CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > Software User Forums > ANSYS > FLUENT

How to extract Lift and Drag coefficients from Ansys Fluent

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

Like Tree4Likes
  • 2 Post By RaiderDoctor
  • 1 Post By AlexanderZ
  • 1 Post By AlexanderZ

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   June 12, 2018, 08:28
Post How to extract Lift and Drag coefficients from Ansys Fluent
  #1
New Member
 
Abdul Rehman
Join Date: Jun 2018
Posts: 1
Rep Power: 0
Abdul_Rehman is on a distinguished road
I'm doing a project on the analysis of this underwater glider. I have to extract lift and drag values at different wing spans. I set the boundary conditions and run the calculations but when results are displayed, I can't understand which value is the lift or drag coefficient. I'm new to CFD so, I lack basic information.
I want to know how can I extract lift and drag coefficients from it and also how can I set angle of attack?
P.S I'm using k-epsilon model, with an inlet water velocity of 0.3 m/s. I have attached some pictures.
Attached Images
File Type: png 0.45 pic1.PNG (9.6 KB, 153 views)
File Type: png 0.45 pic2.PNG (7.7 KB, 103 views)
File Type: png 0.45 pic3.PNG (5.4 KB, 83 views)
File Type: jpg Geometry.jpg (87.5 KB, 128 views)
File Type: jpg Contours.jpg (107.2 KB, 140 views)
Abdul_Rehman is offline   Reply With Quote

Old   June 12, 2018, 10:49
Default
  #2
Senior Member
 
Join Date: Dec 2016
Posts: 152
Rep Power: 10
RaiderDoctor is on a distinguished road
Hey, welcome to the world of CFD. Luckily, you're problem seems like an easy one. Solving for the lift and drag coefficients need to be set prior to calculation. I'm not quite sure of a way to do it afterward...


First, check out this video as it basically answers your question.

https://www.youtube.com/watch?v=WrqwX1GQfeg
It wouldn't be a bad idea to watch parts 1-6, just to get a better understanding of the program.


So, what you need to do is set up a solution monitor for both coefficients that will calculate the values in real-time. This is a very important part of every simulation, as it can let help you in judging convergence (more on that in a second).


In case you are running a new version of Ansys than what was described in the video, the steps involved in setting up a solution monitor are as follows: Double-click Report Definitions. A new menu should pop up, click New, and highlight Force Report. In the drop-down menu that appears, there should be one for both Lift and Drag. Click Drag first (the method for setting up Lift is the exact same). This will bring up a new menu, called Drag Report Definition. Name it "cd-1" or whatever you like, and select the object that you'd like to calculate drag over underneath the Wall Zones section. Underneath the Create section, select Report File, Report Plot, and Print to Console. These are important, as a file will enable you to plot the values for later graphs, a plot will show you the calculated value in real time, and you'll be able to see the exact value in the console. Click OK to close the menu.



In the Report Definitions menu, click Report File Definitions. This will bring up a new menu. Here, we want to specify the frequency that Fluent will record the calculated values. Select the rfile of the report definition you just created (i.e. if you named the definition cd-1, select cd-1-rfile). Click Edit. This will bring up a new menu. Down towards the bottom, specify the frequency you'd like the data to be recorded. I personally like to see the calculated value every iteration. This helps me judge convergence better. If you are doing a steady-state simulation, this will be the default answer. Click OK to close the menu, and Close to close the Report File Definitions menu. Now, click Report Plot Definitions, which will bring up a new menu. Select rplot of the definition you just created (i.e. if you named the definition cd-1, select cd-1-rplot). Click Edit, which will bring up a new menu. Again, I like to get data every iteration, so that I can judge convergence. Change plot title if you like, although I never do. Click OK to exit this menu, and Close to exit the Report Plot Definitions menu.



Repeat the process for the other coefficient. And that's about it. As you calculate, you will see real time solutions of both coefficients in Fluent. As the solution progresses, both quantities should eventually converge to a final answer. This is important, because it helps you monitor how your solution is actually doing. For instance, if your simulation converges via continuity, but has not reached a final value for the lift coefficient, your solution is not really converged. So keep calculating.


Happy simulating, and good luck!
RaiderDoctor is offline   Reply With Quote

Old   January 1, 2021, 17:42
Default extracting data
  #3
New Member
 
Pramodh K
Join Date: Jul 2020
Posts: 2
Rep Power: 0
pramodhkumaresh is on a distinguished road
Hi, this explanation is quite helpful. But I would also like to know how I can extract data from this plot.

For instance, if I perform a transient simulation is there a possibility to extract data points of lift and drag with respect to the time/ number of iterations as a txt or excel file.
pramodhkumaresh is offline   Reply With Quote

Old   January 4, 2021, 01:20
Default
  #4
Senior Member
 
Alexander
Join Date: Apr 2013
Posts: 2,363
Rep Power: 34
AlexanderZ will become famous soon enoughAlexanderZ will become famous soon enough
you can write them into file, this setting is available when you are making these monitors
pramodhkumaresh likes this.
__________________
best regards


******************************
press LIKE if this message was helpful
AlexanderZ is offline   Reply With Quote

Old   January 4, 2021, 03:14
Default
  #5
New Member
 
Pramodh K
Join Date: Jul 2020
Posts: 2
Rep Power: 0
pramodhkumaresh is on a distinguished road
Thank you for your reply.

Yes, I have created a report file. Could you please tell me how I can read this file for the required data? becos I think a .out file is created
pramodhkumaresh is offline   Reply With Quote

Old   January 4, 2021, 03:31
Default
  #6
Senior Member
 
Alexander
Join Date: Apr 2013
Posts: 2,363
Rep Power: 34
AlexanderZ will become famous soon enoughAlexanderZ will become famous soon enough
just read it with any text editor, excel is also possible
you can put any other format instead of .out
pramodhkumaresh likes this.
__________________
best regards


******************************
press LIKE if this message was helpful
AlexanderZ is offline   Reply With Quote

Old   February 22, 2021, 23:26
Smile
  #7
New Member
 
Eliyaz Saraj
Join Date: Feb 2021
Posts: 3
Rep Power: 5
eliyaz123321 is on a distinguished road
Hi, I am also doing a project for my final year university using ANSYS Fluent/ CFD to analyse aerodynamically Drag and Lift on a vehicle.
i have already done my mesh and solution fully converged.
i am trying to find out if there is anyway to plot the drag around the different parts of the vehicle.
by this i mean the different values of drag coefficient from the front to the rear of the car.
i have shown an image as an example of what i mean.

thanks in advanced
eliyaz123321 is offline   Reply With Quote

Old   February 22, 2021, 23:29
Default
  #8
New Member
 
Eliyaz Saraj
Join Date: Feb 2021
Posts: 3
Rep Power: 5
eliyaz123321 is on a distinguished road
forgot to post example of image.
its basically the development of Cd over the vehicles length.
how would i go about doing this on my own car?

eliyaz123321 is offline   Reply With Quote

Old   February 22, 2021, 23:30
Default
  #9
New Member
 
Eliyaz Saraj
Join Date: Feb 2021
Posts: 3
Rep Power: 5
eliyaz123321 is on a distinguished road
https://postimg.cc/r0jNj2zJ
eliyaz123321 is offline   Reply With Quote

Old   March 22, 2021, 08:37
Default
  #10
Senior Member
 
Join Date: Dec 2016
Posts: 152
Rep Power: 10
RaiderDoctor is on a distinguished road
Hm, what about if you take an isoclip of some width over the length of the car, and then extract the average measurements from it?
RaiderDoctor is offline   Reply With Quote

Reply

Tags
ansys 15.0, cfd, drag and lift, fluent, glider

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
Calculation of lift and drag coefficients on airfoil CoolHersheys OpenFOAM Post-Processing 5 September 27, 2021 06:04
Lift and Drag Force - 3D Wing ANSYS FLUENT jonsyesause FLUENT 0 April 26, 2017 12:31
Lift and Drag pattern change wit FLUENT 16 and 13 PISO for same mesh n solver setting arunraj FLUENT 0 June 2, 2016 22:58
Can fluent get the lift and drag coefficients of the two walls (in different directio yuyuxuan FLUENT 8 January 10, 2014 20:13
Lift and Drag Coefficients Reliability Luis FLUENT 2 December 27, 2005 14:45


All times are GMT -4. The time now is 03:58.