A pilot study of a phenomenological model of adipogenesis in maturing adipocytes using Cahn–Hilliard theory

We consider the accumulation and formation of lipid droplets in an adipocyte cell. The process incorporates adipose nucleation (adipogenesis) and growth. At later stages, there will be merging of droplets and growth of larger droplets at the expense of the smaller droplets, which will essentially undergo lipolysis. The process is modeled by the use of the Cahn–Hilliard equation, which is mass-conserving and allows the formation of secondary phases in the context of spinodal decomposition. The volume of fluid (VOF) method is used to determine the total area that is occupied by the lipids in a given cross section. Further, we present an algorithm, applicable to all kinds of grids (structured or unstructured) in two spatial dimensions, to count the number of lipid droplets and the portion of the domain of computation that is occupied by the lipid droplets as a function of time during the process. The results are preliminary and are validated from a qualitative point using experiments carried out on cell cultures. It turns out that the Cahn–Hilliard theory can model many of the features during adipogenesis qualitatively

On the numerical modelling of ductile damage with an implicit gradient-enhanced formulation

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Strongly nonlocal gradient-enhanced finite strain elastoplasticity

This paper presents a gradient plasticity formulation developed in a strongly non-local format and applicable to ductile failure for finite strain plasticity. The obtained formulation is an extension of a framework proposed by Simo (Computer Methods in Applied Mechanics and Engineering 1988; 66: 199) into the softening and localization regime. The presented model inherits the well-established regularization properties of its strongly non-local enrichment and leads to an implicit computational scheme with a consistent tangent operator. Numerical examples are given which illustrate the strongly non-local character of the formulation, the influence of the type of intrinsic length scale considered, as well as several topics on plastic failure initiation and evolution into the geometrically non-linear regime

Generalized continua and phase-field models : application to crystal plasticity

International audienceThree continuum field theories are presented that account for the size-dependent behaviour of materials. The micromorphic medium is endowed with microdeformation degrees of freedom that describe the rotation and distortion of a triad of microstructural directions, like crystallographic lattice directions. It is a very general framework that can be specialized to strain gradient plasticity theory dedicated to the modelling of plastic events in metals and alloys. Both frameworks are developed here in the special case of crystal plasticity as a complete example of transition from micro-physical phenomena to continuum macro-modelling. Finally the phase field method is introduced in this landscape as a continuum modelling approach to the motion of phase boundaries and interfaces driven by thermodynamics and mechanics