Time step of steady particle tracking

payam_IUST · October 10, 2009, 16:38

Hi
I am using steady particle tracking and then generate step by step file to see positions of particle at evrey time step.unfortunately the time step that fluent considers is very small(ebout 1e-6) and I want to change it(to about 1e-2),but however I change length scale or step length,the time step does not chang effectively,I even examined this udf to change time step :

#include "udf.h"
#include "dpm.h"

DEFINE_DPM_TIMESTEP(PAYAM,p,dt)
{
return 0.1;
return dt
}

but nothing changes!
Anyone can help me?

Andrej · October 12, 2009, 08:19

Probably you can not make time step more , then
length of Cell divided by the Velocity of the particle in cell. CFL Number in Cell can not be more then 1.0.

October 10, 2009, 16:38	Time step of steady particle tracking	#1
payam_IUST New Member Payan Join Date: Oct 2009 Posts: 21 Rep Power: 16	Hi I am using steady particle tracking and then generate step by step file to see positions of particle at evrey time step.unfortunately the time step that fluent considers is very small(ebout 1e-6) and I want to change it(to about 1e-2),but however I change length scale or step length,the time step does not chang effectively,I even examined this udf to change time step : #include "udf.h" #include "dpm.h" DEFINE_DPM_TIMESTEP(PAYAM,p,dt) { return 0.1; return dt } but nothing changes! Anyone can help me?

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October 12, 2009, 08:19		#2
Andrej New Member Join Date: Oct 2009 Posts: 11 Rep Power: 16	Probably you can not make time step more , then length of Cell divided by the Velocity of the particle in cell. CFL Number in Cell can not be more then 1.0.