CFD Online Logo CFD Online URL
www.cfd-online.com
[Sponsors]
Home > Forums > SU2

a small question about rotating frame

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

Reply
 
LinkBack Thread Tools Display Modes
Old   April 27, 2014, 02:56
Default a small question about rotating frame
  #1
New Member
 
JinZhiyi
Join Date: Feb 2014
Posts: 14
Rep Power: 4
JinZhiyi is on a distinguished road
hi,developers and users:

I find a paragraph in your AIAA paper which describe the rotating frame in SU2.

5. Rotating frame and Arbitrary Lagrangian-Eulerian (ALE) formulations

When simulating fluid flow about certain aerodynamic bodies that operate under an imposed steady rotation, including many turbomachinery, propeller, and rotor applications, it can be advantageous to transform the system of flow equations into a reference frame that rotates with the body of interest.19,20,29 With this transformation, a flow field that is unsteady when viewed from the inertial frame can be solved for in a steady manner, and thus more eciently, without the need for grid motion.


You mentioned in the last a steady rotating simulation don't need grid motion.
However, in the rot_caradonna_tung rotating testcase you provide, in the config file:

------------------------ GRID DEFORMATION PARAMETERS ------------------------%
%
% Kind of deformation (NO_DEFORMATION, HICKS_HENNE, PARABOLIC, NACA_4DIGITS,
% DISPLACEMENT, ROTATION, FFD_CONTROL_POINT,
% FFD_DIHEDRAL_ANGLE, FFD_TWIST_ANGLE,
% FFD_ROTATION, FFD_CAMBER, FFD_THICKNESS, FFD_VOLUME)
DV_KIND= FFD_TWIST_ANGLE
%
% Marker of the surface in which we are going apply the shape deformation
DV_MARKER= ( quad_blade, tri_blade )



Why grid deformation still needed?

Tanks in advance.


Jin
JinZhiyi is offline   Reply With Quote

Old   May 15, 2014, 15:21
Default
  #2
New Member
 
Join Date: Dec 2011
Posts: 22
Rep Power: 6
aniketaranake is on a distinguished road
Hi Jin,

You are looking at two quite separate things.

To solve rotating problems, SU2 has implemented the flow equations in the rotating coordinate frame. This formulation, which looks quite like the original flow equations but with additional source terms to account for fictional forces (centrifugal, Coriolis) allows for the steady state solution of problems with a fixed rate of rotation. This is useful for helicopter rotors, propellers, wind turbines, etc.

The option values you are looking at in the config file are related to grid deformation for the purpose of design. A typical problem that these values are used for is for finding the shape of an airfoil to minimize drag at a given lift. SU2 runs successive cases attempting to find such an optimal shape, and as the shape of the airfoil changes it is necessary to deform the grid to match the new shape.

Hope this helps,
Aniket
aniketaranake is offline   Reply With Quote

Reply

Thread Tools
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 On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Boundary conditions for rotating reference frame Borna OpenFOAM 1 August 24, 2011 10:25
Question about N-S eqs. in body fixed noninertial reference frame doctorWho Main CFD Forum 0 July 12, 2011 18:07
Dyanmic mesh + 6DOF + rotating frame xhield FLUENT 0 December 10, 2009 06:02
Rotating reference frame problems DaveG CFX 1 September 8, 2005 16:43
Stack frame size, Origin 2000, fortran, a question. Sergei Chernyshenko Main CFD Forum 4 February 22, 1999 15:24


All times are GMT -4. The time now is 23:38.