open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello!

I'm running LES (telemac-3D with Smagorinsky turbulence model) for my work. To estimate the sub-grid TKE, I'll need to estimate sub-grid length scales, which requires knowing local cell sizes.

Estimating cell sizes will be easy if the mesh is uniform; however, I have areas refined in my mesh, which makes the grids not uniformly large. I was wondering if there's a quick way in Telemac or Blue Kenue that I could obtain cell sizes of the whole mesh?

Any input will be much appreciated!

Thanks a lot,
Jason

Not sure about how accurate you're looking for...

If you start with a T3 2D mesh (instead of a 3D mesh); you could extract an "edge length" mesh, which would give the average distance to all of a node's neighbours for all nodes. So you'd then have an edge length mesh. From there, you could extract the region of interest (or extract beforehand) and then use the submesh to get a sense of the average based on the stats for the whole submesh.

Then, you could estimate the average cell height and do the appropriate multiplication by hand to get an estimate.

You can also extract the volume of the 2D mesh using the "Analyse" button in the T3 Mesh Toolbar.

Again, not sure if that's what you want... but Blue Kenue offers those things for you right now.

In the future, maybe extracting a distribution object containing the distribution of all cell volumes could be interesting to add to Blue Kenue if this would be generally useful for people.

Good luck!

Kindly... Alan

Thank you, Alan! It works!

Hi Jason,

Edit->T3 Mesh->Analyse Mesh...
Provides some element size statistics.

Hope this helps... Martin

This is helpful. Thanks, Martin!

FYI - The next Blue Kenue installer will allow you to extract the cell volumes distribution from a 3D Tetra Scalar Mesh.



While I'm at it... anything else you'd like to request closely related to this request?

Kindly... Alan

Please upgrade to BK 3.12.22 - beta to get this new functionality.

Kindly... Alan

Thanks, Alan. This is great! Is it possible to get individual cell volumes (maybe as a mesh) from a 3D Tetra Scalar Mesh? Or it has to be done by the method you shared earlier- have an edge length mesh and then multiply it with vertical grid size?

Thanks,
Jason

Hi Jason,

Not sure I understand exactly where you're trying to go!

The latest BK now allows you to extract the distribution of all cell volumes for the current frame from a 3D mesh.

Why do you need the individual cell volumes? Not sure I know how to give you want you want... Do you want a new 3D scalar mesh with the cell volume as the scalar value? Or a simple table of element ID and volume values?

Originally, I thought you were trying to get an estimate of the overall cell volume for a mesh (i.e. a quick way in Telemac or Blue Kenue that I could obtain cell sizes of the whole mesh) and I've given you a distribution so that you can look at mean cell volume, min cell volume, max cell volume, etc.

However, perhaps I didn't understand what you were asking for properly... a little more explanation and/or example might help me get to where you're trying to go...

Kindly... Alan

Hello Jason,

When you write you are "running LES (telemac-3D with Smagorinsky turbulence model)", what do you exactly write in your steering file?
HORIZONTAL TURBULENCE MODEL = 4 and/or VERTICAL TURBULENCE MODEL = 4?
In that case, I would not say you run LES, see the implementation in $HOMETEL/sources/telemac3d and subroutines VISSMA, SMAGO and SMAGO3D subroutines.

Anyway, to get voume around a node, you can implement in USER_PRERES_TELEMAC3D the saving of variable VOLUPAR in one of the 4 private arrays available for users.
See an example of such an implementation in
$HOMETEL/examples/telemac3dcone/user_fortran/user_preres_telemac3d.f e.g.

Hope this helps,

Chi-Tuan