DIRECT SIMULATIONS OF CELLS MOTIONS

AND DEFORMATIONS IN FLOW

Quan Jin

Advisor: Dr. Pushpendra Singh

The motion and deformation of cells, especially leukocytes, in pressure driven flow in parallel plate channel, with and without the adhesion force acting between the leukocytes and the channel wall, is studied using the three dimensional direct numerical simulation.

Two composite models, composite-drop model and drop-rigid particle model, are used to describe the rheology of leukocyte which is a multi-component system composed of a membrane, cytoplasm, and nucleus. An equilibrium location is found for freely suspended leukocyte in pressure driven flows in the channel. This position is shown to depend on the ratio of the cell and plasma viscosities.

The adhesion force is computed using two adhesion models. In the first model the adhesion force is given by a potential in which is a function of the distance between the cell and the adhesive wall. In the second model the adhesion force is given by the Bell’s kinetic adhesion model. The behavior of the kinetic model is analyzed and used to simulate the deformation of leukocytes on a layer of endothelial cells. The numerical code is based on a finite element method and uses the level-set method to track the cell membrane position. The cytoplasm is modeled by the Bingham model and also as a viscoelastic liquid.