# MovingWallVelocity Boundary Condition

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 June 8, 2007, 07:11 Hi, I want to simulate a pitc #1 Member   Ralph Join Date: Mar 2009 Posts: 40 Rep Power: 8 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

 June 12, 2007, 05:47 Hi, I want to simulate a pit #2 Member   Ralph Join Date: Mar 2009 Posts: 40 Rep Power: 8 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

 June 12, 2007, 06:05 Hi Ralph, 1) You need the #3 Senior Member   Frank Bos Join Date: Mar 2009 Location: The Netherlands Posts: 338 Rep Power: 9 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 __________________ Frank Bos

 June 12, 2007, 06:47 Thanks a lot Frank. Ralph #4 Member   Ralph Join Date: Mar 2009 Posts: 40 Rep Power: 8 Thanks a lot Frank. Ralph

 January 10, 2012, 11:57 flapping simulation #5 New Member   Malu Join Date: Dec 2011 Posts: 1 Rep Power: 0 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

January 10, 2012, 12:36
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Daniel WEI (老魏)
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Quote:
 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.
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 January 23, 2013, 14:33 #7 Senior Member   Sasan Ghomi Join Date: Sep 2012 Location: Iran - Tehran Posts: 185 Rep Power: 4 Hi every body I did'nt understand what is value(0 0 0) in movingWallVelocity boundry condition????/ Can any one explain???

June 18, 2013, 07:15
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Artur
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Quote:
 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...

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