Particle Injection Flow Rate [kg/m2-s]

Manathan · May 4, 2015, 11:49

Hello everyone,

I would like to know how to get the injection flow rate for each particle meaning that I put in INPUT the mass flow rate [kg/s] but I need to obtain its value normalized by an area in the same way the udf "DPM_EROSION" macro does : mdot/face_area .

Since I'm simulating 2D axisymmetric, the face_area of this udf is unclear for this case. And therefore the area I should use at injection is also unclear.

Thank you !

`e` · May 4, 2015, 19:31

If each particle of an injection stream has a unique mass flow rate you may need to inject your particles using a file instead of the other options such as from a surface or line.

If you're simulating in 2-D then you could use a length of 1 m in the third direction.

Manathan · May 5, 2015, 04:09

mmm since I'm using a linear space repartition, i thought that using a linear distribution of the mass flow rate would be sufficient.
I'll try to do that then, thank you. Also in 2D axisymmetric, I think I've discovered that the DPM_EROSION macro gives the flow rate : mdot/area with an area for 1 radian. So I thought that I would use for the area of each stream in position r the following equation :

mass flow rate = flow rate * (2*r*dr)

with dr being half the distance between each stream. This area correspond to 1 radian.

I don't have the time to check right now, so if someone knows if it's true it would be great, otherwise I will post my results later on.

May 4, 2015, 11:49	Particle Injection Flow Rate [kg/m2-s]	#1
Manathan New Member Join Date: Apr 2015 Posts: 28 Rep Power: 11	Hello everyone, I would like to know how to get the injection flow rate for each particle meaning that I put in INPUT the mass flow rate [kg/s] but I need to obtain its value normalized by an area in the same way the udf "DPM_EROSION" macro does : mdot/face_area . Since I'm simulating 2D axisymmetric, the face_area of this udf is unclear for this case. And therefore the area I should use at injection is also unclear. Thank you !

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May 4, 2015, 19:31		#2
`e` Senior Member Join Date: Mar 2015 Posts: 892 Rep Power: 18	If each particle of an injection stream has a unique mass flow rate you may need to inject your particles using a file instead of the other options such as from a surface or line. If you're simulating in 2-D then you could use a length of 1 m in the third direction.

May 5, 2015, 04:09		#3
Manathan New Member Join Date: Apr 2015 Posts: 28 Rep Power: 11	mmm since I'm using a linear space repartition, i thought that using a linear distribution of the mass flow rate would be sufficient. I'll try to do that then, thank you. Also in 2D axisymmetric, I think I've discovered that the DPM_EROSION macro gives the flow rate : mdot/area with an area for 1 radian. So I thought that I would use for the area of each stream in position r the following equation : mass flow rate = flow rate * (2rdr) with dr being half the distance between each stream. This area correspond to 1 radian. I don't have the time to check right now, so if someone knows if it's true it would be great, otherwise I will post my results later on.