[Paraview] Oilflow - Surface flow

[lovecraft22]

Thank you Richard.

The LIC seems heavy when you pan, zoom in or zoom out your geometry, not in generating the flow paths. What you get is actually really nice.

If there no way in getting good streamlines (as you pointed out I got short lines only) then the LIC is fine.

Maybe there's a way of generating that directly in openfoam, as there is for free flow streamlines.

Thank you again for your time.

Lorenzo

Il giorno 29/mar/2012, alle ore 15:58, Richard GRENON <richard.grenon at onera.fr> ha scritto:

> Hi Lorenzo.
> 
> The Stream Tracer works very well to follow a 3D streamline in a  volume, but I always got bad results to follow streamlines on a curved surface. When you start from a point on a surface to follow a streamline, the next point is found with a small step in the direction of the tangent vector, but this new point is not on the surface if the surface is curved. So the new point should be projected onto the surface before proceeding to the next step. It seems that  the Streal Tracer algorithm does not project correctly the new point at each step, so you get only small pieces of streamlines, depending on the curvature of the surface. The more the surface is curved, the more the Stream Tracer has difficulties to remain on the surface when following the stream line. The Stream Tracer gives good results on a surface only if the surface is plane.
> 
> For me, the LIC plugin was a marvelous workaround for surface streamlines, and for two reasons. First, it gives quickly pretty pictures. Second, it gives at a glance the whole surface flow pattern, so you can easily identify complex separated flow regions without having to guess seed points as you would do with the the Stream Tracer. Now I am always using the Stream Tracer for 3D streamlines in a volume and the LIC plugin for surface flow patterns.
> 
> I don't understand why you say that LIC is "heavy" in Paraview ? Once you have a surface vector in your data, you have only to change the Representation from Surface to SurfaceLIC and the rendering is immediate, and I think faster than computing streamlines. The only drawback of LIC is that it depends on your graphic card, and it may not work depending on the version of your driver.
> 
> Richard.
> 
> 
> Lorenzo a écrit :
>> Hi all;
>> I managed to calculate the wall shear stress in openFoam using the command
>> wallShearStress -latestTime
>> and using the results (vector) as in input for the LIC!
>> 
>> That's great!
>> 
>> Now I'd have another question related to this topic:
>> as I see the LIC is pretty heavy in paraview even though mine is a small geometry. I'm wondering, once I've loaded the wall shear stress, I could use the stream tracer on it to get more or less what I want. The only problem I'm having is that the line that generates the streamlines needs to be exactly on the surface of my body. Is there any way to attach the line to the surface?
>> 
>> Thank you again!
>> 
>>  
> -- 
> Richard GRENON
> ONERA
> Departement d'Aerodynamique Appliquee - DAAP/ACI
> 8 rue des Vertugadins
> 92190 MEUDON - FRANCE
> phone : +33 1 46 73 42 17
> fax   : +33 1 46 73 41 46
> mailto:Richard.Grenon at onera.fr
> http://www.onera.fr
>