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-   -   MovingWallVelocity Boundary Condition (http://www.cfd-online.com/Forums/openfoam-solving/59646-movingwallvelocity-boundary-condition.html)

 ralph June 8, 2007 07:11

Hi, I want to simulate a pitc

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 canīt 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 June 12, 2007 05:47

Hi, I want to simulate a pit

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 canīt 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 June 12, 2007 06:05

Hi Ralph, 1) You need the

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 June 12, 2007 06:47

Thanks a lot Frank. Ralph

Thanks a lot Frank.

Ralph

 Malu006 January 10, 2012 11:57

flapping simulation

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 January 10, 2012 12:36

Quote:
 Originally Posted by Malu006 (Post 338658) 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 January 23, 2013 14:33

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

 Artur June 18, 2013 07:15

Quote:
 Originally Posted by sasanghomi (Post 403608) 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...

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