Unlike ordinary elastic solids and liquids, complex fluids exhibit several strange behaviors that depend primarily on the underlying structures that make these fluids. Indeed, many complex fluids consist of microscopic entities (such as rigid or deformable particles, biological cells, macromolecules etc. ..) which are suspended in the liquid, and which individuals and collective behavior impact on all the rheological properties of the fluid at a macro scale. It is this feedback from the micro scale to macro scale that gives this complex behavior in these fluids and continues to pose a formidable challenge to theoretical modeling. Typical examples of these complex fluids are, for example suspensions (rigid particles suspended in a Newtonian fluid), emulsions (droplets suspended in a Newtonian fluid), blood (red blood cells suspended in plasma), and so after. Complex fluids are the rule in the industrial and biological worlds, conferring on it a significant interest in various fields ranging from fundamental technological. A major challenge in complex fluids lies in the understanding of (i) the interaction fluid / particle level structure and (ii) the spatiotemporal organization of entities (ie their collective behavior training bands …) that make up the complex fluid.

bloodrheol1-fe20d

Red blood cell cytoskeleton

 

bloodrheol2-3d963

Bi-concave shape of a red blood cell

In recent years, we have developed numerical methods, models and software platform (Feel ++) for the numerical simulation of blood rheology in the vascular system: The purpose of this project is to simulate suspensions a large number of vesicles – acting as models for the blood-cells. It has indeed been shown that there are several similarities between the vesicles and red blood cells (RBCs) in particular from the mechanical point of view. For example, as the GR, the shear flow under vesicles have different dynamic: tank threading and tumbling. In 5 years, we expect to be able to simulate tens of deformable vesicles (GR) in the 3D flow in arteries with moving borders hundreds of processors in the 10 years hundreds of deformable vesicles 3D flow in arteries with moving boundaries. The scope is to study blood flow pulsating in medium and small arteries. In this context large displacements of the membrane (more than 10% of the radius) of the arteries coexist with the containment of blood flow.

Our job now is to build four ingredients:

  • High order methods of discretization in space, time and geometry applied to flows in the mobile domain,
  • leveset of methods and methods of fictitious domain,
  • Domain decomposition methods and strategies parallel resolution
  • Effective use of HPC architectures

Funders

This work is in collaboration with physicists from Grenoble (LIPHY) and is funded at present by the Ministry of Higher Education and Research, the Rhône-Alpes Region (2009-2012), the ANR HAMM (2010-2014) and the ANR VIVABRAIN (2013-2017)

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