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Why flow appears on suction side of the blade in simulation?

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Old   May 7, 2020, 14:15
Default Why flow appears on suction side of the blade in simulation?
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Hi,

I am running the simulation for a wind turbine blade using implicit unsteady solver. As inflow direction is along z-axis, but in the reference coordinate system Z is pointing opposite to the inlet therefore I described the flow direction [0,0,-1] and kept the positive inlet velocity ''+x'' m/s.

However, for drag force and drag coefficient the direction is [0,0,1].
For the moment coefficient, direction is [0,0,-1]
For the rotation rate, in moving reference frame axis direction is: [0,0,1] and rotational speed is kept ''-x m/s'' considering clockwise rotation.

The simulation is converged, but the flow appears on suction side of the blade instead of pressure side, consequently flow is not attached along the blade. It can be seen from the plot of iso-contours of Q criterion (left) whereas the coordinate system is also shown on the right.

Can anyone please tell why is it happening?
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Old   May 10, 2020, 12:44
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Hello again =D

The problem is perhaps the direction you assigned at the inlet. As a default, the flow velocity will be normal to the surface (velocity inlet). Maybe the direction you assigned reverses the flow? Try to revert back the default setting.
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Old   May 10, 2020, 12:50
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Quote:
Originally Posted by SimulatorMaster View Post
Hello again =D

The problem is perhaps the direction you assigned at the inlet. As a default, the flow velocity will be normal to the surface (velocity inlet). Maybe the direction you assigned reverses the flow? Try to revert back the default setting.
If you look at the picture on the right showing coordinate system Z-axis is pointing opposite to the inlet. However, my flow direction is along Z-axis, so according to the coordinate system I mentioned the flow direction [0,0,-1].

Whereas, the blade is aligned with Y-axis, thus rotates in X-Y plane.
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