You need to loop over all the particles:

loop(p,Inj->p){

c = P_CELL(p);

ct = P_CELL_THREAD(p);

}

c and ct will be the pointers correspond to the cell of the current particle (i.e. the cell which contains the current particle), then you can use these pointers to call the flow variables at that specific cell.

Have a look of this:

http://www.cfd-online.com/Forums/fluent-udf/43577-dpm-udf-loop-over-all-particles.html

Thanx for the link, however I have already seen it. I thought that maybe someone knows macro or command to get number of particles in each cell. In calculation performed in unsteady state we can see in fluent number of particles in cells it means that Fluent already count this. In steady state simulation this option disappear.In manual I found only DPM_CONCENTRATION which gives value kg/m3.

But maybe it is necessary to create own loop for all stream...

Hi Maciej,

I never used the DPM macros, but if you get the particle concentration with the C_DPMS_CONCENTRATION macro (found it in the latest UDF manual from Fluent, too) and you know the density and size of your particles, it should be straight-forward to calculate the particle number: just divide the concentration from the DPM macro by the (average) mass of your particles and you get the number of particles per liquid volume. If you need the number of particles per cell it should be possible to use the C_Volume(c,t) macro.

This is just an educated guess, since I don't have a running solution for this, but it may help...

Regards,

Stephan

Hi Stephen, I solved problem in the same method that you write. I'm simulating spray dryers so inside the domain there are particles with different size and mass. However I determined number of particle based on average properties of particles. Number is not precisely but allows me to estimate number of particles in cell. Additionally I'm trying to write other macro witch allows to sum up all particles by loop.

Thanx once again for advice.

Best regards,

Maciej

Dear Maciej，

I also now need this parameter for DPM,i am using unsteady simulation.How did u calculate this parameter? Please kindly share with me.

Best wishes,

Fangfang Sun

You need to loop over all the particles:

loop(p,Inj->p){

c = P_CELL(p);

ct = P_CELL_THREAD(p);

}

c and ct will be the pointers correspond to the cell of the current particle (i.e. the cell which contains the current particle), then you can use these pointers to call the flow variables at that specific cell.

dear sir,

so can you explain little bit more.  I understand that you point to the cel where the particle are.

so I want to used the number of particle in each cel to calculate the absorption coefficient (MIe theory)

if possible directly give the absorption coefficient to fluent

else calculate a source term and give it back to the cell

can you please explain how I could get it please if possible in steps because i'm new with UDF

DEFINE_SOURCE(energy,c,t,ds,eqn)

{

/*FILE *fp;*/

real source,tep,sigma,Pamb,tamb;

real MW[18];

real Xh2o,Xco,Xco2,Xch4,ph2o,pco,pco2,pch4;

real MWmix,sum=0;

real kapa,absh2o,absco,absco2,absch4;

real a0,a1,a2,a3,a4,a5;

real b0,b1,b2,b3,b4,b5;

real c0,c1,c2,c3,c4;

real d0,d1,d2,d3,d4;

int i;

/*fp=fopen("properties.txt","w");*/

tep=C_T(c,t);

MW[0]=1;

MW[1]=32;

MW[2]=17;

MW[3]=16;

MW[4]=2;

MW[5]=18;

MW[6]=33;

MW[7]=28;

MW[8]=44;

MW[9]=16;

MW[10]=15;

MW[11]=14;

MW[12]=30;

MW[13]=29;

MW[14]=31;

MW[15]=34;

MW[16]=13;

MW[17]=28;

sigma=0.000000056697;

Pamb=1.0;

tamb=298.0;

a0=18.741;

a1=-121.310;

a2=273.500;

a3=-194.05;

a4=56.31;

a5=-5.8169;

b0=-0.23093;

b1=1.12393;

b2=9.4153;

b3=-2.99880;

b4=0.51382;

b5=-.000018684;

c0=6.6334;

c1=-0.0035686;

c2=0.000000016682;

c3=0.00000000025611;

c4=-0.000000000000026558;

if(tep750)

{

d0=10.09;

d1=-0.01183;

d2=0.0000047753;

d3=-0.000000000587209;

d4=-0.000000000000025334;

}

for(i=0;i

I want to calculate the void fraction i.e.

void fraction = (cell_vol - summation(dia_i * Vol_i))/cell_vol.

Any possible help will be appreciated.