Learning Forum

[mleary29]

 Hello,

I am currently trying to figure out which platform to begin CFD on with the intention of running simulations concerning how a point-absorber device responds in a steady-state flow system with ocean currents, and before I begin I just want to learn if there are any limitations to the student version of this software. Are you able to have many computational nodes? Essentially, what are the limitations compared with a normal license?

Thank you for the help,

Matt

 

[peteroznewman]

Matt, the ANSYS Student license is limited to 512K cells/nodes for a CFD model. A full license has no such limitation.

[Fco.Herbert]

Hi peteroznewman,

Many thanks for answering mleary29's question. I wonder if ANSYS Student is limited by the number of CPU cores that can be used in parallel CFD simulations?. E.g., can I run Ansys Fluent with 200 cores considering a mesh that has less than 512K cells/nodes?

Best regards,

[pgl]

The ANSYS Student product is limited to 16 cores.  

[uconcorde]

Hi peteroznewman,

I am wondering if the word "nodes" in "the 512k cells/nodes" means the number of nodes of the mesh.

Also, in parallel mode, no matter how many cores I used, the total cells of the case is limited to 512k?

Thanks.

uc

[peteroznewman]

In a CFD model, if you add the number of cells to the number of nodes in the mesh, the sum should be less than 512k.  I have seen some models where that did not seem to be strictly enforced.

In a Structural model you add the number of elements to the number of nodes in the mesh, the sum should be less than 32k.  That is more strictly enforced and sometimes, the solver goes off and creates a lot of contact elements and refuses to run because the additional elements created push the model over the 32k limit even though the mesh you see in Mechanical was < 32k.

Doesn't matter how many cores you use but it has to be less than or equal to 16.

[Sarabel]

hello,

in my geometry they are less than 50 bodies and less than 300 surfaces. I can't delete any bodies or change anything in the model. What can be the problem?thanks.

[peteroznewman]

If you meshed beyond the limit, then returned below the limit, there is a defect that latches the out-of-bounds condition that does not get properly reset. The workaround is to Update Geometry from Source to reset the limit. Read this and see if it helps.

[srikrishnan]

Hallo,

One more question regarding the maximum limit for nodes/cells.

1) I am using ansys mesher for my geometry and I don't intend to solve in fluent or cfx. Does the limit for nodes or cells change now ?

If yes, could you please mention it ?

Because I have reached upto 6.5million nodes ( 16million elements )

 

2) Any difference in limitation for quad and tet mesh ?

[TimFethke]

"In a Structural model you add the number of elements to the number of nodes in the mesh, the sum should be less than 32k.  That is more strictly enforced and sometimes, the solver goes off and creates a lot of contact elements and refuses to run because the additional elements created push the model over the 32k limit even though the mesh you see in Mechanical was < 32k."

Hi,

The website states nodes/elements which I thought meant that neither nodes, nor elements should exceed 32k.(https://www.ansys.com/academic/free-student-products). Maybe it would be nice to change that to clarify. (something like nodes+elements).

Anyway, do you maybe have a suggestion for a workaround for people who do have to solve problems that go beyond the limits of the student license without buying Ansys? I know this is a long shot but I thought it is worth to ask. I am working on my graduation project and I want to do a modal analysis of two parts that are connected. I can analyze them separately but it is necessary that I examine the dynamic behavior of the combined system. 

Thanks for your input

[peteroznewman]

Hi Tim,

I see in your other post you are trying to use Substructuring so that might work.

In general, you can idealize the model and be very efficient with the use of nodes in the mesh. For example, replace thin solid sections with sheet bodies to use shell elements instead of solid elements.  Replace long thin sections of the model with beam elements instead of solid elements. Slice the geometry to use half the number of solid elements by meshing with hex elements instead of tet elements. Use symmetry if applicable.

If you want to upload a Workbench Project Archive of your model, I can make specific suggestions.

Regards,

Peter

 

[srikrishnan]

Hi

I asked these questions earlier.

 

1) I am using ansys mesher for my geometry and I don't intend to solve in fluent or cfx. Does the limit for nodes or cells change now ?

 

If yes, could you please mention it ?

 

Because I have reached upto 6.5million nodes ( 16million elements )

 

 

2) Any difference in limitation for quad and tet mesh ?

[peteroznewman]

Haven't you already answered your own question by going past the Student license limits?

I believe the limits are only in the solver, not the mesher.

No difference in quad and tet mesh limits.

[srikrishnan]

Hi,

Just wanted to be sure.

Thanks anyways.

 

regards,

krishna

[mertozgen]

Hi Peter, I'm trying to do a structural analysis of a slightly complex part with Ansys Workbench Student version. How can I decrease the node/element number so I won't exceed the limitations of student version?

[Rob]

You just need to apply coarser mesh settings and/or reduce the complexity of the model. The purpose of Student and Teaching software is to learn how to use it: for complex models you may need Research (for academic purposes) or commercial (if you're doing this for money). 

[mertozgen]

how can I apply coarser mesh? Thanks.

[tsiriaks]

Under Mechanical GUI, when you select 'Mesh' under the project tree on the left menu, you should see "Details of 'Mesh'" box show up. Under there you can define a coarser mesh size ('Element Size' , etc)

Thanks,

Win

[Fabricio1]

Dear

I would like to know if among the limitations of ansys for students is the impossibility of performing a joint calculation of ansys cfx with the transient ansys structural

[peteroznewman]

You can't do 2-way FSI with the Student license.

You can do 1-way FSI with the Student license. Solve the flow and apply the pressure to a Structural model.

[Fabricio1]

So chapter 23 of ansyscfxtutorials oscillation plate with two-way fluid structure interaction cannot be resolved with student license. Right?

[Fabricio1]

How can i solve this oscillation plate issue with 1-way FSI?

 

[amarti]

Hello,

I am trying to perform a 2D study of an atmospheric boundary layer. I am aware of the limitations I'll have once I have to mesh the domain but I am experiencing problems way before.

I would need to create a 1000 m high, 6000 m long rectangular domain. But after creating my sketch, Design Modeller doesn't allow me to create a surface (that will be my domain) from this sketch.

Is there any domain size limitation apart from the element number in the Student licence? Or may I be doing something wrong?

(Just to be clear, the rectangle is fully closed and if I reduce the dimensions the error disappears).

Thank you.

[Rob]

You need large body support, or just scale the domain to 1m high by 6m long and scale back in Fluent.  

[amarti]

By "large body support" you mean some feature not included in this license?

I'll try scaling in the meantime.

Thank you for your answer.

[Rob]

No, it should be in the settings somewhere: it moves the decimal place so adjust the domain size limits. It has no effect on the cell count cap. 

[M F]

 

Hi, 

I am a mechanical engineering student in my last year of university. I have to create a magneto-static simulation for a structure I have made on SolidWorks. I am using Ansys Workbench with a student license to run this software. The issue I am facing is that the solver runs up to only 10% and produces this error message: 

The option of EX on the MP command is either not available for this version of ANSYS or the appropriate product was not selected for this session. Contact your ANSYS support person for more information.

NUMBER OF WARNING MESSAGES ENCOUNTERED= 0

NUMBER OF ERROR MESSAGES ENCOUNTERED= 1

Can someone please help me figure out where I have gone wrong?

 

[SURJIT SINGH]

Hi,

Is it possible to make 3d model inside the Ansys student version

[David AUGER]