I need to let the liquid flow along the pipeline, filling.

80229-48e.png

If you just want the visual effect of a liquid flowing along those pipes, you might want to investigate flow maps. The idea is to supply a texture to your shader that encodes a direction vector for each pixel to show the direction that water flows through that point (similar to how a normal map uses a texture to describe the normal direction at any point):

Thank you very much for your help here. I bought the “Liquid Volume” this Shader. Through the help of the author to increase the function of the neglect of gravity. Perfect solution to my problem.