I am using Fluent to simulate Spray injection. I have a aproblem in applying variable mass flow rate & velocity in injection definitions menu. I have been trying to use a UDF for DEFINE_DPM_INJECTION_INIT. But I could not find any clear information about using this UDF for this case in the manuals. If you have ever done this before or you have a sample of this UDF it would be greatly appreciated if you kindly help me.