[mila.d.b]

Hello people!

I'm kind of new on CFD, and I'll do a 3 phase CFD simulation (gas-liq-solid) in an UASB bioreactor (do not considering reaction). I have tried some strategies for meshing (on ICEM with hexa mesh) and I had problems with quality... Now I'm trying to use Ansys meshing or ICEM with tri/tetra mesh....

The point is that there are just to many options of meshing strategies, and I'm lost... If you could help me I would be really grateful!

First of all: Ansys meshing or ICEM? Wich one should give me the best results for a good meshing? (considering that I will start with a coarser mesh and refine after a few times, to get a mesh independent result at Fluent).

Secondly: with strategy should best fit my geometry that is attached?

Thank you So much!

Camila

[amin.z]

Originally Posted by mila.d.b

Hello people!

I'm kind of new on CFD, and I'll do a 3 phase CFD simulation (gas-liq-solid) in an UASB bioreactor (do not considering reaction). I have tried some strategies for meshing (on ICEM with hexa mesh) and I had problems with quality... Now I'm trying to use Ansys meshing or ICEM with tri/tetra mesh....

The point is that there are just to many options of meshing strategies, and I'm lost... If you could help me I would be really grateful!

First of all: Ansys meshing or ICEM? Wich one should give me the best results for a good meshing? (considering that I will start with a coarser mesh and refine after a few times, to get a mesh independent result at Fluent).

Secondly: with strategy should best fit my geometry that is attached?

Thank you So much!

Camila

Hi,

Generally ICEM can generate higher quality mesh in comparison to Ansys meshing, but it's easier to learn ansys meshing and it's usually faster to generate grid using ansys meshing.

Your geometry is fairly complex, I think it'll be too hard to generate a full structured grid for it, I think generating some tet mesh for top and bottom and hex mesh for middle of the tank will be good at first step

[mila.d.b]

Thanks so much Amin! I really do appreciate your help! I've been struggling with this mesh for a few months (that's for my master's, and I'm by myself)...

Actually I have already kind of learned to use ICEM, at least for basic mesh. I was thinking about doing a Robust Octree in the beggining, and than doing a quick delaunay after... So I would have a tetra mesh.

Is it possible to do the mesh for just some parts at ICEM as it is on Ansys mesh? In all my attempts I did the mesh for the whole geometry at ICEM (I did a few tutorials at Ansys mesh as well)...

Thanks again!

[Antanas]

Originally Posted by mila.d.b

Thanks so much Amin! I really do appreciate your help! I've been struggling with this mesh for a few months (that's for my master's, and I'm by myself)...

Actually I have already kind of learned to use ICEM, at least for basic mesh. I was thinking about doing a Robust Octree in the beggining, and than doing a quick delaunay after... So I would have a tetra mesh.

Is it possible to do the mesh for just some parts at ICEM as it is on Ansys mesh? In all my attempts I did the mesh for the whole geometry at ICEM (I did a few tutorials at Ansys mesh as well)...

Thanks again!

Don't load unwanted geometry to ICEM.

[amin.z]

Originally Posted by mila.d.b

Thanks so much Amin! I really do appreciate your help! I've been struggling with this mesh for a few months (that's for my master's, and I'm by myself)...

Actually I have already kind of learned to use ICEM, at least for basic mesh. I was thinking about doing a Robust Octree in the beggining, and than doing a quick delaunay after... So I would have a tetra mesh.

Is it possible to do the mesh for just some parts at ICEM as it is on Ansys mesh? In all my attempts I did the mesh for the whole geometry at ICEM (I did a few tutorials at Ansys mesh as well)...

Thanks again!

Sorry, it's not clear for me what you want to do, Can you explain more?
and unfortunately I have no skill in ICEM, I'm using ANSYS Meshing

[mila.d.b]

Originally Posted by amin.z

Sorry, it's not clear for me what you want to do, Can you explain more?
and unfortunately I have no skill in ICEM, I'm using ANSYS Meshing

Yes, sure I can. I'm doing my masters, and it consists in studying the fluidynamics of this reactor. It is a bioreactor (Upflow Anaerobic Sludge Bed), where we have a sludge bed inside (at the bottom) and an inlet of effluent. And the biogas is generated in that reactor. The idea is to simulate a three-phase model of this reactor, considering the solid (sludge), liquid (effluent) and Gas (biogas) and to validate it in order to scale up the reactor...

The only problem is that I'm a beginner, so it is not that easy for me to do it...

[-Maxim-]

Since you are a beginner, I would recommend unstructered ANSYS meshing - this will be tricky enough. Don't forget a mesh sensitivity study...
You flow will be quite complex (3 phases) - you will be busy enough with that problem so that you don't want to spend (waste) a month or longer to properly learn how to mesh that complex upper part in ICEM. (At least I assume you won't have a year for your Master's thesis).

As mentioned above, you could mesh the simple middle part (cylinder) with an Ogrid as hexa mesh in ICEM and the rest with unstructered tet mesh in Ansys meshing.

[mila.d.b]

Originally Posted by -Maxim-

Since you are a beginner, I would recommend unstructered ANSYS meshing - this will be tricky enough. Don't forget a mesh sensitivity study...
You flow will be quite complex (3 phases) - you will be busy enough with that problem so that you don't want to spend (waste) a month or longer to properly learn how to mesh that complex upper part in ICEM. (At least I assume you won't have a year for your Master's thesis).

As mentioned above, you could mesh the simple middle part (cylinder) with an Ogrid as hexa mesh in ICEM and the rest with unstructered tet mesh in Ansys meshing.

Thanks fo the tips. I did a mesh with ICEM, using Robust Octree for beggining. Than I did again a Quick Delaunay mesh for the volums.

The quality seems good (above 0,2 the quality parameter) , and I oppened that on Fluent, and it didn't say that there is a problem. How could I make sure that the mesh is good?

thanks again