[Arsal]

Hi everyone,

I'm trying to obtain particle deposition in a cell zone. According to the manual, in transient mode, with 'loop(p,I->p_init)', it's possible to loop over the particles. The code below is based on suggestions in this forum. However, I couldn't make it work.

I tried simulating in steady mode as well, using 'loop(p,I->p)'. Only replacing it would result in an increase in particles deposited every iteration. If I remove '+' from the code, I see only one dot in the cell zone, but I expect more particles passing.

Can anyone tell what's wrong with this code?

DEFINE_EXECUTE_AT_END(execute_at_end)
{
     Domain *d = Get_Domain(1);
     Thread *t;
     Thread *t_fluid = Lookup_Thread(d,4);
     Injection *I;
     Particle *p;
     Injection *Ilist = Get_dpm_injections();
     cell_t c;
	
     loop(I, Ilist)
     {
        loop(p,I->p_init)
	{
	   c = TP_CELL(p);
	   t = TP_CELL_THREAD(p); 
	  if (t == t_fluid)
	  {
            C_UDMI(c, t, 0) += TP_MASS(p)/C_VOLUME(c, t);
	    MARK_TP(p, P_FL_REMOVED);
	   }
        } 
     }
}

[AlexanderZ]

I don't have experience in DPM simulations, however
as far as I understand you have a loop over particles
it means, you fill UDMI with information, when you are in particular particle,

if there is no "+' then UDMI will contain information about last particle, which was in cell/thread

[Arsal]

Originally Posted by AlexanderZ

I don't have experience in DPM simulations, however
as far as I understand you have a loop over particles
it means, you fill UDMI with information, when you are in particular particle,

if there is no "+' then UDMI will contain information about last particle, which was in cell/thread

Thank you for your reply. Ok, I understood the problem with the steady mode that only considers the last particle. But I can't get my head around why only one cell had a value. I guess it can only be solved in transient mode?

In transient, my expectation is that the code gets the list of 'Injections', which is only one in my case. It starts the loop and gets their current cell and thread. If they are located in the target thread (cell zone), it calculates the concentration (mas divided by volume) and stores it in the UDMI for that cell. And, with 'MARK_TP(p, P_FL_REMOVED)' ends the trajectory of that particle. Do you see some mistake with my logic?

I can see that 'loop(p,I->p_init)' is used in section 2.5.6.4 of the manual with 'DEFINE_DPM_INJECTION_INIT'. So, my guess was that I might need to add something to make it work in 'DEFINE_EXECUTE_AT_END'? Or is it about DPM iteration?

[AlexanderZ]

it should work in steady state as well.

you have a loop over particles, number of particles could be higher than number of cells in domain -> in one cell there could be several particles -> so you need + (C_UDMI(c, t, 0) += TP_MASS(p)/C_VOLUME(c, t); )

I think you need +

[Arsal]

Originally Posted by AlexanderZ

it should work in steady state as well.

you have a loop over particles, number of particles could be higher than number of cells in domain -> in one cell there could be several particles -> so you need + (C_UDMI(c, t, 0) += TP_MASS(p)/C_VOLUME(c, t); )

I think you need +

Thanks. The solution in steady is to use TP_FLOW_RATE(p), which considers all the particles in that stream.

Something else that I haven't been able to find in this forum is how to do discrete steady simulations (instead of a long transient one) that each simulation depends on the previous one. The challenge is how to retain the values of the UDM so that it is used in the next run as an initial profile.

I have thought of using the DEFINE_RW_FILE (or DEFINE_ON_DEMAND?) to write to a file at the end of a simulation. But, I don't know the structure that data needs to be saved with fprintf() so that it can be stored in a UDM later. Any ideas?

[AlexanderZ]

I think, you may try to write to file your UDMs

it doesn't really metter, which macro you will use: define on demand, define adjust or any other