Response of erythrocytes using 2-way FSI
 

Hi,

I am working on a 2-way Fluid structure interaction project related to RBC in capillaries.

I have designed a micro-scale shell RBC and a fluid medium which has diameter just above the dia of RBC.
In the transient structural analysis I have defined two fluid surface interfaces:
1. Exterior portion of RBC (blood interacting with exterior part) 2. Interior portion of RBC.(cytoplasm interacting with interior portion)

In the Fluent medium I have defined the walls, boundaries of capillary tube and cytoplasm (hollow portion of RBC) which are supposed to interact with with the solid RBC in Transient.

I have assumed that blood runs at x velocity and cytoplasm relatively at 0.97x velocity. Similarly, in transient I have 0.97x velocity, 9.7x displacement to Solid RBC

When I run the analysis by coupling both systems I receive error by doing so. But if I reduce the time step (0.0004) sec for 10 sub-steps ,velocity to 0.0000097x and displacement by 0.000097x solution runs smoothly.

Irrespective of correctness of result, Could anyone tell me why is that if i decrease the velocity, displacement and time steps there is result and why if i consider real time scenario this does not work?

Thanks