Learning Forum

[LoïcS]

Greetings,

I'm doing a transient simulation of a plate moving normal to a fixed surface. The initial air gap (between the plate and the fixed surface) is set at 0.2 mm. Dynamic mesh (smoothing and remeshing mesh) is defined in fluent. The moving plate mesh is tetrahedral elements with a dimension of 10µm. The model is laminar and compressible air. The sinusoidal movement of the plate is defined with an udf. The number of time steps is set at 215 and the time step size at 2.5e-5.

The simulation complete well for displacement amplitude up to 0.8 mm but diverges for displacement amplitude of 0.1 mm. When using the simple method, the simulation stop after 40 time steps (19%). I have try to run with implicit update, it stops at 169 time steps (79%). When trying the PISO method, it stops at 15 time steps (7%).
Please, how can I fix this floating point exception?


More details on the model

                               

 

 

5 pressure outlet, 1 fixed wall, 1 moving plate

[Federico Alzamora Previtali]

Hello, 

I see that you have only 3 cells across the width of your box, is this correct? I would imagine that refining the mesh would help. The Dynamic Mesh setup appears to be Ok, but I would suggest in the Remeshing Settings to do the following:

• Click on Mesh Scale Info and use this information to define the Min/Max/Skewness parameters for remeshing. This will better preserve the distribution of your mesh.
• Change the Remeshing interval to 1

[LoïcS]

Thanks for your helpful insights.