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-   -   So many questions in DPM & UDF - Help! URGENT! (http://www.cfd-online.com/Forums/fluent/50758-so-many-questions-dpm-udf-help-urgent.html)

Prashanth March 3, 2009 23:26

So many questions in DPM & UDF - Help! URGENT!
 
Hi All

This will be a long post as I have so many questions regarding DPM model and UDF's. I'm working towards a close deadline and hence decided to post all questions together. Sorry for the trouble.

1) My geometry has the flow and particle inlet at a certain distance from the point (0,0,0) - center of my whole geometry in the positive Z direction. To be precise, the center of my inlet's co-ordinates are (0, 0, 0.0381). For the first and last point of the group injection, I tried giving co-ordinates with respect to the center of my domain but I lost all particles. Now, when I give the initial and final point with respect to the center of my inlet, it works. Is this right?

2) Do I have to divide the total particle mass flow rate by the no of particle streams to get the mass flow rate to be input in the first and last point columns in a group injection?

3) How do I get the total mass of particles injected into the domain? I read some previous posts but not sure about the macro to be used for this.

4) This is probably where I'm so in doubt. My UDF was giving a segmentation error and also generating a message saying 'Stack Backtrace Generated'. I read in some posts that reading the case and data file, defining no. of UDM's, initializing the solution once, compiling the UDF and then running the particle tracks works. It worked for me too and I have some answer even though it is way off. Is this method right? Doesn't initializing the solution make the flow field variables to go to zero?

5) I tried just allocating and initializing my UDM's. I read in the case file, specify no of UDMs in GUI, Compile my UDF, Hook up my ON_DEMAND macro and then tried to initialize the solution & then load data file. But this results in a bug as follows:

Stack backtrace generated for process id 1462 on signal 1 : Please include this information with any bug report you file on this issue!

Error: fluent.6.3.33 received a fatal signal (SEGMENTATION VIOLATION).

When I load my case and data file together, specify no. of UDM's, compile and then hook up macros, it hooks up fine. Why is this?


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