Solid inside moving fluid

Hello, I have completed most tutorials provided on this website, and I have three questions;

I want to calculate the total force put on the solid inside a fluid flow, and the first question is should I create a box first and assign inlet outlet conditions to model the fluid flow, or should I just assign material in 'sim' and choose initial velocity condition?

The second question is, in the 'incompressible flow through a pipe into a box' tutorial, you have chosen the face between the inlet and outlet face as the seed source for the particles, but on the next picture, the particles start from the inlet face. Then what is the role of choosing the face as the seed source? can I just choose the inlet face as the seed source?

The third question is, after I drafted the shape of the solid I want to put inside the moving fluid (I did assign wall condition for every face) and I used 'show particles'to see the fluid flow. However, the particles did not bend around the solid surface. Do I have to assign other conditions to make the fluid flow around the solid?

Thank you.

Require watertight flow volume

In every RANS Flow tutorial there is a detailed description of applying Substances to volumes and boundary conditions to faces, please review this process to address your first question. Each boundary face requires a boundary condition.

You have to create a single watertight flow volume. In your case you need to subtract your internal solid from the external solid. If you have symmetry in your model then you can mimic the approach in the tutorial "Wheel in a Box."

Particles/streamlines are calculated upstream and downstream by default from the seed source, that's why they appear to originate from the inlet in the tutorial. You can use any geometry entity as a source, including an inlet face.