International Journal for Numerical Methods in Biomedical Engineering

In this paper, we develop a thermodynamically consistent four-species model of tumor growth on the basis of the continuum theory of mixtures. Unique to this model is the incorporation of nutrient within the mixture as opposed to being modeled with an auxiliary reaction-diffusion equation. The formulation involves systems of highly nonlinear partial differential equations of surface effects through diffuse-interface models. A mixed finite element spatial discretization is developed and implemented to provide numerical results demonstrating the range of solutions this model can produce.

The present work proposes a multiscale/multiphysics model for the understanding of the molecular mechanism of proton transport in transmembrane proteins involving continuum, atomic, and quantum descriptions, assisted with the evolution, formation, and visualization of membrane channel surfaces. We describe proton dynamics quantum mechanically via a new density functional theory based on the Boltzmann statistics, while implicitly model numerous solvent molecules as a dielectric continuum to reduce the number of degrees of freedom.

We propose a finite element approximation to solve the coupling between the propagation of electrical potential and large deformations of the cardiac tissue, based on the active strain assumption. A new phenomenological model for the mechanical activation is introduced and various numerical tests performed with a parallel finite element code illustrate that the proposed method can capture some important features of the excitation-contraction mechanism.

In this paper, a parallel-coupled electromechanical model of the heart is presented and assessed. The parallel-coupled model is thoroughly discussed, with scalability proven up to hundreds of cores. This work focuses on the mechanical part including the constitutive model, the numerical scheme and the coupling strategy.

In the present work, we develop a three-dimensional isotropic finite-strain damage model for abdominal aortic aneurysm (AAA) wall that considers both the characteristic softening of the material caused by damage and the spatial variation of the material properties. A strain energy function is formulated that accounts for a hyperelastic, slightly compressible, isotropic material behavior during the elastic phase, whereas the damage process only contributes to the material response when the elastic limit of the AAA wall is exceeded. Material and damage parameters are obtained by fitting the strain energy function to the experimental data obtained by uniaxial tensile tests of freshly harvested AAA wall samples.

We analyse the influence of blood viscosity and stenosis on the aorta loadings during shock.

This paper presents an anatomically realistic three-dimensional finite element model of the tongue and surrounding soft tissues with potential application to the study of sleep apnoea. An active Hill three-element muscle model was used to represent the muscular tissue of the tongue, and a genetic algorithm-based neural control model is developed to control movement. It is demonstrated that the neural model is able to control the position of the tongue and produce a physiologically realistic response for the genioglossus under breathing-induced loading conditions.

An overview of surface and volume mesh generation techniques for creating valid meshes to carry out biomedical flows is provided. The methods presented are designed for robust numerical modelling of biofluid flow through subject-specific geometries. The applications of interest are haemodynamics in blood vessels and air flow in upper human respiratory tract. The methods described are designed to minimize distortion to a given domain boundary. They are also designed to generate a triangular surface mesh first and then volume mesh (tetrahedrons) with high quality surface and volume elements.

The anatomical axis of the femur (FAA) can be automatically extracted from a 3D image by fitting hyperboloids to the diaphysis. The orientation and entry point of a 200-mm long intramedullary rod (FIR), which is used for prosthesis positioning during total knee arthroplasty, can then be computed by fitting a line to the FAA. Precise results are obtained from images that are reduced to 60% of the length, meaning that partial scans can be used for preoperative planning.

Non-rigid registration is used to represent variations in human skull shape. Subsequent finite element analyses quantify stresses caused by mastication, and differences in stresses caused by skull shape variation. The effect of mapping uncertainty on these stress differences is also quantified.