Force field can't expand smoke evenly. #76685

New Issue

Iago Mota · 2020-05-12T16:32:30+02:00

Iago Mota commented

2020-05-12 16:32:30 +02:00

System Information
Operating system: Windows 10
Graphics card: Nvidia GeForce GTX 650 Ti
Processor: Intel® Core™ i7-3770

Blender Version
Broken: (2.83 Beta, 8956e9e5f6, 2020-05-11 19:18 )
Worked: (never)

Short description of error
Blender smoke can't expand in all directions evenly.
The video below shows two situations: one where particles are emitted in an omnidirectional fashion, and one where the "Force" force field is used to push the smoke outwards.
ExpansionDemoC.mp4

Exact steps to reproduce the error
Spherical Expansion (Force).blend

Add a sphere.
Press F3 and select Quick Smoke.
Add a "Force" force field in the center of the sphere.
(optional) Set Buoyancy Density and Heat to zero, to ensure that the only movement the smoke has is the push from the force field.

**System Information** Operating system: Windows 10 Graphics card: Nvidia GeForce GTX 650 Ti Processor: Intel® Core™ i7-3770 **Blender Version** Broken: (2.83 Beta, 8956e9e5f6c0, 2020-05-11 19:18 ) Worked: (never) **Short description of error** Blender smoke can't expand in all directions evenly. The video below shows two situations: one where particles are emitted in an omnidirectional fashion, and one where the "Force" force field is used to push the smoke outwards. [ExpansionDemoC.mp4](https://archive.blender.org/developer/F8530737/ExpansionDemoC.mp4) **Exact steps to reproduce the error** [Spherical Expansion (Force).blend](https://archive.blender.org/developer/F8530793/Spherical_Expansion__Force_.blend) 1. Add a sphere. 2. Press F3 and select Quick Smoke. 3. Add a "Force" force field in the center of the sphere. 4. (optional) Set Buoyancy Density and Heat to zero, to ensure that the only movement the smoke has is the push from the force field.

Iago Mota commented

2020-05-12 16:32:30 +02:00

Added subscriber: @Iago-Diogo-de-Vasconcelos-Mota

Iago Mota commented

2020-05-12 16:34:02 +02:00

An unqualified guess here, so please correct me if I'm wrong! But I suppose this might be due to Blender treating this as if no more pressure is being added to the smoke. So, despite the insistence of even velocity, the smoke can't expand properly. However, due to the constant emission of new particles or the fact that Flow Behavior is set to Inflow, I believe it follows that more pressure should be added over time.

Eitan Traurig commented

2020-05-12 17:21:24 +02:00

Added subscriber: @sebbas

Ankit Meel commented

2020-05-13 17:17:13 +02:00

Added subscriber: @ankitm

Ankit Meel commented

2020-05-13 17:17:13 +02:00

#74060 (Smoke flow force field not working with Mantaflow Gas)

Richard Antalik commented

2020-05-14 21:27:47 +02:00

Added subscriber: @iss

Richard Antalik commented

2020-05-14 21:27:47 +02:00

I have created new report for particle system - #76765 (Particle System as flow source doesn't work)

Will have a look at force field problem.

I have created new report for particle system - #76765 (Particle System as flow source doesn't work) Will have a look at force field problem.

Richard Antalik changed title from ~~Smoke can't expand evenly.~~ to Force field can't expand smoke evenly.

2020-05-14 21:37:37 +02:00

Richard Antalik commented

2020-05-14 21:55:04 +02:00

Changed status from 'Needs Triage' to: 'Needs Developer To Reproduce'

Richard Antalik commented

2020-05-14 21:55:04 +02:00

It is quite evident that to get nicer results, you need higher domain resolution.

But even with higher resolution (128) there is quite non-uniform pattern created. This may be technical limitation though.

It is quite evident that to get nicer results, you need higher domain resolution. But even with higher resolution (128) there is quite non-uniform pattern created. This may be technical limitation though. ![untitled.jpg](https://archive.blender.org/developer/F8536027/untitled.jpg)

Iago Mota commented

2020-07-15 20:40:35 +02:00

Sorry for no updates here in the past months! I haven't ever been able to get this kind of expansion to be regular before or after Mantaflow was released, so I don't think this is particularly a Mantaflow bug. Also, I tried this in 2.90.0 and it looks like some smoke is moving into the emitter, despite the Force force-field trying to push it out.
C-Irregular expansion.mp4
Smoke Expansion -Force-.blend

@iss By the way, I'm not sure if the particle simulation issue in this report is related to #76765 , as this issue was also present in 2.81 and 2.83.0 where using a particle system as a flow source still worked. The problem here is that the smoke doesn't continue in an even, spherical movement, even if the initial velocity of the particles is forcing it. I might be misinterpreting, so please correct me if I'm wrong.

Sorry for no updates here in the past months! I haven't ever been able to get this kind of expansion to be regular before or after Mantaflow was released, so I don't think this is particularly a Mantaflow bug. Also, I tried this in 2.90.0 and it looks like some smoke is moving into the emitter, despite the Force force-field trying to push it out. [C-Irregular expansion.mp4](https://archive.blender.org/developer/F8697631/C-Irregular_expansion.mp4) [Smoke Expansion -Force-.blend](https://archive.blender.org/developer/F8697656/Smoke_Expansion_-Force-.blend) @iss By the way, I'm not sure if the particle simulation issue in this report is related to #76765 , as this issue was also present in 2.81 and 2.83.0 where using a particle system as a flow source still worked. The problem here is that the smoke doesn't continue in an even, spherical movement, even if the initial velocity of the particles is forcing it. I might be misinterpreting, so please correct me if I'm wrong.

Richard Antalik commented

2020-07-15 22:42:46 +02:00

#76765 us technically unrelated. There were 2 bugs mixed in one report

Philipp Oeser removed the

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Force field can't expand smoke evenly. #76685