August 29, 2023 at 6:07 pm

fares abbara

Subscriber

For better understanding of my model, here is a summarized problem statement.

Model Specifications are as follows:

- Linear elastic tube with young’s modulus 0.108 MPa and 0.49 Poisson ratio.
- Tube thickness 1mm and inner diameter 8.5mm.
- Non-Newtonian fluid model.
- Outlet boundary condition: 1300 Pa.
- Inlet boundary condition: time dependent sinusoidal velocity (amplitude 0.1 m/s, frequency 2Hz).

The model ** runs without errors with time step of 0.01s**. Model becomes

**in the tube when the simulation runs**

__highly unstable with unreasonable deformations__**. (other time steps lower than 0.01 also cause failure).**

__at 0.001s time step size__

I have tried to:

- Check the contact between the solid and fluid domain for any gaps that could be causing instability.
- Experiment with constant and time dependent linear inlet velocity profile.
- Running the simulation in steps (run fluent first and then export data as initial conditions for coupled analysis).
- Experimented with numerical stabilization controls in the structural domain.