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

Ship Self Propulsion Results in Negative Torque value

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

Reply
 
LinkBack Thread Tools Search this Thread Display Modes
Old   April 20, 2023, 08:44
Default Ship Self Propulsion Results in Negative Torque value
  #1
New Member
 
Çağan
Join Date: Apr 2022
Posts: 3
Rep Power: 4
caganini is on a distinguished road
Hi everyone, i have been working on ship self propulsion simulations including 2 dof (heave and pitch) with Virtual Disk method, using StarCCM+



There is no problem with setting the simulation up and running it, almost for all cases i get proper thrust value but negative torque value.



I use Hull Performance Workflow to set up the simulations, use thrust option for virtual disk, and enter the open water table (including kq instead of 10kq).



At first trials i have encountered "thrust input cannot be negative" error, and realized that it stems from Total Resistance estimation going negative at some point, which leads to negative thrust value and then the simulation stops. To overcome this i have employed absolute value of Total Resistance and since then simulations work just fine (not being sure if this is a proper way of overcoming this problem).



I want to know if it is natural to get negative torque values, and if not, what can be the most possible reasons and from which point should i start investigating the problem.



Thanks in advance.
caganini is offline   Reply With Quote

Old   April 23, 2023, 06:16
Default
  #2
Senior Member
 
Lefteris
Join Date: Oct 2011
Location: UK
Posts: 337
Rep Power: 15
Aeronautics El. K. is on a distinguished road
Can you share the definitions of the coordinate systems that you use (with pictures) and the definition of the resistance report?
Also the inputs in the virtual disk model in the physics.
__________________
Lefteris

Aeronautics El. K. is offline   Reply With Quote

Reply

Tags
negative torque., starccm+, virtual disk model

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
Too much trim on the ship and "zero or negative volume" error alderemert STAR-CCM+ 3 February 7, 2022 21:24
How to resolve negative torque values for a VAWT in Ansys Fluent? khadija8 FLUENT 1 April 13, 2020 07:59
[blockMesh] BlockMesh FOAM warning gaottino OpenFOAM Meshing & Mesh Conversion 7 July 19, 2010 14:11
High pressure in rhopSonicFoam results in negative pressure shangzung OpenFOAM 0 November 5, 2009 03:24
positive and negative torque forces Wei-Haur Lam CFX 0 March 19, 2008 07:45


All times are GMT -4. The time now is 18:21.