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

Negative Drag Values for only some surfaces?? Please help

Register Blogs Community New Posts Updated Threads Search

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   May 2, 2020, 07:39
Default Negative Drag Values for only some surfaces?? Please help
  #1
New Member
 
Join Date: Apr 2020
Posts: 8
Rep Power: 6
Jordan1997 is on a distinguished road
Hi there, my deadline for my senior project is fast approaching and any help would be extremely appreciated right now!

Using Star-CCM I'm modelling an external aerodynamics simulation of a fixed wing UAV (see attached photos). I have run preliminary simulations using the realizable k-epsilon turb model with a target Y+ of 30, all converged nicely.

I have separate surface controls for each of my surfaces, and upon running a drag report for each surface I'm getting some as positive and some as negative?? In this case my fan, hinge point and wing/fuselage joint are fine, but the fuselage, H-Tail, V-Tail and Wing all are producing negative results? I think the report is set up correctly.

To add to it, upon looking at the y+ in a scalar field I notice there are some missing sections of the geometry in the scene which have not appeared anywhere else. (See Photo)

Any ideas please, again any help would be much appreciated.
Attached Images
File Type: png 1.png (100.0 KB, 7 views)
File Type: png 2.png (42.1 KB, 5 views)
File Type: jpg 3.jpg (45.0 KB, 5 views)
File Type: png 4.png (131.1 KB, 6 views)
File Type: png 5.png (5.8 KB, 7 views)
Jordan1997 is offline   Reply With Quote

Reply

Tags
negative drag values, star-ccm


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 07:04
Airfoil with simpleFoam and kOmegaSST: high drag values? Tsiolkovsky OpenFOAM Running, Solving & CFD 6 November 21, 2018 06:56
Negative Drag in Natural Convection Ashwini FLUENT 0 July 13, 2018 06:26
Negative Drag on Airfoil jasonbot FLUENT 0 October 1, 2013 07:23
[blockMesh] non-orthogonal faces and incorrect orientation? nennbs OpenFOAM Meshing & Mesh Conversion 7 April 17, 2013 06:42


All times are GMT -4. The time now is 11:18.