# Dynamic moving reference frame

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 May 1, 2007, 08:23 Dynamic moving reference frame #1 Peter Wilkins Guest   Posts: n/a Sponsored Links Hi all, I'm modelling a rotating wing using a moving reference frame. I can do this easily for a constant speed rotation, but is there a way of using the same technique for an accelerating wing? I can't see a way to use a UDF to define the rotational speed of my MRF. Thanks, Peter mina likes this.

 May 1, 2007, 09:11 Re: Dynamic moving reference frame #2 Hussein Guest   Posts: n/a Hello , I am also modeling a rotating wing using a moving reference frame , f u want we can be in contact in case some of us need help ? if yes , let me know

 May 1, 2007, 09:15 Re: Dynamic moving reference frame #3 Peter Wilkins Guest   Posts: n/a Sure. I am able to model a wing rotating at constant angular velocity but I want to model a wing which is rotating at an increasing rate. Any ideas? Peter

 May 1, 2007, 09:37 Re: Dynamic moving reference frame #4 Hussein Guest   Posts: n/a I trhink in the User defined functions UDF is the best way , frankly i am not so good in UDF , However the main idea behind the function should be , increasing at a constant rate or increasing arbitrarily , personaaly i prefer workin on c . I did my work on a constant speed rotation as a first step , but i didn it on a "Bad Wing" . now i have to do it again with a NACA 0015 . is that good ? also , i had an idea about drawing the Wing as a 3d dimensions , i thought that the best method to draw it is to , import the vertex of a 2d airfoil , then tryin to convert this 2d into 3d through the addition of many 2 airfoils then joinnig them . I am not sure about drawing a naca 0015 as a 3dimensin since i worked on a arbitrarily 3 dimension wing . any idea of drawing ?

 May 2, 2007, 07:10 Re: Dynamic moving reference frame #5 Phil Guest   Posts: n/a But are you using the unsteady solver as you will need to with an accelerating component? Sliding meshes are the best way. - Unsure whether you need a UDF to do this, but you could simply SET THE ROTATIONAL SPEED TO INCREASE WITH EACH TIME STEP. I have no real experience in this specific case but I would have thought this was the only way to do it.

 May 3, 2007, 04:39 Re: Dynamic moving reference frame #6 Peter Wilkins Guest   Posts: n/a Phil, Yes I am using an unsteady solver. I could manually increase the rotational speed with each time step but I wanted to write a UDF so that I could do it more efficiently. Peter

 May 3, 2007, 06:12 Re: Dynamic moving reference frame #7 Phil Guest   Posts: n/a how is your experience with UDF's? there should be a define macro to change boundary conditions at the end of each time step. Use the examples as a reference. If you already know this then sorry I can't help you further unless you're doing combustion.

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