CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   CFX (http://www.cfd-online.com/Forums/cfx/)
-   -   Flow Direction: normal to boundary!!! (http://www.cfd-online.com/Forums/cfx/24179-flow-direction-normal-boundary.html)

 Atit June 26, 2007 06:48

Flow Direction: normal to boundary!!!

My current simulation is the flow between circular flat plate(both plates lie parallel to X-Z plane). The continuous flow of air flows in radially from the perimeter towards the center of the plate where there is the outlet. I specified 'INLET' with zero total pressure, flow direction: normal to boundary condition, and static temp=308K at the inlet position of the domain.

After the computation, I found in CFX-Post that there is the Y-component of velocity at the inlet surface. This could not be possible, couldn't it? 'cause Y axis lie parallel to the inlet surface!!!

Then I change the flow direction at inlet position in CFX-Pre to that

FLOW DIRECTION:

Option = Cylindrical Components

Unit Vector Axial Component = 0

Unit Vector Theta Component = 0

Unit Vector r Component = 1

AXIS DEFINITION:

Option = Coordinate Axis

Rotation Axis = Coord 0.2 (this is Y axis)

However I still have the Y-component of velocity at the inlet surface.

Do anybody know what wrong with this? Does 'flow direction: normal to boundary' really mean that there must be no flow in parallel direction of the surface?