Autodesk Simulation CFD - Calculator Volume Flow Rate Need Help. Tks

[Anonymous]

Dear Mr Jon Wilde,

I had designed a part, like picture below. And I want to reduce the Volume Flow Rate from 10-20l/h to 1-2l/h by a narrow way for water. But in Simulation I still got outface water have a same Volume Flow Rate with inface water. Can you help me to explain why and how to fix it? 

Here is my CFD file: it 13Mb, I can't upload to this forums...http://www.mediafire.com/download/mk7tu100ttgds97/TEST+PART+CFD.cfz

AND the narrow way for water

I have attached my DWG file design and my CFD Simulation. If possible, pls help me to understand why the Volume Flow Rate isn't change . Many thanks and Best Regards.

Hoang Su

[Anonymous]

Dear Mr Jon,

Thank you for your help. But can you advice where is the "Results Plane" and the "desired location", I can't find the Bulk Calculator.

Here is my taskbar.

Thanks and Best Regards.

Hoang Su

[Jon.Wilde]

You will find all of this under 'planes'

Start with running through this tutorial 🙂

Thanks,

Jon

[Anonymous]

Dear Mr. Jon,

Thanks so much.

But when I click Bulk, there is nothing to choice ( I mean I want to choice outlet section). And I see the display like below

I choice all then I click calculate. My question is:

1. Did I do calculate right way?

2. The Result above is outlet right?

3. I wouldn't see the flow ( sample is litre/hour) in the display result above. Can you help me to have it?

Thanks and Best Regards,

Hoang Su

[Jon.Wilde]

Hi Hoang,

Would you be able to take a few moments to run through the tutorial I suggested above? This takes you through some of the basics and should leave you in a position to use the bulk calculator.

Kind regards,

Jon

[Anonymous]

Dear Mr. Jon,

Yes, I saw, but too many informations and I dont know which information I need. I saw their compare 2 Scenario but I just have 1 Scenario and I don't want to compare, I just want to display the outlet volume flow in Bulk.

Maybe I haven't know your intent. Sorry for that.

Thanks and Best Regards.

Hoang Su

[apolo_vanderberg]

Hoang,

  As Jon mentioned, please step through the tutorials (or the Self-Paced Fundamenatls) on the Help system.

You are not positioning your Plane at the outlet to measure the pressure or flowrate, these are all basc items that are listed in the Help

Here is a video that also discusses this

[Anonymous]

Dear Mr Apolo and Mr Jon,

I have follow 2 video you advice. And I make a planes on outlet section like below

Then I click on that plane, and right click on it. I choice Bulk...( I dont know highlight region mean with my design, because when I change, 1 and none, nothing become yellow like video, I choice the default, None like this)

I choice Volume Flow ( l/h mean Liter /hour)

My Question is:

1. Did I do right way?

2. Why the Flowrate too many like this : 808 liter/hours ( it impossible)

Thanks and Best Regards.

Hoang Su

[apolo_vanderberg]

Hoang,

 You have succsessfully used Bulk to measure the flowrate through your model.

Now, whether or not this value is 'impossible' or not will depend on a variety of items:

The geometry / restriction of the domain

Did we apply the correct pressure drop to the domain for your expectations? (i.e. is 800l/h impossible because you're expecting 10l/h but at a different pressure drop?)

Is your mesh sufficient to capture the appropriate gradients and physics?

Did you run this out to convergence?

This comes back to being similar to the duscsion you started at the beginning of this thread:

You assigned a flowrate and stated that you expect a different value at the outlet. We showed that due to conservation of mass we will always have the same flowrate at inlet and outlet assuming we are not seeing a change in material properties.

Using a pressure drop on a model will generate the flowrate taht corresponds to that assignment and the geometry at hand. If this doesn't match you're expectations, more information as to where teh expecation comes from would be needed as you might not be matching the CFD assumptions to those in the real world.

[Anonymous]

Now I have the yellow circle at plane. But I dont know why the volume flow too much: 806 liter/hour....

Did I go wrong some where?

Thanks and Best Regards

Hoang Su

[Jon.Wilde]

Now we are getting to some specifics 🙂

Is the model converged?

Did you use ADV5 and just have a pressure driven analysis?

What flow rate are you expecting to see?

What are the flow speeds - are they compressible?

Thanks,

Jon

[Anonymous]

Dear Mr Apolo,

Thanks for your reply.

1. "Is your mesh sufficient to capture the appropriate gradients and physics?" I dont know how many mesh is enough but I mesh with default like below

2. "Did you run this out to convergence?" I dont understand your question but I have solve it with CONTINUE FROM 0 and ITERATIONS TO RUN 500 and ofcourse Im using ADV 5

3. My pipe inlet just 2mm diameter inside and 4mm diameter outside. With input 1bar. I just think it very small, can't get 808l/h

Thanks and Best Regards.

Hoang Su 

[Anonymous]

Here is my design, And I expect it just under 10 liter/hour. Can u download it and test?

Thanks and Best Regards

[Jon.Wilde]

Hi,

Please share a support file (CFZ) from CFD so we can check your setup faster 🙂

Thanks!

Jon

[Anonymous]

Dear Mr Jon

FYI

Many Thanks.

Hoang Su

[Anonymous]

Sorry, it CFD file, here is CFZ file, thanks

[Jon.Wilde]

Thank you.

Actually, going by your previous image showing the outlet area as 688 mm2, this does not give a 2mm diameter 🙂

Might help explain the difference

A few pointers also:

1. Suppress the solid parts from the mesh
2. If you are enabling gap refinement, I would use 3 gap elements (meshing -> advanced)
3. You might like to think about a mesh refinement region where your geometry goes from a very small gap into the larger outlet

Kind regards,

Jon

[apolo_vanderberg]

Correct,  the inlet and outlet are 20mm and 30mm respectively

Hoang, check your dimensions. As far as I can see the results do no seem out of the realm of possibility.

[Anonymous]

Dear Mr Jon and Mr Apolo,

Thank you both. Let me try with right mesh. But I also have another question:

1. I design my part in autodesk inventor, and I export it to dwg, then I open it from Inventor Fusion, then simulation it from autodesk sumulation cfd, is it right?

2. I will check with mesh, but I dont know why "mesh refinement region where your geometry goes from a very small gap into the larger outlet". Is that mean with very small gap, the simulation can not calculate, it need to larger for simulation right?

3. If larger outlet is necessary, and with the same inlet condition ( Pressure inlet = 1bar), can I use ratio for volume flow rate?. That mean if my original outlet area is A, and my original volume flow is B. And the larger outlet area is C, and the result volume flow outlet in Bulk is D.

Can I use B = (A*D)/C   ?? to deduced my original volume flow?

Thanks and Best Regards.

Hoang Su 

[apolo_vanderberg · Accepted solution]

Hoang,

 1. That is a lot of un-needed eporting and importing.   You can take the model from Inventor straight to CFD, or you can open the Inventor file in Fusion and launch to CFD. No need to export a dwg to import in to Fusion. Most likely you lost the units somehow and the part may have been scaled up causing larger opening than you expect. Correct this and launch in direct from Inventor. - This is covered in the Help - using th launcher that is built in to Inventor for CFD

2. Meshing is critical to capture physics. We have a whole section talking about the importance of mesh and how to refine the mesh. With the mesh you sent, you are too coarse to properly capture physics and you will want to refine the mesh to improve the resutls.

3. This is difficult to answer, due to #1 above if your geometry is not the right size it might mean taht more dimensinos than just the inlet/outlet are incorrect meaning that you might be running a part that is physically incorrect overall.

Please go back and re-check the model size

[Anonymous]

Dear Mr Apolo,

I did it, and when I choice simulation direct from inventor, the size going right, not bigger anymore. Maybe that is the reason my model become scale up.

Let me check with my design and go back with you later. 

Thanks. 😄

btw, i'm watching your video : https://www.youtube.com/watch?v=NIY0hwUqpko

Excellent bro.

Thanks and Best Regards.

Hoang Su