Setting Up Mass Flow Rate of DPM Point Injection — Lesson 3

How do you set up the mass flow rate of DPM point injection in 2D and in 2D axisymmetric in Fluent software?

The manual explains the difference between 2D axisymmetric and 2D non-axisymmetric.

2D non-axisymmetric: The model will consider that your injection (which will have the form of a slot, or a collection of injection points on a line of 1 meter long) is 1 meter long in the third dimension. This implies that if your device is 0.25 m in the nonsimulated dimension, you will have to use a mass flow rate 4 times higher (x kg/s per 0.25 m = 4x kg/s per meter).

2D axisymmetric: Per 2π radians also means per 360 degrees, or for the entire circle. In this case, Fluent software will assume that your injection is a circle of 360 degrees, i.e., a collection of injection points along a circle. For example, if you define an injection point at x = 0, y = 0.5 m (where z is the axis of revolution) with a mass flow rate of 1 kg/s, you will actually be modeling an injection that is a circle of radius 0.5 and center x = z = y = 0.0 and a mass flow rate of 1 kg/s.

In conclusion, if you are modeling this type of injection (a circle), then you do not have to divide your mass flow rate.

If your problem (in 3D) only has one injection point, then there is no problem because this is not an axisymmetric problem and does not need to be modeled in 3D.