CFD Online Discussion Forums

CFD Online Discussion Forums (http://www.cfd-online.com/Forums/)
-   Fluent UDF and Scheme Programming (http://www.cfd-online.com/Forums/fluent-udf/)
-   -   Inconsistency in DPM concentration (http://www.cfd-online.com/Forums/fluent-udf/109348-inconsistency-dpm-concentration.html)

Mat_fr November 15, 2012 09:28

Inconsistency in DPM concentration
 
Dear all,

I'm using the DPM model of FLUENT, with the following parameters :
* unsteady
* two-way coupling (but without resolving the flow equations. Thus, im only resolving the particles motion equation in a one way coupling approach)
* inert particles (no mass, no heat, transfers)

In this context, I was monitoring the DPM_CONCENTRATION average on a surface, and I saw some inconsistencies.

Thus, I did a small test, by computing the total mass of particles in my domain (sum over all the cells of DPM_CONCENTRATION*CELL_VOLUME), and I get the following results :

at injection : mtot = 5.44e-10 kg
after 1s : mtot = 5.29e-10 kg
after 3s : mtot = 4.72e-10 kg
after 5s : mtot = 5.0e-10 kg
What is happening ??? Ok there can be some numerical diffenrences, but not so much!
There are no particles escaping (always the same number as initially), and I don't have any mass transfer. So, what did I miss ?

Thanks a lot for your help !

Best,

Mat

sajeesh April 27, 2013 06:20

[QUOTE=Mat_fr;392284]Dear all,


Thus, I did a small test, by computing the total mass of particles in my domain (sum over all the cells of DPM_CONCENTRATION*CELL_VOLUME), and I get the following results :

at injection : mtot = 5.44e-10 kg
after 1s : mtot = 5.29e-10 kg


sir how you r calculating this.....what is sum over all cells of DPM concentration.how you get that..
what is cell volume
how you get this total mass..
i am fed up with this my problem to finding out the number of particle in my domain...or other wise i want to set a 3 particle in the domain,,how i can do that



Help me please.....


All times are GMT -4. The time now is 15:03.