# Change axis rotation of MRFZone

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

 November 17, 2011, 01:30 Change axis rotation of MRFZone #1 Member   ThanhToan Join Date: Sep 2010 Posts: 49 Rep Power: 14 Hi expert, Now I am simulating aerodynamic of wind turbine. I should use MRFs function to define rotation speed of it. However, My problem is so difficult due to rotation axis which will be assumed to change dependent with time. I mean rotation axis is not X, Y, or Z axis, conventionally. May I write code to change it with dependent time? Is it possible? I need some advice to solve above problem. I really appreciate your help. Tran

 November 17, 2011, 06:15 #2 New Member   Wei Zhao Join Date: Mar 2010 Posts: 28 Rep Power: 14 what do u mean? u want to change the rotation axis only, or change the whole set-up (including the boundary, rotational axis, and even the grid configuration)?

November 17, 2011, 06:40
#3
Member

ThanhToan
Join Date: Sep 2010
Posts: 49
Rep Power: 14
Hi Zhao,

Generally, we define X-axis, or Y-axis, or Z-axis for rotation axis (For instance, vector [0 0 1] is defined for Z-rotation axis). However, I want to define axis rotation which depends on time as follow function:
axis rotation = [x(t) y(t) z(t)]
x(t), y(t) and z(t) is function of variable x with dependent time.

Best regards,
Tran

Quote:
 Originally Posted by zhaowei what do u mean? u want to change the rotation axis only, or change the whole set-up (including the boundary, rotational axis, and even the grid configuration)?

November 17, 2011, 08:05
#4
New Member

Wei Zhao
Join Date: Mar 2010
Posts: 28
Rep Power: 14
Quote:
 Originally Posted by trantoan2008 Hi Zhao, Thank your for your quickly response. Generally, we define X-axis, or Y-axis, or Z-axis for rotation axis (For instance, vector [0 0 1] is defined for Z-rotation axis). However, I want to define axis rotation which depends on time as follow function: axis rotation = [x(t) y(t) z(t)] x(t), y(t) and z(t) is function of variable x with dependent time. Best regards, Tran
according to your description, i want to know what the "time" mean? what kind of simulation do u want to get? steady state or transient?

i guess u may want something like a pedestal fan, which is a quasi-steady state simulation. that is for each rotation direction, it is a steady state, but generally, the axis is moving. i.e. the movement of the rotation axis is much slower to ensure the flow to reach steady state at each direction. Is that correct? but when u changed the rotation direction, the configuration of grids needs to be adjusted, since the rotation domain should be perpendicular to the rotation axis. this could be very complex, wait for some experts.

November 17, 2011, 08:27
#5
Member

ThanhToan
Join Date: Sep 2010
Posts: 49
Rep Power: 14
Quote:
 Originally Posted by zhaowei according to your description, i want to know what the "time" mean? what kind of simulation do u want to get? steady state or transient? i guess u may want something like a pedestal fan, which is a quasi-steady state simulation. that is for each rotation direction, it is a steady state, but generally, the axis is moving. i.e. the movement of the rotation axis is much slower to ensure the flow to reach steady state at each direction. Is that correct? but when u changed the rotation direction, the configuration of grids needs to be adjusted, since the rotation domain should be perpendicular to the rotation axis. this could be very complex, wait for some experts.
Hi Zhao,

My problem is a transient simulation. When we changed the rotation direction, the configuration of grids needs to be adjusted and the rotation domain should be perpendicular to the rotation axis. I agree with you this point.
For solving rotation zone which must be perpendicular the rotation axis, we may use dynamic mesh technique and GGI technique.

 November 17, 2011, 10:37 #6 New Member   Wei Zhao Join Date: Mar 2010 Posts: 28 Rep Power: 14 wow, sounds not easy. only the ggi has made me frustrating, haha

 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 OffTrackbacks are Off Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post arapha FLUENT 3 November 8, 2016 22:44 phanh FLUENT 0 November 11, 2011 06:22 Mattia FLUENT 4 October 22, 2007 12:05 Michael CFX 15 June 30, 2006 09:01 Dunga CFX 4 May 11, 2003 11:44

All times are GMT -4. The time now is 00:54.