Skip to content
GitLab
Menu
Projects
Groups
Snippets
Help
Help
Support
Community forum
Keyboard shortcuts
?
Submit feedback
Contribute to GitLab
Sign in
Toggle navigation
Menu
Open sidebar
Arash Partow
waLBerla
Commits
41329b68
Commit
41329b68
authored
Mar 26, 2019
by
Christoph Rettinger
Browse files
Added docu to PdfField class
parent
e0058121
Changes
2
Show whitespace changes
Inline
Side-by-side
README.md
View file @
41329b68
...
...
@@ -9,7 +9,7 @@ in particular the fluid-particle coupling.
It scales from laptops to current and future supercomputers while maintaining
near-perfect efficiency.
See http://walberla.net/ for more information and a showcase of applications.
See http
s
://
www.
walberla.net/ for more information and a showcase of applications.
## Documentation and Tutorials
...
...
src/lbm/field/PdfField.h
View file @
41329b68
...
...
@@ -52,6 +52,21 @@ namespace lbm {
* z-coordinates!
* Also, particle distribution functions (i.e., the values stored in the field) can be accessed using stencil
* directions, e.g. "pdfField( x, y, z, stencil::NE )".
*
* Note that the behavior is different for compressible and incompressible lattice models.
* In the compressible case, the behavior and formulas are as expected from common LBM literature and the density
* is taken as the 0-th order moment of the PDFs and this value is used.
* In order to make LBM quasi-incompressible, it was suggested, e.g. in
* Q. Zou, S. Hou, S. Chen, G.D. Doolen, J. Stat. Phys. 81(1–2), 35 (1995)
* X. He, L.S. Luo, J. Stat. Phys. 88(3–4), 927 (1997)
* that the density is implicitly assumed to have a constant value of 1 in many cases (e.g. in getVelocity()),
* and only the deviation from this value enters some of the formulas, like the equilibrium distribution functions.
* Additionally, the PDFs are normalized around 0 in the incompressible case to increase the numerical accuracy,
* i.e. only the deviation of the PDF values from their respective lattice weight is stored.
* As a result, manually summing of the PDF values will yield the density deviation in this case.
* But the getDensity() function reverts this normalization (by adding 1) and will yield the physical density.
* This normalization, however, usually doesn't affect the implementation of functions like LBM sweeps.
*
*/
//**********************************************************************************************************************
...
...
Write
Preview
Markdown
is supported
0%
Try again
or
attach a new file
.
Attach a file
Cancel
You are about to add
0
people
to the discussion. Proceed with caution.
Finish editing this message first!
Cancel
Please
register
or
sign in
to comment