[Shelley]

I want to simulate the oscillating airfoil by using dynamic mesh in time domain. How can I define the motion?

[me3840]

Create a rotating region inside your exterior region. Then create a motion for the rotating region under tools>motion. Define a function (probably some kind of sine wave) for that motion.

[Shelley]

Thank you for reply. How to define a sine wave motion in star com? I can not find the option of UFD. There are only settings for rotation axis, anglar velocity...etc

Originally Posted by me3840

Create a rotating region inside your exterior region. Then create a motion for the rotating region under tools>motion. Define a function (probably some kind of sine wave) for that motion.

[faee0]

may be you can create a transition motion,and create a function to control the motion.

[me3840]

Just type in a function in the field for the rotation rate.

[Shelley]

Thank you so much. Can you give me a sample of function, such as a motion of frequency 10Hz and amplitude -5 to 5 degrees. Or can I find some useful information from the UserGuide? I can not find it so far...

Originally Posted by me3840

Just type in a function in the field for the rotation rate.

[me3840]

Look for the section using tools> using field functions

[Shelley]

I have defined a new field function which named "Motion", the expression is 0.5*sin(2*3.14*$Time). Then I type "$Motion" in rotation rate and got the warning below:

"Error: Unable to compile field function: Motion (Motion)
Cannot resolve function ${time}: "time" not defined."

what does that mean?

Originally Posted by me3840

Look for the section using tools> using field functions

[me3840]

This error is likely because your physics continuum is not set to be unsteady. The function $Time does not exist for steady cases.

Note your field function must return radians/s. Originally you wanted it to turn through some degree sweep - ensure (a) that you are using radians and (b) you differentiate your function so it is a rotation rate.

[Shelley]

i chose the implicit unsteady solver. The new field function including $Time can be created normally. The error showed up when I defined the rotation rate.

Originally Posted by me3840

This error is likely because your physics continuum is not set to be unsteady. The function $Time does not exist for steady cases.

Note your field function must return radians/s. Originally you wanted it to turn through some degree sweep - ensure (a) that you are using radians and (b) you differentiate your function so it is a rotation rate.

[me3840]

Be sure you are using a capital T as well. It worked for me when I tried it.

[Shelley]

Yes, I used a capital T. Do I need a $ and rad/s in rotation rate? Or just the name of field function?

Originally Posted by me3840

Be sure you are using a capital T as well. It worked for me when I tried it.

[me3840]

No, just the $fieldFunctionName.

Go through your field function list and ensure that Time is one of them. If it is not one of your physics continua is set incorrectly.

[datouguaiguai]

HI,how should i creat the rotational region?

[me3840]

Originally Posted by datouguaiguai

HI,how should i creat the rotational region?

datouguaiguai, that is not enough information to be useful. If you're having a problem, please create your own thread.

[Shelley]

It works now. Thank you so much for your help.

Originally Posted by me3840

No, just the $fieldFunctionName.

Go through your field function list and ensure that Time is one of them. If it is not one of your physics continua is set incorrectly.

[jpesich]

Shelley,

Is there a way to make an animation of an airfoil oscillating with the varying velocity distribution shown?