Shear forces on floating bodies using X39

KevinMcTaggart · October 3, 2024, 09:48

I'm making progress with forces on a ship in steady flow. I discovered the input variable X39 when reviewing the code in file 6DOF_obj_forces_stl.cpp. X39 determines the shear force computation method. The code is quite easy to understand. Will this variable be documented in future versions of the manual? Could anyone provide advice regarding X39? I'm getting reasonable results for X39=2, which uses a wall function. Due to the relative coarseness of the mesh, X39=0 underpredicts shear forces and X39=1 overpredicts shear forces, with both methods evaluating shear forces based on the local velocity gradient. I've also implemented my own wall function, and I look forward to sharing results when available.

valgrinda · October 19, 2024, 10:22

Hi Kevin,

we are currently working on this ourselves. We have successfully validated the new 6DOF algorithm for floating bodies in waves and now we are focusing on ship hydrodynamics. It would be great if we could have a chat with you about this option and your own implementation. Maybe you could drop me an email?

KevinMcTaggart · October 22, 2024, 13:59

Hello Hans.

I emailed you and look forward to discussing further. My impression is that the computation of the flow field is working well, and that accurate evaluation of shear forces will require moderate effort.

Kevin

October 3, 2024, 09:48	Shear forces on floating bodies using X39	#1
KevinMcTaggart New Member Kevin McTaggart Join Date: May 2018 Posts: 15 Rep Power: 8	I'm making progress with forces on a ship in steady flow. I discovered the input variable X39 when reviewing the code in file 6DOF_obj_forces_stl.cpp. X39 determines the shear force computation method. The code is quite easy to understand. Will this variable be documented in future versions of the manual? Could anyone provide advice regarding X39? I'm getting reasonable results for X39=2, which uses a wall function. Due to the relative coarseness of the mesh, X39=0 underpredicts shear forces and X39=1 overpredicts shear forces, with both methods evaluating shear forces based on the local velocity gradient. I've also implemented my own wall function, and I look forward to sharing results when available.

October 19, 2024, 10:22		#2
valgrinda Super Moderator Hans Bihs Join Date: Jun 2009 Location: Trondheim, Norway Posts: 403 Rep Power: 19	Hi Kevin, we are currently working on this ourselves. We have successfully validated the new 6DOF algorithm for floating bodies in waves and now we are focusing on ship hydrodynamics. It would be great if we could have a chat with you about this option and your own implementation. Maybe you could drop me an email? __________________ Hans Bihs Team REEF3D www.reef3d.com

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Residuals and forces spiraling out of control before failing	edomalley1	OpenFOAM Running, Solving & CFD	3	September 7, 2018 11:42
Post processing - Wall shear stress	Carlo	Siemens	1	March 4, 2009 08:35
non-linear analysis of floating bodies	Dr.K.Thiruvenkatasamy	Siemens	0	April 19, 2006 04:40
shear stress scalar definitions?	Novak Elliott	CFX	0	April 6, 2003 02:45
What is the detail definition of wall shear stress	zjm	FLUENT	0	January 2, 2002 08:43

October 22, 2024, 13:59		#3
KevinMcTaggart New Member Kevin McTaggart Join Date: May 2018 Posts: 15 Rep Power: 8	Hello Hans. I emailed you and look forward to discussing further. My impression is that the computation of the flow field is working well, and that accurate evaluation of shear forces will require moderate effort. Kevin