An Elasto-visco-plastic Model of Cell Aggregates

Concentrated cell suspensions exhibit different mechanical behavior depending on the me-chanical stress or deformation they undergo. These systems have a mixed rheological nature: cells behave elastically or viscoelastically, they can adhere to each other whereas the carrying fluid is usually Newtonian. We report here on a new elasto–visco–plastic model which is able to describe the mechanical properties of a concentrated cell suspension or aggregate. It is based on the idea that the rearrangement of adhesion bonds during the deformation of the aggregate is related to the existence of a yield stress in the macroscopic constitutive equation. We compare the predictions of this new model with three experimental situations: steady shear rate, oscillatory shearing tests as well as relaxation after application of a prescribed deformation. All of these experiments are shown to agree with the predictions of the model