you can merge velocity components into one array using Merge Vector Components.
you can try the Streamlines filter, that creates streamlines (from some generated seeds)
Thanks @nicolas.vuaille Sir for your quick response.
Firstly, I am trying to generate the 3d domain (attached fig) with CSV data, where a circular cylinder is placed at the center.
Mainly to avoid the 3d triangulation to the inner cylinder and then other result plots (streamlines mainly).
Creating meshes (including surfaces) from point cloud is not so easy task.
I fear you need Delaunay. Then you may Extract surface if you do not want inner triangles, and you can Clip with a cylinder to remove the inner cylinder.
Also, if you have more issues with this part, a new post may be more appropriate: I’m not expert on meshing and people who does will not be catched by this post