# KR521: How to setup the mass flow rate of DPM point injection in 2D and in 2D Axisymmetic in ANSYS FLUENT?

 The manual explains the difference between 2D axisymmetric and 2D non-axisymmetric.2D non-axi-symmetric: the model will consider that your injection (which will have the form of a slot - collection of injections points on a line of a meter long) is 1 meter long in the 3rd dimension. This implies that if your device is 0.,25 m in the non-simulated 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 axi-symmetric: per 2pi radiant also means per 360 degree or for the entire circle. In this case, FLUENT 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 (z is the axis of revolution) with a mass flow rate of 1 kg/s, you will actually be modeling an injection which 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 1 injection point, then there is no problem because this is not an axisymmetric problem and need to be modelled in 3D.

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