# Some newbie questions.

Hello,

I just downloaded the Caedium trial version, and I have some simple questions,
(I hope someone can help out..) I made a model that works quite well, but I have some difficulties;

- I want to show the particle trails in 3D, how do I do this???.
(I can show the 2D trails, but what should I do to activate the 3D trials?)

- I saw some movie's showing time related trials, is it diffcult to make these movies???.
(I pushed the record button, but I suppose there is more to be done to make this)

Further;

- The simulation I made is an enclosed flow, Is it also possible to make an open flow?.
(like it happens when a ship sails through open water, one face it open to air)

- Is it possible to different kind of flows in one model?.

I hope somebody can give me some hints, much thanks in advance.

Fhoos

### Streamlines...

Hallo,

Thanks for this quick reply; I will continue with these tutorials.

To be more specific, with an open flow I indeed mean a water to air surface;
If we simulate this as an enclosed water flow, will this be in someway representative to an open water flow? (does anyone know this from out of the theory).

Can we also calculate the reaction forces, of an object in a current?.
(like for the object/volume in total)

And sorry one last question; by mistake i once was able to show specific 3d streamlines.
(not all but just a selection of some) can this be controlled in a specific way?.

Regards, and thanks in advance, fhoos

### Not ideal but you could try separate simulations for each phase

I suppose if you impose the water-air free surface and model just the water portion then you might be able to get the right order of magnitude for the forces. Then you can perform the same style of simulation for just the air portion if you think it's significant.

Yes, Caedium can calculate forces on a body, the wheel tutorial shows how.

Sometimes the initial values for the streamlines aren't ideal, so often reducing the Increment property helps. For details see the tip for particles and streamlines I mentioned previously.

### Streamlines and Animation

For detailed instructions on creating streamlines (I presume this is what you mean by 'trails') see the tutorial "Incompressible Flow Through a Pipe into a Box". For more details on particles and streamlines (including animation) see the tip "Particles or Streamlines".

For detailed instructions on an external flow see the tutorial "Flow Over a Rotating Wheel with Moving Ground".

I presume by 'different kind of flows' you mean water and air? If so then no, Caedium does not currently support multi-phase (free surface) simulations.