[ralph]

Hi,
I want to simulate a pitching airfoil.
My question is about the boundary conditions.

1) As there is a non constant velocity of the wall along the airfoil, I can´t use the fixedValue boundary condition.
Is the following boundary condition applicable for U?
AIRFOIL
{
type movingWallVelocity;
value uniform (0 0 0);
}

Does it mean, that there is a zero relative velocity forced at the wall?

2) Can I leave the boundary conditions for all other variables as they are in the case with non-moving walls?

Ralph

[ralph]

Hi,
I want to simulate a pitching airfoil.
My question is about the boundary conditions.

1) As there is a non constant velocity of the wall along the airfoil, I can´t use the fixedValue boundary condition.
Is the following boundary condition applicable for U?
AIRFOIL
{
type movingWallVelocity;
value uniform (0 0 0);
}

Does it mean, that there is a zero relative velocity forced at the wall?

2) Can I leave the boundary conditions for all other variables as they are in the case with non-moving walls?

Ralph

[lr103476]

Hi Ralph,

1) You need the movingWallVelocity boundary condition for U on the moving wall. This boundary condition corrects the flux due to mesh motion in such a way that the total flux phi through the moving wall is zero. The way it should be the case, you can check phi in the time dirs.

2) When you are using icoDyMFoam, you only have motionU, U and p. Leave p and the rest of U like in case of nonmoving wall. In motionU define the motion of the wall by applying the oscillationFixedValue BC, or take fixedValue (0 0 0) when the motion of the wall is defined by using a dynamicFvMesh lib. To be safe, take fixedValue (0 0 0) on all outer boundaries, except the symmetry and empty patches. If you dont take fixedValue, but zeroGradient on the inlet, it might move with the flow....Also nice, but you dont want that :-)

Goodluck,
Frank

[ralph]

Thanks a lot Frank.

Ralph

[Malu006]

hey everyone, i was also stuck at simulating a pitching airfoil simulation, finally i was able to do so uisng sixDoFRigidBodyDisplacement. now i have to add a heaving motion along with the pitching motion. i first tried to do so it by changing the constraints (fixed axis and fixed line), but this did not work. does anyone have an idea about how to go about this?

Thanks
Malu

[lakeat]

Originally Posted by Malu006

hey everyone, i was also stuck at simulating a pitching airfoil simulation, finally i was able to do so uisng sixDoFRigidBodyDisplacement. now i have to add a heaving motion along with the pitching motion. i first tried to do so it by changing the constraints (fixed axis and fixed line), but this did not work. does anyone have an idea about how to go about this?

Thanks
Malu

It will work. I've been using it for a long time, just be careful about the directions settings. Reexamine and Retry.

[sasanghomi]

Hi every body
I did'nt understand what is value(0 0 0) in movingWallVelocity boundry condition????/
Can any one explain???

[Artur]

Originally Posted by sasanghomi

Hi every body
I did'nt understand what is value(0 0 0) in movingWallVelocity boundry condition????/
Can any one explain???

I think it's equivalent to the no-slip condition for a standard wall-type patch except here it refers to a moving one...

[saurabhshubham]

hi everyone.

I am using the same code for the case of heaving airfoil as I did use for transverse oscillating cylinder.
but when I am checking the velocity at the tip of the airfoil at t=0, then the value is not zero, as in case of oscillating cylinder case.
even after running it for few seconds the vorticity contours starts originating from the front of the airfoil.

[CHAYANIT]

Originally Posted by Malu006

hey everyone, i was also stuck at simulating a pitching airfoil simulation, finally i was able to do so uisng sixDoFRigidBodyDisplacement. now i have to add a heaving motion along with the pitching motion. i first tried to do so it by changing the constraints (fixed axis and fixed line), but this did not work. does anyone have an idea about how to go about this?

Thanks
Malu

I am struck in piching airfoil case. Can you help me in this case??