Tangential velocity

July 12, 2006, 10:35

How does fluent calculate the Tangential Velocity? I mean is the SQRT(Vx^2 + Vy^2)? or does it use another way? kind regards, Jan

July 12, 2006, 12:11

That would give you the magnitude in the X Y plane... assuming that your axis is the Z-axis, this would be the combination of the Radial and Tangential components...

Again, assuming the Z-axis as your axis of rotation, then Tangential would be Vx*cos(theta)-Vy*sin(theta) and Radial would be Vx*sin(theta)+Vy*cos(theta).

You have to tell Fluent what your reference axis is. This is in the Define->Boundary Conditions... Select the Fluid volume... here you can define the axis origin and direction. The equations will change depending on the location and direction of the axis, so what I gave above is stricly for an axis of rotation coincident with the Z-Axis.

Hope this helps, and good luck, Jason

vaqif · August 1, 2018, 17:06

hi,
I am modeling a fan by using Fluent fan boundary condition. Also, I have defined polynomial tangential velocity in swirl specification. After iterating, I can not get the same profile that I defined first. Even, when I give constant tangential velocity magnitude, I can not obtain the same velocity when I draw the xy plot.

I am wondering maybe my definition from tangential velocity is different than fluent!

could you help me

July 12, 2006, 10:35	Tangential velocity	#1
Jan Guest Posts: n/a	How does fluent calculate the Tangential Velocity? I mean is the SQRT(Vx^2 + Vy^2)? or does it use another way? kind regards, Jan

July 12, 2006, 12:11	Re: Tangential velocity	#2
Jason Guest Posts: n/a	That would give you the magnitude in the X Y plane... assuming that your axis is the Z-axis, this would be the combination of the Radial and Tangential components... Again, assuming the Z-axis as your axis of rotation, then Tangential would be Vxcos(theta)-Vysin(theta) and Radial would be Vxsin(theta)+Vycos(theta). You have to tell Fluent what your reference axis is. This is in the Define->Boundary Conditions... Select the Fluid volume... here you can define the axis origin and direction. The equations will change depending on the location and direction of the axis, so what I gave above is stricly for an axis of rotation coincident with the Z-Axis. Hope this helps, and good luck, Jason

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August 1, 2018, 17:06		#3
vaqif New Member vaqif Join Date: Jun 2017 Posts: 3 Rep Power: 9	hi, I am modeling a fan by using Fluent fan boundary condition. Also, I have defined polynomial tangential velocity in swirl specification. After iterating, I can not get the same profile that I defined first. Even, when I give constant tangential velocity magnitude, I can not obtain the same velocity when I draw the xy plot. I am wondering maybe my definition from tangential velocity is different than fluent! could you help me