Fluid–Structure Interaction and Non-Fourier Effects in Coupled Electro-Thermo-Mechanical Models for Cardiac Ablation

In this study, a fully coupled electro-thermo-mechanical model of radiofrequency (RF)-assisted cardiac ablation has been developed, incorporating fluid–structure interaction, thermal relaxation time effects and porous media approach. A non-Fourier based bio-heat transfer model has been used for predicting the temperature distribution and ablation zone during the cardiac ablation. The blood has been modeled as a Newtonian fluid and the velocity fields are obtained utilizing the Navier–Stokes equations. The thermal stresses induced due to the heating of the cardiac tissue have also been accounted. Parametric studies have been conducted to investigate the effect of cardiac tissue porosity, thermal relaxation time effects, electrode insertion depths and orientations on the treatment outcomes of the cardiac ablation. The results are presented in terms of predicted temperature distributions and ablation volumes for different cases of interest utilizing a finite element based COMSOL Multiphysics software. It has been found that electrode insertion depth and orientation has a significant effect on the treatment outcomes of cardiac ablation. Further, porosity of cardiac tissue also plays an important role in the prediction of temperature distribution and ablation volume during RF-assisted cardiac ablation. Moreover, thermal relaxation times only affect the treatment outcomes for shorter treatment times of less than 30 s.

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A method combined immersed boundary with multi-relaxation-time lattice Boltzmann flux solver for fluid-structure interaction

Acta Physica Sinica ◽

10.7498/aps.66.224702 ◽

2017 ◽

Vol 66 (22) ◽

pp. 224702

Author(s):

Wu Xiao-Di ◽

Liu Hua-Ping ◽

Chen Fu

Keyword(s):

Relaxation Time ◽

Lattice Boltzmann ◽

Fluid Structure Interaction ◽

Immersed Boundary ◽

Fluid Structure ◽

Structure Interaction

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Computational Modeling of Cardiac Ablation Incorporating Electrothermomechanical Interactions

Journal of Engineering and Science in Medical Diagnostics and Therapy ◽

10.1115/1.4048536 ◽

2020 ◽

Vol 3 (4) ◽

Author(s):

Sundeep Singh ◽

Roderick Melnik

Keyword(s):

Blood Flow ◽

Computational Modeling ◽

Radio Frequency ◽

Treatment Outcomes ◽

Cardiac Tissue ◽

Numerical Study ◽

Cardiac Ablation ◽

Cardiac Chamber ◽

Ablation Volume ◽

Fully Coupled

Abstract The application of radio frequency ablation (RFA) has been widely explored in treating various types of cardiac arrhythmias. Computational modeling provides a safe and viable alternative to ex vivo and in vivo experimental studies for quantifying the effects of different variables efficiently and reliably, apart from providing a priori estimates of the ablation volume attained during cardiac ablation procedures. In this contribution, we report a fully coupled electrothermomechanical model for a more accurate prediction of the treatment outcomes during the radio frequency cardiac ablation. A numerical model comprising of cardiac tissue and the cardiac chamber has been developed in which an electrode has been inserted perpendicular to the cardiac tissue to simulate actual clinical procedures. Temperature-dependent heat capacity, electrical and thermal conductivities, and blood perfusion rate have been considered to model more realistic scenarios. The effects of blood flow and contact force of the electrode tip on the treatment outcomes of a fully coupled model of RFA have been systematically investigated. The numerical study demonstrates that the predicted ablation volume of RFA is significantly dependent on the blood flow rate in the cardiac chamber and also on the tissue deformation induced due to electrode insertion depth of 1.5 mm or higher.

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The hydrodynamic FORCE of fluid–structure interaction interface in lattice Boltzmann simulations

International Journal of Modern Physics B ◽

10.1142/s0217979220400858 ◽

2020 ◽

Vol 34 (14n16) ◽

pp. 2040085

Author(s):

Ying Tong ◽

Jian Xia

Keyword(s):

Relaxation Time ◽

Lattice Boltzmann ◽

Numerical Solutions ◽

Hydrodynamic Force ◽

Critical Role ◽

Fluid Structure Interaction ◽

Momentum Exchange ◽

Fluid Structure ◽

Structure Interaction ◽

Lattice Resolution

The hydrodynamic force (HF) evaluation plays a critical role in the numerical simulation of fluid–structure interaction (FSI). By directly using the distribution functions of lattice Boltzmann equation (LBE) to evaluate the HF, the momentum exchange algorithm (MEA) has excellent features. Particularly, it is independent of boundary geometry and avoids integration on the complex boundary. In this work, the HF of lattice Boltzmann simulation (LBS) is evaluated by using the MEA. We conduct a comparative study to evaluate two lattice Boltzmann models for constructing the flow solvers, including the LBE with single-relaxation-time (SRT) and multiple-relaxation-time (MRT) collision operators. The second-order boundary condition schemes are used to address the curve boundary. The test case of flow past a cylinder asymmetrically placed in a channel is simulated. Comparing the numerical solutions of Lattice Boltzmann method (LBM) with those of Navier–Stokes equations in the literature, the influence of collision relaxation model, boundary conditions and lattice resolution is investigated. The results demonstrate that the MRT-LB improves the numerical stability of the LBM and the accuracy of HF.

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