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[Mantaflow] initial velocity ignored in the emission object
Confirmed, NormalPublicBUG

Description

System Information
Operating system: Windows-10-10.0.17134-SP0 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 431.86

Blender Version
Broken: version: 2.82 (sub 6), branch: master, commit date: 2020-01-06 20:54, hash: rB3a35301fd16d
Worked: (optional)

Short description of error
initial velocity ignored in the mantraflow emission object

Exact steps for others to reproduce the error

  • Open file and run simulation.


(In the file the initial velocity is pointed to normal).

Event Timeline

Germano Cavalcante (mano-wii) changed the task status from Needs Triage to Confirmed.Thu, Jan 9, 6:22 PM
Germano Cavalcante (mano-wii) renamed this task from initial velocity ignored in the mantraflow emission object when set to normal to [Mantaflow] initial velocity ignored in the emission object.Fri, Jan 10, 7:22 PM
Germano Cavalcante (mano-wii) updated the task description. (Show Details)
Bastien Montagne (mont29) changed the subtype of this task from "Report" to "Bug".
Peter Boos (PGTART) added a comment.EditedWed, Jan 15, 12:31 AM

This is maybe something that requires some GUI and concept rethinking.
I managed to get an inflow working based upon a plane with a thickness of 1.0
Maybe initial velocities should only be for an inflow plane based, and not be for full meshes with a starting velocity.
I mean it makes more sense that a hoze provides a stream of liquid then a solid shape has certain speed on start.

Here is the file in wich it works for an inflow{F8278636}

I can confirm that a surface thickness of >0.0 circumvents the bug.

Can you post a file showing to us how you did it? I've tried what you said but isn't working for me

Can you post a file showing to us how you did it? I've tried what you said but isn't working for me

Here you go:

It looks like surface thickness is used as a multiplier of velocity for liquids.

It looks like surface thickness is used as a multiplier of velocity for liquids.

I've tried what you wrote. It's not perfectly exact. Actually the surface thickness multiplies the initial velocity only. Infact it doesn't change the gravity force. By the way thank you! You really made it work. Now: Is it wanted? I mean, is the surface thinckness doing this because it is right? According to its description it should control the maximum distance from mesh surface to emit fluid. We will wait for @Sebastián Barschkis (sebbas) to tell us if it's all right.

Actually the surface thickness multiplies the initial velocity only.

Surface thickness multiplies fluid collision probability as well. It's like two different parameters are driven by one slider.
I think T73161 is related to this one.

In a sense they're related they together decide fluid particle density maybe a factor would be easier if we think of fluid inflows as planes. Well this is how I understand it.

@Sebastián Barschkis (sebbas) Please divide those options: "Surface thickness" and influence of the effectors.

Would it not make more sense to just have options to emit from face, edges, vertices (with the ability to select all 3)? And then have an offset option in scene units. The initial velocity shouldn't really be anything to do with where the water is emitting from or how far from the object it starts.

@Michael - (michael) Campbell maybe it's time to think about units sizes and stamdardisation of units it can be a problem in STL experts and measureit add-on normally I keep printing stl standard as mm. The same goes for time in particles mayveas a default use 25fps and 1ms for particles recalculate.values based upon the FPS.

On side note there are also problems with object origin and fluid domain as well