# Monte Carlo - Number of Iterations?

 Register Blogs Members List Search Today's Posts Mark Forums Read

 January 31, 2007, 17:48 Re: Monte Carlo - Number of Iterations? #2 opaque Guest   Posts: n/a Dear tsimon, The heat exchange between boundaries is recomputed every iteration.. As you said, the statistical nature of MC model will not give you the same results between iterations. You mentioned that %SD is 100%, is is for the surfaces, or fo r the volume? %SD stands for standard deviation. At each radiation surface/volume a mean value is obtained by averaging the solution of "several accumulators" (multiple calculations for the same quantity). Then, a standard deviation is computed. The maximum standard deviation among all surfaces, or volumes is then reported. Opaque..

 February 8, 2007, 10:17 Re: Monte Carlo - Number of Iterations? #4 opaque Guest   Posts: n/a Dear tsimon, My apologies I did not answer earlier.. you asked: " ..doesn't means that the results are better in the later iterations?" Assuming the temperature distribution has not changed, the MC results should be nearly as good as the previous iterations. Any RMS target used for a radiation calculation (no flow) using MC/DTM only applies to the energy equation. Again, if the k is not zero you need iterations to solve the temperature for the radiation solution to be valid. I assume that your media is absorbing radiation. For a transparent material with all temperature specified boundaries, the radiation solution is obtained in one iteration. Well, distributing the histories (photons) among the boundaries is kind of an art.. ANSYS CFX does not distribute them randomly, but it uses the emission as a weigth.. That is, if one of those 10 surfaces emitts 90% of the total emission in the domain, it will get 90 photons out of 100. Leaving the other boundaries to divide last 10 among themselves (again base on their contribution to the total emission). The main assumption is that boundaries that do not emitt enough energy are not assigned any photons (the minimum is 10 if recall correctly). Basically, the photon distribution is self-adaptive. Hope the information helps, Opaque..

 Thread Tools Display Modes Linear Mode

 Posting Rules You may not post new threads You may not post replies You may not post attachments You may not edit your posts BB code is On Smilies are On [IMG] code is On HTML code is OffTrackbacks are On Pingbacks are On Refbacks are On Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Luiz Eduardo Bittencourt Sampaio (Sampaio) OpenFOAM Mesh Utilities 42 January 8, 2017 13:55 sebastian OpenFOAM Running, Solving & CFD 14 September 21, 2016 10:47 Lord Kelvin OpenFOAM Running, Solving & CFD 8 March 28, 2016 11:08 bookie56 OpenFOAM Installation 8 August 13, 2011 04:03 msrinath80 OpenFOAM Running, Solving & CFD 9 July 22, 2007 02:58