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 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 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 On-lattice agent-based simulation of populations of cells within the open-source Chaste framework

2013 ◽  
Vol 3 (2) ◽  
pp. 20120081 ◽  
Author(s):  
Grazziela P. Figueredo ◽  
Tanvi V. Joshi ◽  
James M. Osborne ◽  
Helen M. Byrne ◽  
Markus R. Owen
Keyword(s):  
Tumour Growth ◽  
Current System ◽  
Reaction Diffusion ◽  
Multiple Scale ◽  
Reaction Diffusion Equations ◽  
Scale Model ◽  
Low Oxygen ◽  
Model Framework ◽  
Agent Based ◽  
Multi Scale

Over the years, agent-based models have been developed that combine cell division and reinforced random walks of cells on a regular lattice, reaction–diffusion equations for nutrients and growth factors; and ordinary differential equations for the subcellular networks regulating the cell cycle. When linked to a vascular layer, this multiple scale model framework has been applied to tumour growth and therapy. Here, we report on the creation of an agent-based multi-scale environment amalgamating the characteristics of these models within a Virtual Physiological Human (VPH) Exemplar Project. This project enables reuse, integration, expansion and sharing of the model and relevant data. The agent-based and reaction–diffusion parts of the multi-scale model have been implemented and are available for download as part of the latest public release of Chaste (Cancer, Heart and Soft Tissue Environment; http://www.cs.ox.ac.uk/chaste/), part of the VPH Toolkit (http://toolkit.vph-noe.eu/). The environment functionalities are verified against the original models, in addition to extra validation of all aspects of the code. In this work, we present the details of the implementation of the agent-based environment, including the system description, the conceptual model, the development of the simulation model and the processes of verification and validation of the simulation results. We explore the potential use of the environment by presenting exemplar applications of the ‘what if’ scenarios that can easily be studied in the environment. These examples relate to tumour growth, cellular competition for resources and tumour responses to hypoxia (low oxygen levels). We conclude our work by summarizing the future steps for the expansion of the current system.

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.

A multi-scale model of real contact area for linear guideway based on the fractal theory

2021 ◽  
pp. 095440622098336
Author(s):  
Xinxin Li ◽  
Zhimin Li ◽  
Sun Jin ◽  
Jichang Zhang
Keyword(s):  
Contact Area ◽  
Manufacturing Industry ◽  
Fractal Theory ◽  
Scale Model ◽  
Design Stage ◽  
Real Contact Area ◽  
The Real ◽  
Multi Scale ◽  
Real Contact ◽  
Proposed Model

High precision, efficiency and reliability are the unremitting pursuits of machinery manufacturing industry. As one of the pivotal function parts of high-end NC machine tool, precise linear guideway determines the machining precision and operation performance. Accurate evaluation and prediction of surface topography are the crucial effects on the matching performance of linear guideway. In this paper, the real contact area is regarded as a key parameter, a multi-scale method with the fractal theory is proposed. First, the contact area of a single asperity was obtained with Hertz contact theory. Afterwards, the contact area between rough surfaces was deduced by the fractal theory. Finally, using the proposed multi-scale contact mechanics model, the real contact area between rough plane and cylinder was obtained by integral solution. Compared with the former fractal model and GW model, the proposed model on the real contact area calculation of linear guideway is more accurate and comprehensive. The effect factors of load, fractal parameter and friction were discussed, the increasing rate of real contact area of smoother surface is greater as load increases. The proposed model may provide practical guidance for assembly accuracy and surface quality requirements at design stage.

Bestimmung des zerebralen Blutflusses mittels des 81 Rb/81 mKr-Generatorsystems

1990 ◽  
Vol 29 (01) ◽  
pp. 7-12 ◽  
Author(s):  
J. Bialy ◽  
F.-J. Hans ◽  
E. Oberhausen ◽  
W.J. Peters ◽  
M. Schmitt ◽  
...  
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Blood Circulation ◽  
Semiconductor Device ◽  
Animal Experiments ◽  
Initial Value ◽  
Brain Arteries ◽  
Sufficient Concentration ◽  
Static Quantity

A method is being developed which not only measures cerebral blood flow as a static quantity but also its changes with time. For that purpose a semiconductor device ascertains the proportion of intracerebral81 Rb and 81mKr activities. By opening the haemato-encephalic barrier in animal experiments a sufficient concentration of intracerebral81 Rb could be attained and the modified blood circulation after step-wise ligature of all brain arteries brought into relation to the corresponding Rb/Kr quotient. Over the range from undisturbed to completely interrupted cerebral blood flow this quotient varied up to 25% of its initial value.

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