Force analysis for fluid micro-element in tubing.
|S/N||Name and Symbol||Expression||Orientation|
|1||Total pressure of fluid on Section S1–S1, FS1||γS(H − z)||Pointing to the direction of the downstream and along the pipeline axis|
|2||Total pressure of fluid on Section S2–S2, FS2||In contrast to FS1|
|3||Component force of weight control along tubing axis Gl||Same as FS1|
|4||Elastic force of casing wall caused by the expanding of cross section Fe||Same as FS1|
|5||Friction of casing wall f||πDdlσ||In contrast to FS1|