Hi all,
Sometimes the fix particledistribution doesn't work properly, it only inserts the bigger particle. I was changing some values like massrate, extrude_length, velocity, insertion face, and other, in order to insert all type of the particles that I want. I managed to do it using trial and error, but I don't think that is the best way. So I have two questions:
is there any other way solve this? please show me your method
what does the key seed in fix insert/stream? I've read it in the manual but there is not no too mush information about it.
I think it is important to say I had the problem of the particles even when the warning message didn't appear
WARNING: Particle insertion: Less insertions than requested (fix_insert.cpp:594)
Thanks in advance
cstoltz | Tue, 05/07/2013 - 03:37
Sounds like your setup is
Sounds like your setup is such that you're not adding a lot of mass and you have a wide particle size distribution. As a result, you may be able to fill up the net desired mass with only 1-2 large particles. You should be able to count up the net desired number of large particles based on total desired mass and PSD.
Regards,
Chris
g.garate | Wed, 05/08/2013 - 00:11
Thanks Chris,
Thanks Chris,
Could you (or anyone) tell me what the key seed in fix insert/stream does?
Regards
cstoltz | Wed, 05/08/2013 - 03:43
'seed' initializes the random
'seed' initializes the random number generator just like in many other commands. Just set to some positive integer.
Regards,
Chris
pipegaldames | Wed, 05/08/2013 - 22:04
What difference we should
What difference we should have to expect between two identical simulations but different seed value in fix insert/stream ?
cstoltz | Thu, 05/09/2013 - 12:09
Individual particle
Individual particle trajectories will differ, but the overall system behavior should be the same. Think about running the same physical experiment a dozen times - you'll get a dozen similar answers, but there will be some natural variation inherent in the experiment. Same thing here. Run the same simulation a dozen times using different random seeds each time and you should get a dozen similar answers with a bit of variance incorporated.
Regards,
Chris
richti83 | Thu, 05/09/2013 - 21:13
About the first question: I
About the first question: I've had similar problems when I tried to insert a very small massrate (85kg/s) in a small region. The precalculation of insert stream and an extrusion length of 3*d told me it will insert ~200 particles every 1.000 steps.
I got only 75kg/s (measured with the new fix massrate). With try and error I found out that the rounding error is to big with this method for my psd.
A better solution for my case was to set the insertion rate with "insert every" to 10.000 and not to use the extrusion length.
This is a normal behavior because you can only insert an integer number of particles.
ckloss | Tue, 05/14/2013 - 12:56
>>Sometimes the fix
>>Sometimes the fix particledistribution doesn't work properly, it only inserts the bigger particle.
It always inserts the bigger particles first, since then higher volume fractions can be reached.
Then the smaller ones are inserted, provided there is enough space left and the # of tries is not used up
Christoph
rahulsoni | Thu, 02/27/2014 - 15:15
Massrate
I am running a simulation with fix insert/stream command. Following is the command in script.
fix insertion particles insert/stream seed 5330 distributiontemplate pdd1
& verbose yes maxattempt 100 mass INF massrate 1.0 start 1000 overlapcheck yes vel constant 0. 0. -1.0 & insertion_face inface extrude_length 0.4
I have assigned massrate = 1.0 but I really don't know how much actually it is. Simulation script is in SI units but from results I do not get mass insetion any way near to 1.0 kg/second or something like that. Please tell me how much actually it is.....