It seems to me like you have mixed up the automatic Mesh Creation (Simulation Object Container - Fluid Domain) with some Boundary Condition which in this case aren't necessary (i.e. Flow Surface).
As we only have few information about your simulation please reply if it is not the case.
Also, this is my question.
I am doing flow simulation in NX thermal/flow. I have a throttle valve inside a tube. The angle changes from 0 to 90 in steps of 10.. Is it correct to give it in flow surface as rotational parameters. It asks for the option of motion type and rotating rate.
sorry for the late reply. As far as I know, you have 2 options when it comes to meshing the fluid with NX:
1. Using the Fluid Mesher. Creates the mesh automatically and has limited setup options. You can just add a boundary layer. If you use this method, you don't need to define the boundary layer. If you do so, you'll get the error.
2. Create your mesh manually. Activating your mesh below the Model Display inside the Simulation Navigator, you get access to more advanced meshing options (2D, 3D, Hexa8, Tet4, Elementsize on edges, etc.). If you use this method, you will need to define your boundary layers. If not, NX will use the Slip-Wall conditions on them. It is also important making sure to use the proper Boundary Flow Surface option. It may happen to be set to Embedded Flow Surface which also may cause errors.
I'm also quite new to NX so if anybody notices erroneous information please correct.
Good luck and best regards
My approach for your problem would be setting up a Parametric Study. In your Assembly I would try to give the Ange of the Throttle a specific variable name. With a Table you could then specify the angle values needed. Then you have to find out how to run the Parametric Study.
I'm sorry for not be able to give you a step by step tutorial. As I've already said, I'm also new to NX Flow. I just know how I would set it up with other CFX-Software.