Fluids

How to create a flapping motion on fluent?

• Nishanth
Subscriber

I want to create a flapping motion for a wing on fluent. similar the link attached below, but not that complicated, I just want it to go up and down with the same angle of attack.

https://www.ansys.com/blog/dragonfly-flapping-ansys/

This is the model I have created, it has a enclosure and a rotating wall which contains the wing.

The mesh has a max skewness of 0.89

Lets say I want the wing to go from -60 degrees to +60 degrees, how do I do that?

Should I do this with dynamic mesh or use mesh motion in cell zone conditions?

I have never used UDF, can you please guide me from start on how to simulate the above mentioned motion?

• Rob
Ansys Employee

If it's a simple rotation then you can use sliding mesh and rotate the cylindrical zone.  The input is a rotation speed so you may need to use the expressions in 2019R2 to control the position/angle.

• Nishanth
Subscriber

If it's a simple rotation then you can use sliding mesh and rotate the cylindrical zone.  The input is a rotation speed so you may need to use the expressions in 2019R2 to control the position/angle.

But when I give rotation It is going to rotate in one direction (clockwise or anticlockwise), I want it to go upto a certain angle and then it should start rotating in the other direction. Similar to a bird flapping!

• DucNguyen
Subscriber

dear Rwoolhou

Where can I find this expresstions?

I'm trying simulation the flapping wing. I set up the wing flap down. when it at the bottom, I stop caculate and change the direction of rotation and repeat

sorry for my English

• Rob
Ansys Employee

Expressions are in Fluent 2019Rx (I'd advise using R3, current release). Alternatively you'll need a UDF for rotation speed/direction.