Fluid Simulation Start/End time.

I’ve been trying out the fluid simulator and I have a question regarding
the Start/End time options.

From what’s been written, it’s my understanding that these options allow
one to adjust when the fluid simulation starts and ends, as well as in
conjunction with the Display Buttons Window options the Start/End Frame
controls the overall “duration/speed” of the fluid animation.

In the following images, I’ve set the frame output for 1 to 100; the
Fluid Simulation Start/End time is changed from 0.0 to 0.4, -> 0.2 to 0.6
(maintaining a fluid simulation time of 0.4 seconds).

http://users.xplornet.com/~gimble/Image7.jpg
http://users.xplornet.com/~gimble/Image8.jpg

Something strange seems to be happening at frame 1, 2:
I was assuming that the fluid animation would start at the midpoint of the first animation(with the red fluid) and continue on linearly from there.

However, in the second animation (blue fluid) the level jumps from half way to the arrow at frame 1 to the arrow at frame 2…

Is this the result of a bug with the Fluid Simulator start time option, or am I’m setting something wrong?

Hi Gimble,

that’s basically how it should work - with start time 0.2, blender frame 1 displays a later time in the simulation.

Regards,
-> Nils

Hi n_t.

Yes, but should the final animation jump from frame 1 (frame 50 with start time = 0) to frame 2 (frame 100 with start time = 0)?

From a final animation perspective it would seem strange, assuming a constant inflow rate, that the fluid level should change from 25% to 50% from frame 1 to 2, and then take 98 frames (from frame 2 to frame 100) to increase another 50% to the final fluid level.

Hi Gimble,

ah - I think now I get it, so for the second animation it seems frame1 is t=0.2, frame 2 is t=0.4, and the end time looks more like t=0.8… Yes, that’s probably wrong, I’ll take a look at the code there… Thanks for testing.

Regards,
-> Nils