreased, the cavitation gradually strengthened and the bubbles gradually developed in the outlet of the impeller. The cavitation intensity increased with the increase of impeller speed. The curve of the variable speeds of the centrifugal blood pump in the optimal auxiliary state was obtained, which could effectively improve the aortic pressure and flow. In variable speeds, due to the high aortic flow and pressure during the ejection period, the sharp increases in speeds led to cavitation. The results could provide a guidance for the optimal design of the centrifugal blood pump.

scholarly journals A Heterogeneous Multi-scale Model for Blood Flow

2020 ◽  
pp. 403-409
Author(s):  
Benjamin Czaja ◽  
Gábor Závodszky ◽  
Alfons Hoekstra
Keyword(s):  
Blood Flow ◽  
Scale Model ◽  
Multi Scale

scholarly journals Micromechanical modeling of ductile fracture of human humerus

2020 ◽  
Vol 14 (2) ◽  
pp. 6952-6960
Author(s):  
J. Rahmoun ◽  
H. Naceur ◽  
P. Drazetic ◽  
C. Fontaine
Keyword(s):  
Ductile Fracture ◽  
Impact Load ◽  
Damage Model ◽  
Scale Model ◽  
Micromechanical Modeling ◽  
Formulation Development ◽  
Multi Scale ◽  
Proposed Model ◽  
Explicit Dynamic ◽  
Development And Validation

This paper deals with the formulation, development and validation of a newly developed micromechanical-based model for the modeling of the nonlinear ductile fracture of human humerus. The originality of the present works concerns the coupling between the micromechanical formulation based on the Mori-Tanaka homogenization scheme for cylindrical voids and the Marigo nonlinear ductile damage model based on the porosity growth. The proposed model was implemented as a User Material UMAT within the explicit dynamic software LS-DYNA and validated by numerical and experimental analysis conducted by a drop tower impact of human humerus. The outcome of the proposed multi-scale model appears to correctly predict the general trends observed experimentally via the good estimation of the ultimate impact load and the fracture patterns of the human humerus.

Multi-scale characterization and modelling of damage evolution in nuclear Gilsocarbon graphite

2015 ◽  
Vol 1809 ◽  
pp. 1-6 ◽  
Author(s):  
Dong Liu ◽  
Peter Heard ◽  
Branko Šavija ◽  
Gillian Smith ◽  
Erik Schlangen ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Testing ◽  
Numerical Models ◽  
Ion Beam ◽  
Microstructural Characterization ◽  
Scale Model ◽  
Small Scale ◽  
Length Scale ◽  
Multi Scale ◽  
Scale Characterization

ABSTRACTIn the present work, the microstructure and mechanical properties of Gilsocarbon graphite have been characterized over a range of length-scales. Optical imaging, combined with 3D X-ray computed tomography and 3D high-resolution tomography based on focus ion beam milling has been adopted for microstructural characterization. A range of small-scale mechanical testing approaches are applied including an in situ micro-cantilever technique based in a Dualbeam workstation. It was found that pores ranging in size from nanometers to tens of micrometers in diameter are present which modify the deformation and fracture characteristics of the material. This multi-scale mechanical testing approach revealed the significant change of mechanical properties, for example flexural strength, of this graphite over the length-scale from a micrometer to tens of centimeters. Such differences emphasize why input parameters to numerical models have to be undertaken at the appropriate length-scale to allow predictions of the deformation, fracture and the stochastic features of the strength of the graphite with the required confidence. Finally, the results from a multi-scale model demonstrated that these data derived from the micro-scale tests can be extrapolated, with high confidence, to large components with realistic dimensions.

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