CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > General Forums > Main CFD Forum

Need help with arriving at the results of a journal paper

Register Blogs Members List Search Today's Posts Mark Forums Read

Like Tree4Likes
  • 1 Post By aerosayan
  • 1 Post By aero_head
  • 1 Post By vivjk94
  • 1 Post By aerosayan

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   January 31, 2021, 13:26
Default Need help with arriving at the results of a journal paper
  #1
Member
 
Vivek MJ
Join Date: Oct 2020
Location: India
Posts: 53
Rep Power: 5
vivjk94 is on a distinguished road
Hello All,
i have a 3d gear pump journal paper and i need to reproduce the result shown in the paper.
For the problem, i have used Ansys cfx and modeled a similar geometry and similar gear pump setup(including boundary conditions. However, i am not able to match the results shown in the journal paper.
The max and min Pressure value at gear meshing interface doesnt match with the paper and so does my velocity values.

So i kindly ask, Please guide me and let me know where i am i going wrong. I wish to learn from my mistakes and understand what needs to be done.

Here is the link to all the files
https://drive.google.com/drive/folde...za?usp=sharing

Kindly help me out
Thanking you,
Vivek
vivjk94 is offline   Reply With Quote

Old   January 31, 2021, 13:27
Default
  #2
Member
 
Vivek MJ
Join Date: Oct 2020
Location: India
Posts: 53
Rep Power: 5
vivjk94 is on a distinguished road
Also, i have used immersed body solver and selected the 2 gears as immersed solids. The inlet is set to Total pressure (stable) at 1 psi. The outlet is set to opening in order to avoid critical overflow error. The outlet pressure is 100 psi and set to opening pres. and dirn ,The two gears are rotating at 10,000 rpm and both the gears are rotating in opposite directions.
My main issue is that the two gears when meshing produce negative and max pressure cavity at the inter teeth cavity. I am not able to get that in my simulation which is strange.

Last edited by vivjk94; January 31, 2021 at 20:05.
vivjk94 is offline   Reply With Quote

Old   January 31, 2021, 23:15
Default
  #3
Senior Member
 
Sayan Bhattacharjee
Join Date: Mar 2020
Posts: 495
Rep Power: 8
aerosayan is on a distinguished road
I don't use ANSYS, so take my advice with a grain of salt.

From your vector plot, I have a hunch that you're probably using a coarse mesh.
Could you try to increase the mesh density, and try running the simulation again?
aero_head likes this.
aerosayan is offline   Reply With Quote

Old   January 31, 2021, 23:50
Default
  #4
Senior Member
 
Kira
Join Date: Nov 2020
Location: Canada
Posts: 435
Rep Power: 8
aero_head is on a distinguished road
I agree with aerosayan, and I do use ANSYS

Your mesh is likely too coarse; does the paper mention anything about the number of nodes or grid-cells the other used or any other mesh parameters?

What kind of simulation is it (LES,DES,RANS)? You need to be careful with mesh size, especially with the first two of my suggestions.

Also, it helps to append your images right to the post, as most people do not like following links.
aerosayan likes this.
aero_head is offline   Reply With Quote

Old   February 1, 2021, 01:26
Default
  #5
Member
 
Vivek MJ
Join Date: Oct 2020
Location: India
Posts: 53
Rep Power: 5
vivjk94 is on a distinguished road
Quote:
Originally Posted by aerosayan View Post
I don't use ANSYS, so take my advice with a grain of salt.

From your vector plot, I have a hunch that you're probably using a coarse mesh.
Could you try to increase the mesh density, and try running the simulation again?
Yes, thank you for the feedback. I found that improving mesh ,gave me higher velocity results but i am not able to get the negative pressure contour.
aerosayan likes this.
vivjk94 is offline   Reply With Quote

Old   February 1, 2021, 02:55
Default
  #6
Senior Member
 
Sayan Bhattacharjee
Join Date: Mar 2020
Posts: 495
Rep Power: 8
aerosayan is on a distinguished road
Quote:
Originally Posted by vivjk94 View Post
Yes, thank you for the feedback. I found that improving mesh ,gave me higher velocity results but i am not able to get the negative pressure contour.

As aero_head pointed out, you need to be careful about the mesh sizing for different numerical schemes. Be careful with that.


You might also try reducing the timestep value since this is a transient simulation.

Since you're able to return back with the result within a few hours of me answering the question, I don't think that your mesh size and timestep value are small enough to accurately capture the solution.

Try generating a dense mesh, and use a small timestep, such that your simulation takes at least 4-6 hours.

Make sure that you're writing the solution result after every (say) 1000 iterations (or 10 minutes of simulation), and make sure you're also writing the "solver restart file" every (say) 1000 iterations (or 10 minutes of simulation), such that you can see your results and you can restart your solver if something goes wrong.
aero_head likes this.
aerosayan is offline   Reply With Quote

Old   February 1, 2021, 08:33
Smile Thanks for your suggestion
  #7
Member
 
Vivek MJ
Join Date: Oct 2020
Location: India
Posts: 53
Rep Power: 5
vivjk94 is on a distinguished road
Quote:
Originally Posted by aerosayan View Post
As aero_head pointed out, you need to be careful about the mesh sizing for different numerical schemes. Be careful with that.


You might also try reducing the timestep value since this is a transient simulation.

Since you're able to return back with the result within a few hours of me answering the question, I don't think that your mesh size and timestep value are small enough to accurately capture the solution.

Try generating a dense mesh, and use a small timestep, such that your simulation takes at least 4-6 hours.

Make sure that you're writing the solution result after every (say) 1000 iterations (or 10 minutes of simulation), and make sure you're also writing the "solver restart file" every (say) 1000 iterations (or 10 minutes of simulation), such that you can see your results and you can restart your solver if something goes wrong.
Thanks to both of you, i will run the simulation at a smaller time step and a finer mesh. All this while i had thought that my geometry was the issue and tried recreating the gear cad model. I will update when i get the right result. Your suggestions helped me a ton.
vivjk94 is offline   Reply With Quote

Reply

Tags
ansyscfx, cfd analysis, gearump, help for a newbie

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
replicating the CFD results Astik Kulkarni Fluent Multiphase 1 November 12, 2019 04:51
Error Interpolating Results onto New Mesh nammeh CFX 1 March 26, 2019 12:08
Save Results automatically by APDL Command ansyxyz ANSYS 1 June 5, 2018 08:16
comparison of stream function contours with a paper mariam.sara FLUENT 1 July 24, 2017 04:44
Creating a tool to interpolate results Luis Batista OpenFOAM Running, Solving & CFD 2 April 11, 2013 08:15


All times are GMT -4. The time now is 04:24.