1. Numerical Study of Expiratory Flow in the case of mjaor upper airway obstruction with fluid-structure interaction Dr. Zishun LIU and George XU

2. Objective To explore the fluid-structure interaction methodology (available in ADINA) to gain insight into the obstructive sleep apnea syndrome (OSAS) Coupling the structure module (ADINA-A) with the fluid dynamics module (ADINA-F)

3. Numerical procedure NASTRAN Structure model (geom+mesh) Fluid model (geom+mesh) ADINA ADINA-A (setup) ADINA-F (setup) (Iterative) ADINA ADINA (post-processing) ** Direct coupling approaching will be explored comparatively in future)

4. Testing Case Geometrial configuration D=49mm, d=25mm hc = 1.84mm Running condition: Pext = 200Pa, Pout = 0 Pa Pin = 0 - 200 Pa hc Pext Pout Pin

5. Model Settings Mesh for structure model Boundary conditions in structure model FSI interface Mesh for CFD model (partial view) Boundary conditions in CFD model

6. Preliminary Results Evolution of maximum vertical displacement (downwards) Y-displacement (downwards) Time steps

7. Preliminary Results Evolution of displacement on the longitudinal vertical cutting plane through shell centre (magnified view) t = 0 t = 1 t = 10 t = 20 t = 30 t = 50

8. Preliminary Results Evolution of velocity field t =0 t = 1 t = 10 t = 20 t = 30 t = 50

9. Conclusion The main objective here is to test the feasibility in using ADINA to deal with the FSI problem of concern. The preliminary effort implies that ADINA can be successfully adopted in the FSI study. Uncertainties in the preliminary model lie in: Relatively coarse CFD grid; Insufficient infos about the running conditions;

10. Animation of deformation