Tanker Flow Simulation

kurt1080 · April 16, 2011, 18:28

I am new to the forum and new to the world of CFD. I am currently working on my University senior project which involves analyzing the current aerodynamic state of milk hauling semi tankers. I have modeled all tanker/tractor models in CATIA V5 and am now attempting to get some baseline aerodynamic data however I am struggling with STAR-CCM+. I can import my file (total assembly of tractor/trailer via .igs file) and using the remesher tool I can get a decent mesh. I have gone through a couple of the tutorials and i think that i know how to set up the basic parameters however i am at a loss as to how to create a wind tunnel region around my part! How do I model that in STAR-CCM+? Any and all help would be much appreciated! Also, how difficult is it to set up a drag coefficient report within the simulation? The Cd as well as some basic turbulence visualization is what I am after.

kurt1080 · April 17, 2011, 16:46

I am trying to do as simple of wind tunnel simulation as I can, essentially it is for a comparative analysis; i.e. baseline aerodynamic drag vs. aerodynamic drag with side skirts, tapering, etc. At 55MPH. Would it be possible/better to use STAR-CD over STAR-CCM+?

alastormoody11 · April 19, 2011, 06:29

Hi,

The drag and lift coeffcient calcuation are easy just go to reports and say new report, choose force coefficient, choose the correct direction vector for obtaining either lift or drag.

Regarding the turbulence parameters they are accessible by creating a scalar scene.

I do not undersatand why you did not create the surrounding geometry in CATIA itself however you can also do that in STARCCM+.

Considering the fact that you want to extract drag from your simulation I would advise you to have prism layers in the mesh and chk the validity of the turbulence model you are using by verifying that the wall y plus is within the recommended range. If you have time you also might want to consider a sensitivity study.

kurt1080 · April 23, 2011, 19:28

Thanks for your help. I ended up getting some tutorial software which really helped me. However I am having some issues with the drag coefficient numbers I am getting. I am running the simulation at 55mph and I have entered in all the appropriate parameters such as frontal area, however the numbers I am getting are significantly lower than what they should be. Any helpful tips/reminders about setting this up to get accurate results? The direction is set at [0,1.0,0]

alastormoody11 · April 25, 2011, 01:21

Hi,

Please firstly please check the reference values you are using to calculate the Cd, ensure that they are correct.

Secondly what wall treatment are you using if you are using something which requires specific wall y plus plz chk whether that is in the specified range.

Also is your meshing upto the mark?

April 16, 2011, 18:28	Tanker Flow Simulation	#1
kurt1080 New Member Kurt DeVries Join Date: Apr 2011 Posts: 3 Rep Power: 15	I am new to the forum and new to the world of CFD. I am currently working on my University senior project which involves analyzing the current aerodynamic state of milk hauling semi tankers. I have modeled all tanker/tractor models in CATIA V5 and am now attempting to get some baseline aerodynamic data however I am struggling with STAR-CCM+. I can import my file (total assembly of tractor/trailer via .igs file) and using the remesher tool I can get a decent mesh. I have gone through a couple of the tutorials and i think that i know how to set up the basic parameters however i am at a loss as to how to create a wind tunnel region around my part! How do I model that in STAR-CCM+? Any and all help would be much appreciated! Also, how difficult is it to set up a drag coefficient report within the simulation? The Cd as well as some basic turbulence visualization is what I am after.

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April 17, 2011, 16:46		#2
kurt1080 New Member Kurt DeVries Join Date: Apr 2011 Posts: 3 Rep Power: 15	I am trying to do as simple of wind tunnel simulation as I can, essentially it is for a comparative analysis; i.e. baseline aerodynamic drag vs. aerodynamic drag with side skirts, tapering, etc. At 55MPH. Would it be possible/better to use STAR-CD over STAR-CCM+?

April 19, 2011, 06:29		#3
alastormoody11 Senior Member Join Date: Jun 2009 Posts: 100 Rep Power: 16	Hi, The drag and lift coeffcient calcuation are easy just go to reports and say new report, choose force coefficient, choose the correct direction vector for obtaining either lift or drag. Regarding the turbulence parameters they are accessible by creating a scalar scene. I do not undersatand why you did not create the surrounding geometry in CATIA itself however you can also do that in STARCCM+. Considering the fact that you want to extract drag from your simulation I would advise you to have prism layers in the mesh and chk the validity of the turbulence model you are using by verifying that the wall y plus is within the recommended range. If you have time you also might want to consider a sensitivity study.

April 23, 2011, 19:28		#4
kurt1080 New Member Kurt DeVries Join Date: Apr 2011 Posts: 3 Rep Power: 15	Thanks for your help. I ended up getting some tutorial software which really helped me. However I am having some issues with the drag coefficient numbers I am getting. I am running the simulation at 55mph and I have entered in all the appropriate parameters such as frontal area, however the numbers I am getting are significantly lower than what they should be. Any helpful tips/reminders about setting this up to get accurate results? The direction is set at [0,1.0,0]

April 25, 2011, 01:21		#5
alastormoody11 Senior Member Join Date: Jun 2009 Posts: 100 Rep Power: 16	Hi, Please firstly please check the reference values you are using to calculate the Cd, ensure that they are correct. Secondly what wall treatment are you using if you are using something which requires specific wall y plus plz chk whether that is in the specified range. Also is your meshing upto the mark?