I am trying to extract the lower half of a circle using the constructdomain2 command.

The context of this is that I am modelling a stream in a topographic model. The stream bed has been modelled as a negative of a pipe-variable (topographic model with pipe subtracted from it). I am now looking to ‘fill’ this with water which is to be modelled by the same pipe, but with the waterline just below the edges of the stream (using Isotrim command to remove the top half of the pipe).

It says that a domain of 0 - 0.5 will extract the bottom half of the circle. I would like a subsurface of approx 0 - 0.4 (so that the water line sits below the edges of the stream). Inputting these numbers as a domain works except that I can’t control where on the circular section of the pipe this domain starts.

How do I control where the domain starts on the circle?

Thank you for replying. The trimmed surface you have produced is ideal, except that I would like the inverse of it, so the bottom half, I would then like to patch the rails to create a solid shape that mimics water in the stream.

Can you show how I could retrieve the same shape, but the bottom section, as per image 3 of my original post?

Thanks again. See, the axis that runs across the circle from 0.5-1.0 is on somewhat of an angle, compared to yours. Do you think this is to do with the long, varied pipe-variable geometry mine is based on?

Hi Seghierkhaled, I’ve seen your reply of this thread which so close to my key point, but I still can’t get through this problem, would you mind give me a hand ?