KR522: How to setup a rotating flow when the mass flow inlet boundary condition is used in ANSYS FLUENT?
Below are the 2 steps needed to setup a mass flowinlet with a 30 degrees rotation (or swirl). FIRST STEP: Define the axial direction Before setting the boundary condition, one has to ensure that the 'axial' direction as referred in the boundary condition is correctly setup. The axial direction of your system must be equal to the axial direction as defined by the solver. This direction can be found (and modified) under define > boundary conditions > regions corresponding to a fluidzone. Look for the motion tab for the rotationaxis direction panel: X, Y and Z define the direction of the 'axial direction'. FLUENT Default: 2D: X is the axial direction (i.e. X = 1, Y = 0) 3D: Z is the axial direction (i.e. X = 0, Y = 0 and Z = 1) Once the axial direction is defined, we can go to the second step and define the boundary condition STEP 2: Define the rotation angle We will assume that the radial flow direction is 0. If the angle of swirl is 30 degrees, we have an axial component Vx = V * cos(30) and a tangential component Vtheta = V * sin(30). Hence, the input should be the following: Coordinate system: cylindrical Radial Component of Flow Direction: 0 Tangential Component of Flow Direction: sin(30) (enter 0.5) Axial Component of Flow Direction: cos(30) (enter 0.866) 

