[bobdorm14]

Hi everyone,

I am doing aeroelasticity simulation for 2D airfoil.I'm trying to do a simulation of a wing that is both pluging*and pitching.


I have created 2 types of mesh using GAMBIT sotware

1)structured mesh (consist of square grid)

2)unstructured mesh consist of triangles shape grid.

I run the simulation in fluent by compiling the UDF .c file for both type of mesh.

everything goes well for unstructured mesh.when I click "preview mesh motion" button under dynamic mesh I can see the movement of the airfoil.but the quality for this type of mesh is very low.

for structured mesh,fluent gives me an error "Update-Dynamic-Mesh failed". Negative cell volume detected" for the same model.I enable the 3 methods (layering,smoothing and remeshing) under "mesh method"

can anybody help me on this.

How to eliminate error "Update-Dynamic-Mesh failed. Negative cell volume detected" in Fluent? - ResearchGate. Available from: https://www.researchgate.net/post/Ho...cted_in_Fluent [accessed Jun 15, 2016].

[`e`]

The dynamic mesh model in Fluent can handle both structured and unstructured meshes. However, MDM does not remesh structured cells -- only unstructured cells.

What degree of motion is your aerofoil experiencing? You may be able to employ the smoothing mesh method (no modifications of the mesh; only moves nodes based on either a diffusion equation or spring system).

There are three zones to specify as dynamic mesh zones: (1) aerofoil (probably a user-defined type which both translates and rotates the aerofoil boundary); (2) sides of domain (set as deforming); and (3) interior (also set as deforming).

The negative cell volume error is shown when the mesh has been updated in a way to cause a negative cell volume (non-physical). Possible factors for causing this error include: (1) overlapping nodes; and (2) significant mesh motion (relative to cell size) per step. These factors are related and you could try to reduce the time step to avoid major mesh displacements (see also: implicit mesh update).

[kywong5]

Hi bobdorm14, are you able to solve the problem as mentioned?
I'm facing the same situation too.

[Sandeep Reddy]

Originally Posted by kywong5

Hi bobdorm14, are you able to solve the problem as mentioned?
I'm facing the same situation too.

Me too, did you get any solution?

[lfla]

Encountering the same problem have you got a solution for this? As the only one i have had was to put a very coarse mesh which i would rather not. Thank you

[Ved1994]

I assume most of us get this error because the moving boundary is travelling more than half of the adjacent cell height in one time step. So, if you are limited by hardware, a solution would be to coarsen the mesh. If you have good firepower at your disposal, you can further decrease the time step to a point so that at any time step during the simulation time your object is not travelling more than the adjacent cell height in one time step.

[iancmlositano]

Originally Posted by bobdorm14

Hi everyone,

I am doing aeroelasticity simulation for 2D airfoil.I'm trying to do a simulation of a wing that is both pluging*and pitching.


I have created 2 types of mesh using GAMBIT sotware

1)structured mesh (consist of square grid)

2)unstructured mesh consist of triangles shape grid.

I run the simulation in fluent by compiling the UDF .c file for both type of mesh.

everything goes well for unstructured mesh.when I click "preview mesh motion" button under dynamic mesh I can see the movement of the airfoil.but the quality for this type of mesh is very low.

for structured mesh,fluent gives me an error "Update-Dynamic-Mesh failed". Negative cell volume detected" for the same model.I enable the 3 methods (layering,smoothing and remeshing) under "mesh method"

can anybody help me on this.

How to eliminate error "Update-Dynamic-Mesh failed. Negative cell volume detected" in Fluent? - ResearchGate. Available from: https://www.researchgate.net/post/Ho...cted_in_Fluent [accessed Jun 15, 2016].

Negative cells mean such cells do not follow the right hand rule (RHR). Can you check the orientation of those blocks of cells? It may be that during meshing, these cells have been oriented to go against the flow. The solution would be to just re-orient them.

[BasilVarghese]

Can anyone please help me in finding time step value for flapping motion of fan(piezoelectric fan) whose length is 64mm,width of fan is 12mm.I need a velocity of 2-2.5 m/s. When I give some values to time step, it gives only rotary motion while previewing motion of fan. Piezo fan is having vertical configuration in my simulation.
How can I find time step value?

[vinerm]

The description is not very clear. Could you share more details and, possibly, an image. Please do not use third party site for image. Use Attachment option available within the post.