AutoMesh - Recent Threads

RE: Mastering Turbine Mark-II Meshing – A Step-by-Step Automation Guide Using Fidelity Python API

Gaurav — Wed, 21 May 2025 09:03:00 GMT

Thanks KBBKBB

Mastering Turbine Mark-II Meshing – A Step-by-Step Automation Guide Using Fidelity Python API

Gaurav — Mon, 19 May 2025 02:06:28 GMT

In this case study, we will be examining the meshing workflow process for a turbine nozzle guide vane, specifically the Mark II model. The primary objective is to demonstrate the capabilities of the Fidelity Python API script in accurately generating a mesh for a 2D high-pressure turbine blade. Through this example, we intend to illustrate how the API can efficiently manage complex meshing tasks, providing users with valuable insights into various key meshing parameters.

https://support.cadence.com/apex/ArticleAttachmentPortal?id=a1OPP000000sTWU2A2&pageName=ArticleContent

RE: Mastering Turbine Mark-II Meshing – A Step-by-Step Automation Guide Using Fidelity Python API

KBBKBB — Wed, 21 May 2025 07:42:25 GMT

Hi Gaurav,

I just wanted to thank you for the great contributions you’ve made. Your detailed Python scripts and explanations are extremely helpful for understanding and automating workflows in Fidelity.

I really appreciate the time and effort you put into sharing your knowledge. Keep up the good work!

Best regards

RE: Export .geomTurbo to .IGS

Hans Hager — Fri, 20 Dec 2024 09:24:42 GMT

That helped; Thank you :)

Export .geomTurbo to .IGS

Hans Hager — Thu, 19 Dec 2024 11:20:11 GMT

Dear Numeca-Community,

I lost my original CAD for a comrpessor blade. Right now I have only the .geomTurbo File for grid generation.
Is it possibly to export back into a neutral CAD format like *.iges

Best regards,

Hans

RE: Export .geomTurbo to .IGS

Gaurav — Fri, 20 Dec 2024 09:18:09 GMT

Use IGG for importing the .geom turbo and export.

RE: 3D mesh generation failed. Could not create fillet geometry. Cannot create valid fillet lofted surfaces.

Hans Hager — Fri, 04 Oct 2024 08:57:14 GMT

Yes, it is related.

Can the solution be, that the second B2B plane has to have an offset from the first B2B plane at the hub, higher than the fillet radius?

Regards

Hans

3D mesh generation failed. Could not create fillet geometry. Cannot create valid fillet lofted surfaces.

Hans Hager — Mon, 24 Apr 2023 07:26:44 GMT

Hi,

I am using AutoGrid5 and I tried to mesh a turbine Blade (structured mesh, highly staggered, O4H) with Butterfly fillet topology (Method: B2B section offset).

Unfortunately I get the following error message:

What could be the reason?

Regards,
Hans

Option to group surfaces not available in the Geometry context

Colinda — Mon, 05 Aug 2024 13:41:26 GMT

I have a .step file and made a mesh on it.
Then I realized that several surfaces needed a refinement. So I wanted to group these.

I go back in the Geometry context and select the surfaces (all under the same boundary) and right-click.
To my surprise the option to group them does not appear.

When I open the same step file in a new project from scratch and try to group these same surfaces, it works. So I guess there must have been something in the process of setting up the domain and mesh that caused the grouping to no longer be available. But I can’t figure out why.

RE: Option to group surfaces not available in the Geometry context

Colinda — Mon, 05 Aug 2024 13:43:33 GMT

The group option does not appear when the mesh is already generated.

Go to the Mesh context and right-click on the Mesh setup of the previously created mesh. Select to delete the mesh. It is not necessary to delete the mesh setup, so the settings will remain available.

An alternative is to use Local selections in the Mesh context. This does not require to delete the previously generated mesh.

Structured Vs. Unstructured Mesh

CFDTech — Tue, 26 Sep 2023 07:06:09 GMT

Appropriate mesh generation is essential for an accurate solution, faster convergence, and reduction of numerical diffusion. Poorly formed meshes introduce numerical error, increasing the computational cost of convergence. For especially poor elements, the numerical order may be locally reduced to promote convergence and stability or, even worse, the solution may fail to converge entirely.

Structured	Unstructured
1. Structured grids are identified by regular connectivity (ordered type by indices such as i, j, and k and the topology is easily associated to the next indices). The possible element choices are quadrilateral in 2D and hexahedra in 3D. The regularity of the connectivity lets you conserve space because neighborhood relationships are defined by the storage arrangement.	1. Unstructured grids have no such ordering. Therefore, a node is associated to a single integer index and the topology is known by associating connections of the node with the neighboring nodes. Compared to structured meshes, the storage requirements for an unstructured mesh can be substantially larger because the neighborhood connectivity must be explicitly stored.
2. Grids can be Cartesian or Curvilinear (usually body-fitted). In the Cartesian grid, grid lines are always parallel to the coordinate axes. In the Curvilinear grid, coordinate surfaces are curved to fit boundaries. There is an alternative division into orthogonal and non-orthogonal grids. In orthogonal grids (for example, Cartesian or polar meshes), all grid lines cross at 90º. Some flows can be treated as axisymmetric, and in these cases, the flow equations can be expressed in terms of polar coordinates (r, θ), rather than Cartesian coordinates (x, y), with slight modifications.	2. Grids can be triangular (tetrahedral), quadrilateral (hexahedral), polygon (polyhedral), and hybrid. Unstructured grids can accommodate completely arbitrary geometries. Grid generators for such meshes are also very complex.
3. Advantages of structured girds are better convergence, a high degree of quality and control, less memory and time resolution (does not need the storage of any connectivity table because the mesh is defined according to a specified pattern).	3. Advantages of unstructured grids are the ability to handle complex geometries and the possibility to generate anisotropic meshes in the far field without cell clustering and propagation, ideal for marine applications, for example, to capture the free surface and keep the lower cell count.
4. Structured meshes can be generated using a variety of well-defined mathematical techniques, ranging from algebraic to conformal mapping to the solution of partial differential equations.	4. Algorithms used to generate unstructured meshes are generally based on the Delaunay algorithm or an advancing front technique.

Unstructured meshes are generated using Fidelity Hexpress and Fidelity Pointwise.

Two different generation approaches are available in Fidelity Hexpress and can serve different purposes based on the inputs and needs of the user:

Volume-to-surface approach: Generation of the mesh starts from the domain volume, and it is successively adapted to the geometry. This approach is particularly convenient for complex geometries and unclean geometry inputs (for example, non-watertight geometries, non-conformal triangulations).

Surface-to-volume approach: Generation of the mesh starts from surfaces of the geometry and is successively propagated to the domain volume. This approach can produce very high-quality unstructured meshes with very tidy cell patterns on the surfaces. It requires conformal geometries.

Fidelity Autogrid technology automates the laborious geometry preparation process without losing any detail of the geometry and delivers quality meshes ready for CFD simulations in real real-time and is used for turbo machinery configuration.

Figure 1: Unstructured mesh generation done by Fidelity Hexpress

Figure 2: Structured mesh generation done by Fidelity Autogrid

Fidelity Pointwise can generate structured multi-block, unstructured, hybrid, and overset meshes for viscous simulations with precise control over point placement and clustering to get the desired resolution. At the same time, Pointwise’s core meshing methods produce cells of high quality to ensure convergence and accuracy in your CFD solution.

Figure 3: Unstructured mesh generation done by Fidelity Pointwise

Team CFDTech

Cadence Design Systems

RE: 3D mesh generation failed. Could not create fillet geometry. Cannot create valid fillet lofted surfaces.

Gaurav — Thu, 03 Aug 2023 08:04:31 GMT

This post is related to "3D mesh generation failed. Could not create fillet geometry. No blend surfaces created". Please verify

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

ms1007 — Fri, 05 May 2023 08:35:06 GMT

Hi,

The fillet size you are using is big, and channel that you are using from the CAD geometry is not large enough.
You need to carefully consider the size. Does the fillet fits in the channel or if it is touching the next blade in the passage, or the Rotor Stator interface. According to this, you need to adjust the fillet size or size of channel, to be able to get a fillet, with correct geometry.

Manthan

3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

Hans Hager — Wed, 03 May 2023 15:12:58 GMT

Hi,

so I want to mesh one passage of a turbine stator with hub and shroud fillet. I used a mesh that I work with and uploaded the Aachen Stator2 into it by "Import and Link CAD" (importing .geomTurbo and then using link to Blade/link to trailing edge/link to leading edge).

When I try to mesh it, the following error occurse.

What might be wrong?

Regards,

Hans

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

Hans Hager — Fri, 05 May 2023 07:13:58 GMT

Thank you Manthan for the effort you are putting in. I forgot to post the size.

I scaled the Aachen 2nd Stator to fit a Hub of 9.66 inch and shroud of 11,35 inch.

From leading to trailing edge axial chord it is about 1,35 inches.

The fillets are 0,1 inch.

For my specific case the constant radius approach will not work.

Regards,

Hans

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

ms1007 — Thu, 04 May 2023 14:52:21 GMT

Thanks for providing more details.

The issue seems due to the geometry creation of the fillet and not in the mesh generation. i cannot comment on the size of the channel and where the fillet border is located, but it seems like a large fillet. In that case I think it would be more convenient to go with different geometry approach rather than B2B section offset. For instance, constant radius approach may work in this case.

I generated the mesh on stator 2 of Aachen Turbine, and it worked successfully with B2B section offset approach as well. But, indeed dimensions of your case may differ and hence the geometry of fillet.

I hope it helps and answers your query.

Manthan

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

Hans Hager — Thu, 04 May 2023 10:26:30 GMT

Hi Manthan,

thank you for your reply.

I don't have a CAD file of the fillets. I create the fillets in AutoGrid.

I also tried to change the .geomTurbo to native. It didn't work.

Further information on my fillet creation (everything is in inches):

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

ms1007 — Thu, 04 May 2023 10:10:28 GMT

Hi Hans,

I will need more information, on how you are trying to define the fillet geometry at hub and shroud.
Importing the .geomTurbo file will create a blade geometry, after that you need to define the fillet by selecting the surfaces from CAD file and linking it to the hub. (If you are trying to link a user defined Hub fillet with a .geomTurbo file). After linking fillet to the hub, you need to adapt and control settings of hub fillet by going into properties menu in Hub fillet and set the parameters to generate flow paths.

I recommend you to go through the tutorial 11 in the advanced section in Autogrid5 manual. In the last section of tutorial, a user defined fillet is created from CAD geometry, in the same way you are trying to get a mesh with a fillet.

Please let me know if you have any further questions.

Manthan

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

ms1007 — Wed, 03 May 2023 08:59:52 GMT

Hi Hans,

Please allow me to explain better to be able to help you.
I am not sure what is the computation case you are dealing with. But, it is generally unusual to have 12 blades in the same row. You have the error "Could not create fillet for blade 12". If you meant to simulate a full stator of turbine, instead of using the multiple blades in a single row you should use only single blade in a row and use the option " number of mesh passage" to 12. It will automatically duplicate with 12 blades in a 360 degree view.

Usually Multiple blades in a single row option is used when you have splitters within the blade row or if you have an aircraft engine configurations, where it is interesting to mesh the stator upstream the nozzle arms with staggered angle varying with the azimuthal location of the blade.

If you have exact same blades as in the case of normal stator of turbine, you should use single blade in a passage with a periodicity equal to the number of blades, and you will be able to generate the mesh with blade fillets on each blade.

I hope I am clear now, let me know if you have further queries.

Regards,
Manthan

3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

Hans Hager — Mon, 24 Apr 2023 08:20:15 GMT

Hi,

I am trying to mesh a full annulus in AutoGrid5 by taking the mesh of one passage and then duplicating it to get a full meshed turbine stator annulus. Now the Fillet mesh works for one passage (O4H topology with Butterfly fillet geometry; Method:from meridional; structured mesh; highly staggered; matching periodicity).

Unfortunately I get the following error message:

Somewhere along the way on the annulus, the fillets cannot be generated anymore.

What could the reason be?

Regards,

Hans

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

Hans Hager — Wed, 03 May 2023 08:08:59 GMT

Hi Manthan,

sorry, it wasn't clear. I am using multiple Blades within ine row.

Regards,

Hans

RE: 3D mesh generation failed. Could not create fillet geometry. No blend surfaces created.

ms1007 — Tue, 25 Apr 2023 15:24:44 GMT

Hi Hans,

I am not sure know how you are proceeding with the case. I think you do not need to use the duplicate option for the multiple blades. But instead use the option of "number of mesh passages" in the row properties and regenerate the 3D mesh. You should be able to get a mesh with blade fillets on each blade. Duplicate option is used when you have multiple blades within the same row. You can have a look at documentation (user Guide/ Blade Editing/ Duplicate Blade Geometry)

Regards,
Manthan

RE: Export to .msh fluent format

Teja971201 — Tue, 07 Mar 2023 13:15:51 GMT

Thank you so much for your help Domen and Colinda. I will request them.

Export to .msh fluent format

Teja971201 — Tue, 28 Feb 2023 14:06:55 GMT

Hello,

I recently acquired a student license for Omnis and am working on only rotor simulations. I have generated the mesh and when I export it, I cannot see the fluent .msh file format. Could someone help me with that? I used that option in the old version of Autogrid with IGG. But is there an option like that in the new OMNIS5.2?

Thanks.

RE: Export to .msh fluent format

Colinda — Tue, 07 Mar 2023 12:49:10 GMT

I confirm that for the moment the free student license still gives access to AutoGrid5, the predecessor of Omnis AutoGrid.

The installation files can be requested at academic-cfd@cadence.com with a justification of need, on an exceptional basis.