Learning Forum

[AndreaGaggi16]

Hello everybody,

My simulation is working (transient thermal cooling of a cylindric volume) and I have created different materials I want to compare. I have the same geometry and mesh in every case. I want to see how the results change, when I apply the different materials to my geometry (a simple cylindric volume consisting only of 1 material - which I want to vary). I would like to visualize the different results in 1 chart.

In the attached picture you can see the 2 ideas A and B I have how to structure the workbench.

A: Everything is done in 1 complete Fluent package

B: I create a tree structure where the geometry and mesh is the source for 10 different calculations and results cells.

 

 

How can I most easily achieve my goal to compare the materials?

 

Thank you,

Andrea

[Ananth Narayan]

Firstly create a geometry system, then import or draw cylinder

Next, create fluid flow fluent (cfd or cfx), link geometry to it

Later mesh it with name selection and apply B.C's with material and solve it

Finally duplicate fluid flow fluent into extra 2 copies then change only material of it and solve each.

 

[AndreaGaggi16]

What does B.C's mean?
Is the structure you are talking about like that?

[Ananth Narayan]

B'C's mean Boundary condition. Not exactly like you shown. Please have a look below: (currently I don't have ansys student need to install)

 

Hope you understand.

[AndreaGaggi16]

Hi Ananth!

Thank you very much. I don't understand exactly what would go wrong if I do it like in the picture I sent last. Can you tell me the difference between your solution and mine? 

Thank you,

Andrea

[Rob]

It should work like the original idea. To get the curves I'd build & run the Fluent model and save the line from an xy plot out of the software. Read all the various lines into Excel (or back into Fluent - via the xy plot panel: that's how I produced graphs for my PhD 20 years ago) and then plot all curves on one graph. 

 

Ananth's suggestion does much the same but via the Workbench tools. Good idea. 

[AndreaGaggi16]

I don't want to use the same fluent flow for all the materials and only save the graphs because if I want to have the graph for another time step I have to do the calculation again (and the calculation for each material needs 5-10 minutes at the moment. I tried adaptive time step settings but it needed the same time).

Is it possible to save the calculation results for each material in an extra file and reload them whenever I want? Then I could have only 1 Fluent flow and save the calculation results one for each material and reload it when I want to have the graph for another time step.

Second question: I still don't understand why this solution I proposed would not work and why Ananth's solution is different. I have duplicated after solving and viewing the result as he said and ANSYS has created the blue connection lines automatically. But I duplicated the cell "solution", because I assumed if I want to try another geometry I would have to change it only once and the other fluent flows would update automatically as the cells geometry and mesh are connected. Ananth duplicated the whole fluent flow I guess so there is no connection between the 2 fluent flows? Is this the difference? And why should my solution not work? Still confused.

 

[Ananth Narayan]

You can save data's files like pressure, temperature etc., under fluent. You should not link geometry and mesh to duplicated one. Take a look at image.

1. Make a geometry like cylinder you said

2. Link to fluent or you can use geometry in fluent. Mesh them with named selection as inlet, outlet etc.,

3. On fluent make proper conditions, like type of viscous flow, material etc., save the plots before running solution. Refer https://youtu.be/l8cqntjoaaI

4. Now duplicate the fluid flow fluent into 2 copies.

5. On each of the duplicated fluent's change the material in setup tab.

6. Solve each of them. But make sure you give proper file name for plots else, may be overwrite the previous one.

7. Use excel or other application to plot graph

.

[AndreaGaggi16]

Thank you very much for the detailed advice, Ananth! 
I will try this. 
I have three questions left:

1. Why should I not link geometry and mesh to duplicated fluent flow? What is the problem?

2. A question about step 3. of your description: Which plots should I save? I am not interested in the mass flow rate. The information I would like to save is the temperature at each point in the cylinder at each time of the simulation. Is that possible?

3. What if I want to try another cylinder geometry? Then I have to change the geometry in each fluent flow, right? I have 10 material types, not 3 in reality. I only drew 3 to show the case in general. So I would have to change the cylinder geometry 10 times in each fluent flow right?

Thank you!
Andrea

[Ananth Narayan]

1. Your actually solving the fluent system and duplicating makes every data duplicate. So it is unnecessary to link again. If you want to link then after solving create another fluent then link geometry, mesh and again you need to define properties say for fluid material, velocity, inlet temperature etc. But when you duplicate you need to change only material type, leaving others as it is.

2.Yes you can save lot of parameters like temp, velocity, viscous etc., There are lot of option for you to save.

3. Yes you change geometry, when you do you will see refresh symbol which needs to be updated. Update your simulation. Make sure you have a copy of ANSYS file before you change geometry. This is optional.

[Rob]

If you use Option B then one geometry update should mean you can just use the project update to rerun everything. If you set all the surfaces in Fluent for post-processing then it'll be reasonably quick to get all the images etc too as they'll also be copied if you duplicate the original Fluent (only) workflow rather than creating a new one & connecting to mesh. 

The order you do/copy/connect workflows will be important so I'd advise experimenting, especially if you have a small model.