How to 'fill' a sphere
 

Hi,
I'm having problem to fill a sphere with the fluid in geometry. Can somebody teach me how to do it? The sphere is attached to a pipe. I've done fill the inside of the pipe as 'fluid' but I don't know how to fill the inside of the sphere with 'fluid'. Thanks in advance.

Are you preparing this for CFD of the innermost region? Then you would need to do a boolean with a larger volume (perhaps a cylinder primitive), using the objects in the photo as the cutting objects.

yes, i want the sphere to be filled with fluid. But I cant make it. Please advise.

I assume that the sphere is a closed volume and did not have a large hole in as the picture shows. if you delete the surface between the sphere and the tube then you can make the fluid region as a one volume.
Alternatively, if you can use ICEM (I don't know how to use ansys mesher) you can make two fluid regions and assign the connected surface as an internal wall (tetra mesh setup).

If the sphere has a hole in it, you can make a surface to close the surface and make fluid region there. later you can add the boundary conditions of inlet/opening/outlet or whatever you desired with that added surface.