[Nek5000-users] Visualizing lambda2 vortices

[nek5000-users at lists.mcs.anl.gov]

Those are lambda2s, with pressure mapped onto the isosurface.

Here is another - www.mcs.anl.gov/~fischer/hemi/hemi_0700.gif

These are isosurfaces of lambda2 (probably lambda2 = -.1 or something
--- usually a slight negative bias is required).

In VisIt, you can select an isosurface of scalar A and then map
scalar value B onto that surface as a pseudocolor plot.

The plate and hemisphere are visualized by setting A to
be velocity magnitude=.0001 (say) with B=pressure.

The lambda2 vortices are visualized by setting A to be temperature
(which is where lambda2 is stored in my case) and B to be velocity
magnitude.

(Choosing B to be pressure for both the walls and the vortices
did not yield high contrast...)

Paul



On Wed, 29 Sep 2010, nek5000-users at lists.mcs.anl.gov wrote:

> Hi,
>
> I was looking at Paul's pretty picture (
> http://www.mcs.anl.gov/~fischer/cfd/hairpin_split.html) which I assume is
> iso-surfaces of vorticity and had a question regarding visualizing lambda2
> vortices. I have the lambda2 vortices calculated and stored as a passive
> scalar in the field files but cant figure out a way to visualize them. How
> do you generally visualize the dominant structures in the flow, say for eg,
> the hairpin vortices in the same animation ?
>
> Regards
> Shriram
>