Swirl-Velocity Specification of 2-D Fan Boundary Condition
I opened a relevant thread before at the student community forums of ANSYS but did not find a closure about the subject (i.e. https://studentcommunity.ansys.com/t...ary-condition/ ). I'll appreciate any help from the cfd-online community.
I am defined a 2-D fan model using the fan boundary condition on a square surface in a 3-D simulation of a room. I am puzzled by how Fluent interprets the tangential velocity since the tangential velocity I get as a result is always less than what I input, and typically half of the constant value I input as tangential velocity (i.e. when I use values on the order of axial velocity). The results below correspond to the case with a constant tangential velocity of 1 m/s. According to the plot of tangential velocity as a function of y direction along the midline of the fan surface, the values plateaued at around 0.5 m/s outside hub (half of the input). How should I interpret this? https://studentcommunity.ansys.com/c...&upscale=false https://studentcommunity.ansys.com/c...&upscale=false I'll greatly appreciate your help in clarifying how Fluent uses inputs for tangential velocity in the 2-D fan boundary condition? Why don't I see the tangential velocity imposed between the hub radius and outer dimension of the boundary surface as I define? Is there a physical reasoning behind this? |
Which boundary condition are you using? Fluent doesn't have a "fan boundary condition" Just post a screenshot of your boundary condition input.
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Any help from the community would be appreciated.
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Can you check velocities slightly downstream/upstream of the fan surface?
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2. X velocity 3. Z velocity at the velocity inlet and fan bc |
OK, but can you change the contour plane to another plane that is slightly downstream/upstream of the fan plane? Like, 5mm away from the fan.
Also, why do you have a velocity inlet BC? Quote:
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Attached are contours for 5mm upstream, fan and 5mm downstream with the same scale. Thanks |
So, the max. velocity 5mm downstream is higher than max. velocity on fan plane, right?
Can you find a plane with the velocity value that you input (1m/s I guess)? Try to turn OFF the node values. Quote:
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I don't know how the BC works, and couldn't find any explanation on the theory/user guide. But there might be an averaging problem, that's why I asked for turned off nodes.
As I understand, this is not a "problem" for you, you just wanted to make sure that the fan BC works the way it intended to. Quote:
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