Each time a neutrophil (cell) pass through the human lungs, it typically crosses over 50 capillary segments. The transit time of the neutrophil depends on its deformability, surface tension, pressure drop across the capillary, and the geometry of the capillary.
The ADINA-FSI program is used to simulate the passage of a neutrophil through a pulmonary capillary segment. The capillary has a constriction with a diameter smaller than that of the neutrophil and a pressure difference exists between both ends of the capillary, which is the driving force responsible for the motion of the neutrophil.
This is a fully coupled fluid-structure interaction problem. The plasma in the capillary is modeled as a Newtonian fluid with an Arbitrary Lagrangian Eulerian (ALE) mesh in order to ensure that the dense region of the fluid mesh moves appropriately with the neutrophil. The neutrophil is modeled as a viscoelastic Maxwell solid undergoing large displacements and large strains. A surface tension boundary is applied to the neutrophil and contact is enforced between its boundaries and the capillary walls.
Reference
- M. Bathe, A. Shirai, C.M. Doerschuk, and R.D. Kamm, “Neutrophil transit times through pulmonary capillaries: The effects of capillary geometry and fMLP-stimulation”, Biophysical Journal, 83:1917–1933, 2002
Courtesy of M. Bathe, A. Shirai, R.D. Kamm, (Massachusetts Institute of Technology, USA) and C.M. Doerschuk (Rainbow Babies and Children’s Hospital and Case Western Reserve University, USA)
