i tried to implement a D2Q25 model basically for performance comparision purposes.

but i failed to look up the weighting factors for such a model.

I also couldn’t find a formula to calculate these factors.

can anyone help me with this problem?

I vaguely remember having read about a D2Q25 lattice in the Wolf-Gladrow book. What are you actually implementing? BGK?

There’s just the referenz to Kronreich and Scalo “Supersonic lattice gases…”, Physica D, 69(3/4) 333-344, 1993 who proposed 2d models with 25, 57 and 129 links. You can read the paragraph in the Wolf-Gladrow book here: http://books.google.de/books?id=cHcpWgxAUu8C&pg=PA134&lpg=PA134&dq=Kornreich+Scalo+1993&source=web&ots=I7j9JmuWAh&sig=cA4JPPx9oB-DFjLuUu4UHyeUDgo&hl=de

I’ve read this article. They don’t write anything about the weights they used, they even don’t mention it as far as I remember. :S

I’ve tried to compute them with the help of a paper of Watari (2007, I don’t remember the exact title but it begins like “Possibility of constructing multispeed LBM …”), but I found a singular system of equations … Too bad, but I will check it.

There is a new paper by Iliya V. Karlin “Lattices for the lattice Boltzmann method”

I test it. you can work with a lower tau.

Also It will give you a good results specially when using open boundary condition.

"Accuracy analysis of high-order lattice

Boltzmann models for rarefied gas flows"

(2009, Jianping Meng and Yonghao Zhang

thanks