scholarly journals Numerical Analysis on the Effects of Saline Injection and Deformation for Radiofrequency Catheter Ablation

Electronics ◽  
2021 ◽  
Vol 10 (14) ◽  
pp. 1674
Author(s):  
Jin Woo Ahn ◽  
Young-Jin Kim
Keyword(s):  
Blood Flow ◽  
Catheter Ablation ◽  
Numerical Model ◽  
Radiofrequency Catheter Ablation ◽  
Numerical Models ◽  
Heart Tissue ◽  
Maximum Temperature ◽  
Saline Injection ◽  
Thermal Lesion ◽  
Advection Diffusion Equation

Radiofrequency catheter ablation is an interventional procedure used to treat arrhythmia. An electrode catheter that could inject saline has been developed to prevent steam pop on heart tissue during radiofrequency catheter ablation. Thus, we investigated to numerical model on the effect of saline injection and heart tissue’s deformation. In this study, the hyperelastic model was implemented to analyze heart tissue deformation due to the catheter’s contact force. Besides, the advection–diffusion equation was used to analyze the mixture between saline and blood. We developed the multiphysics model that predicts thermal lesions based on the deformation of the heart and mixing between saline and blood flow. The thermal lesion and the maximum temperature in the numerical model that considered mixing saline and blood were smaller than that of other numerical models that did not consider mixing. Therefore, we observed that the saline injection was affected by thermal lesion due to higher electrical conductivity than blood flow and injection at a lower temperature than the human body. The numerical model was researched that considering the deformation of the heart tissue and saline injection in radiofrequency catheter ablation affects the heart tissue’s thermal lesion and maximum temperature.

scholarly journals Numerical and Experimental Evaluation and Heat Transfer Characteristics of a Soft Magnetic Transformer Built from Laminated Steel Plates

Sensors ◽  
2021 ◽  
Vol 21 (23) ◽  
pp. 7939
Author(s):  
Eduardo Cano-Pleite ◽  
Andrés Barrado ◽  
Néstor Garcia-Hernando ◽  
Emilio Olías ◽  
Antonio Soria-Verdugo
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Numerical Model ◽  
Numerical Models ◽  
Subsequent Development ◽  
Steel Plates ◽  
Maximum Temperature ◽  
Heat Transfer Characteristics ◽  
Transfer Characteristics ◽  
Anisotropic Thermal Conductivity

The present work evaluates, both experimentally and numerically, the heat transfer characteristics of a 5 kW three-phase transformer built from laminated steel sheets. The transformer is operated at different powers, and its temperature distribution is monitored using 108 thermocouples. The experimental measurements are used firstly to determine the heat dissipated at the core and the windings of the transformer. This information is used as an input for a finite element numerical model, which evaluates the heat transfer characteristics of the transformer. The model proposed in this work simply solves the diffusion equation inside the transformer, accounting for the anisotropic thermal conductivity of the different components of the transformer, together with well-known correlations at its boundaries. The results reveal that the proposed numerical model can correctly reproduce the maximum temperature, the temperature distribution, and the time-evolution of the temperature at specific points of the transformer measured during the experimental campaign. These results are of great use for the subsequent development of transformers of the same type in lab-scale or industrial-scale size and reveal the applicability of simplified numerical models to accurately predict the heat transfer characteristics of this kind of transformers.

scholarly journals Study protocol of validating a numerical model to assess the blood flow in the circle of Willis

BMJ Open ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. e036404
Author(s):  
Yuanyuan Shen ◽  
Yanji Wei ◽  
Reinoud P H Bokkers ◽  
Maarten Uyttenboogaart ◽  
J Marc C van Dijk
Keyword(s):  
Blood Flow ◽  
Numerical Model ◽  
Study Protocol ◽  
Numerical Models ◽  
Medical Center ◽  
Pearson Correlation ◽  
Scientific Journal ◽  
Circle Of Willis ◽  
Patient Specific ◽  
Aneurysmal Subarachnoid Haemorrhage

IntroductionWe developed a zero-dimensional (0D) model to assess the patient-specific haemodynamics in the circle of Willis (CoW). Similar numerical models for simulating the cerebral blood flow (CBF) had only been validated qualitatively in healthy volunteers by magnetic resonance (MR) angiography and transcranial Doppler (TCD). This study aims to validate whether a numerical model can simulate patient-specific blood flow in the CoW under pathological conditions.Methods and analysisThis study is a diagnostic accuracy study. We aim to collect data from a previously performed prospective study that involved patients with aneurysmal subarachnoid haemorrhage (aSAH) receiving both TCD and brain Computerd Tomography angiography (CTA) at the same day. The cerebral flow velocities are calculated by the 0D model, based on the vessel diameters measured on the CTA of each patient. In this study, TCD is considered the gold standard for measuring flow velocity in the CoW. The agreement will be analysed using Pearson correlation coefficients.Ethics and disseminationThis study protocol has been approved by the Medical Ethics Review Board of the University Medical Center Groningen: METc2019/103. The results will be submitted to an international scientific journal for peer-reviewed publication.Trial registration numberNL8114.

Modelling the early age behaviour of a low heat concrete bulkhead sealing an underground tunnel

2000 ◽  
Vol 27 (1) ◽  
pp. 112-125 ◽  
Author(s):  
Olivier Didry ◽  
Malcolm N Gray ◽  
André Cournut ◽  
James Graham
Keyword(s):  
Numerical Model ◽  
Temperature Rise ◽  
Numerical Models ◽  
Autogenous Shrinkage ◽  
Heat Of Hydration ◽  
High Mass ◽  
Maximum Temperature ◽  
Early Age ◽  
Mass Concrete ◽  
Government Organizations

A major experiment - the tunnel sealing experiment, related to the disposal of heat generating radioactive wastes in geological formations and supported by government organizations from Japan, France, U.S.A., and Canada, is being carried out at the Underground Research Laboratory of Atomic Energy of Canada Limited in Manitoba, Canada. Through a systematic process, the results from the experiment will be used to validate numerical models for the early age behaviour of high mass concrete bulkheads. A numerical model, based on the CESAR-LCPC finite element code equipped with the modules TEXO and MEXO, has been developed and used to predict the behaviour of a concrete bulkhead which will be built as part of the experiment. The TEXO-based component of the model which describes temperature changes has been validated. A maximum temperature rise in the concrete of 19°C is calculated. This will occur about 4 days after the concrete is cast. The temperature rise is low. This arises from the use of a specially developed low cement content concrete. Despite uncertainties in the MEXO-based model, which is used to describe the chemo-mechanical behaviour of the system, results indicate that it is unlikely that the concrete will crack, but a gap of 0.5 mm or more will develop between the bulkhead and the rock. Water leakage around the bulkhead through this gap could be significant and measures to seal this gap are advised. The modelling results recorded here will be tested against measurements made in the experiment. Thus, the numerical model will be formally validated and bounds to its use will be defined. Key words: concrete, bulkhead, sealing, early age behaviour, heat of hydration, autogenous shrinkage, underground repository, modelling.

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