I have determinated my problem. I post a figure in that i show the problem. How can i eliminate this surface. For this motive i don't create the mesh.

You seem to have overlapping surfaces, in that case I think you need to fix the CAD first, as Hexpress won't be helpful for this matter.

I resolved the problem. Now I do the mesh of two volumes, but for the third volume when I try to do the optimization phase the process failed.I try to modificy the optimization level but the optimization don't finish.

Check in the log file what is happening. It should point an issue with a specific edge or face.

There are concave cells and negative cells. How can i reduce them?

check where exactly this is happening and create local refinements maybe.

I imported the mesh in Numeca,but when i set the boundary condition of inlet there is a problem:

Erros:Can't read "ith_bc(phys_var;min_value;StaticPressureExtrapola ted,24,1,6)":no such variable"

hi "jackr84".......first of all check the boundary conditions-in HEXPRESS refinement is done on only on those surfaces which are tagged as WALL. Check the things out like geometry is clean & valid....if not try to clean in 3matic(no need of it, as you are saying that u were having x_t file; in hexpress itself u can clean), define proper taget cell size-TCS (TCS=initial_size/2^(refinement_level)), & hexpress has an built in algorithm which has success rate of 99.98% removing concave cells through default optimization step.

Hexpress
 

Hi,

I'm new with hexpress. Are there any tutorials?

Thanks in advance

Hexpress view 41
 

Hello Everyone,
Am facing some difficulty with the configuration file (.conf)in
HEXPRESS VIEW41. Is there any one who is using the same software.
Being a beginner i couldn't get the solution for my problem :(:confused:.
Please do reply.

Regards,
DJ SANTOSH KIRAN.

Dear DJ Santosh Kiran,

Maybe you can describe your problem such that people with experience in HEXPRESS/View can help you?

Best regards,
Colinda.

Dear friends,

I am trying to carry out a grid independence study with 3 different mesh size using HEXPRESS. I want to set the grid refinement ratio(r) to 1.4.

My question is; should we apply this value(r) only for Initial Mesh step at the beginning and keep the other parameters same? However, when i applied this refinement ratio for only in Initial Mesh step, the difference between medium and fine grid counts is very small, i.e medium count is 2M and fine is 2.7M. Is it also necessary to change the refinement values ​​on the surfaces and curves? How can i ensure that the grid refinement ratio will strongly enforced in the x, y, z direction as we move from the coarse to the medium, or from medium to fine? Can you help me if you have any knowledge or experience about this issue?

Any help will be greatly appreciated.

Grid independence study
 

Hey Lazarus

As you might have read in the paper from Tokyo Workshop 2015 NUMECA recommends to perform grid dependence studies based on changing the initial cell sizes. This allows to refine the whole fluid volume and not only the areas right next to the solid. Hexpress defines the initial mesh as an integer number of divisions in each direction. That is why the refinement ratio 1.25 is ideal, because it allows to keep integer number of cells (6, 8, 10 for example).

In practice:
- Medium mesh: the initial mesh needs to have a number of cells in each direction that is multiple of 4. For example, 20 cells in X direction, 8 cells in Y direction, 8 cells in Z direction. Try to keep the initial mesh as isotropic as possible, the default proposed by Hexpress is isotropic.
- N coarse = 3/4*N medium, N fine = 5/4*N medium, where N is the initial number of cells in X, Y and Z directions. If you need more meshes just continue with the same ratio.
- The diffusion (Adapt to geometry > Global > Advanced > Refinement diffusion) needs to be 1 for coarse, 2 for medium and 3 for fine. This diffusion is a measure of how far from the solid surface the refinement propagates in number of initial cells. The reason to change the diffusion is to ensure the distance covered by refinement is the same in all meshes.
- All surface refinements need to be defined with a defined "Max nb of refinements" and "target cell size" = (0,0,0) --> this way the different initial meshes will lead to different mesh sizes.

Thanks

Dear guys;

I have some problems in using hexpress/hybrid for generating mesh inside a geometry with interior zero-thickness walls. could you please help me in this regard?

Bests,