Number of particle positions in Lagrangian model

February 11, 2008, 21:11

Hi,

I want to use Lagrangian model for particle tracking in Transient simulation using one way coupling in between solid particles and fluid. Hence solid particles will be insterted at the last time step.

I have to specify 'Number of Positions' of the these particles and one option given in CFX-Pre allows to set particles per second(called 'Direct Specification'). Suppose I want to track 1000 particles at once, then, do I need to divide it by my time step (say 0.0001 sec) in order to get sensible number of particles per second? I am worried if I mention 1000 particles and if solver divides it by time step then only one particle will be tracked. If it does not calculate that way then I should not specify 1000/(time step).

Please help.

Thanks, KK

February 12, 2008, 06:08

Hello KK,

don't think that the number of particle is divided by your timestep.

Regards

Elisabetta

February 12, 2008, 15:31

Thank you very much Elisabetta, I specified 10^5 partciles under 'Direct Specification' (CFX-Pres shows unit to be per second) and my time step was 0.0002 seconds. I noticed that the solver was injecting 20 particles per time step. That makes sense that total number of particles injected in one second would be 10^5. is it correct?

February 13, 2008, 06:33

Yes I think it is correct.

Ciao

Elisabetta

February 16, 2008, 05:56

February 11, 2008, 21:11	Number of particle positions in Lagrangian model	#1
KK Guest Posts: n/a	Hi, I want to use Lagrangian model for particle tracking in Transient simulation using one way coupling in between solid particles and fluid. Hence solid particles will be insterted at the last time step. I have to specify 'Number of Positions' of the these particles and one option given in CFX-Pre allows to set particles per second(called 'Direct Specification'). Suppose I want to track 1000 particles at once, then, do I need to divide it by my time step (say 0.0001 sec) in order to get sensible number of particles per second? I am worried if I mention 1000 particles and if solver divides it by time step then only one particle will be tracked. If it does not calculate that way then I should not specify 1000/(time step). Please help. Thanks, KK

February 12, 2008, 06:08	Re: Number of particle positions in Lagrangian mod	#2
Elisabetta Guest Posts: n/a	Hello KK, don't think that the number of particle is divided by your timestep. Regards Elisabetta

February 12, 2008, 15:31	Re: Number of particle positions in Lagrangian mod	#3
KK Guest Posts: n/a	Thank you very much Elisabetta, I specified 10^5 partciles under 'Direct Specification' (CFX-Pres shows unit to be per second) and my time step was 0.0002 seconds. I noticed that the solver was injecting 20 particles per time step. That makes sense that total number of particles injected in one second would be 10^5. is it correct?

February 13, 2008, 06:33	Re: Number of particle positions in Lagrangian mod	#4
Elisabetta Guest Posts: n/a	Yes I think it is correct. Ciao Elisabetta

February 16, 2008, 05:56	Re: Number of particle positions in Lagrangian mod NM	#5
Roghayyeh Motallebzadeh Guest Posts: n/a

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