About 2.90 Comparison:- In the Tweet, Sebastian Tweeted that, 2.90 will have some Changes to Gravity. I Tried Changing The Scene Gravity, to a point where the smoke will match the height of what 2.82 and 2.83 had when they were at frame 61

When I changed to 16m/s², It Kinda looked similar to 2.83! But Still wasn't The Height of 2.83 at frame 61. But the Shape Was Similar to 2.83 as You can SEE:-

Blender Version:- 2.90.0 Alpha, branch: master, commit date: 2020-07-17 07:39, hash: 0a40c671b0b5, type: Release

Note:- This was a Separate test. I did not import anything, I created Cube and Domain of same size as in the prev files and same quick smoke with same changes as described at the Task Description. I am pretty Sure that Importing would have not solved it. as described on T78290

Yes, I looked into this and it turns out that there are 2 things that make the smoke look different (2.82 compared to current master 2.90):

• Smoke more Dense: Is due to the changes from D6951. From 2.83 on smoke looks more dense in workbench - if you render in Cycles, for example, the result should be identical though.
• Less Gravity: In general, the gravity should be more physically-correct for fluids in 2.90. With the current buoyancy settings smoke will rise less quickly (when compared to 2.82).

@REYNEP (NWERO) can you try out the following things:

• Bake and render a simulation in 2.82, open it in 2.90 and render. The rendered results should be the same.
• In 2.90 and with the file from 2.82, change both buoyancy parameters ("Buoyancy Density", "Buoyancy Heat") a bit (e.g. increase them from "1.0" and "1.0" to "4.0" and "5.0"). Then simulate. Then open those results in 2.82 and compare them to the original 2.82 simulation (with buoyancy "1.0" and "1.0"). The simulations should look very similar in workbench.

In the future and if people prefer faster rising smoke, it might make sense to increase the default buoyancy values a bit.

My APOLOGY For Late Reply, @Sebastián Barschkis (sebbas) Sir. I checked Out, (With The Same 2.82 Version and 2.90 Version) I tried Baking, and rendering in 2.82 and then opening and rendering it in 2.90. They Look Similar Just As You Said, Both in Workbench and After Rendering!!😄, (I Think I am Gonna Share Some Tests with Force Fields with 128+RES!) What I wanna Demonstrate here inside the VIDEO is that. 2.83 96RES Looks really different from other 96RES Sims. Other 96Res (Including 2.90) Sims are Really Different From 128Res, except for 2.83 96Res (2.83 96Res is Identicle to 2.83 128Res)!

Here Goes First 100 Frames (SAME Quick SmokeSETTINGS and same Quick-Smoke Default Shader only with Density 7) :-

(BTW, LATE BCZ I have been doing lots of Test Sims 😃) Last Update: Out of 10 Videos, I made 1, Where I have Put all those Side by Side in their Original 720p Video Resolution - Which Makes this Video (2560*1440 px)

This is a Comparison of Same 2.90 QuickSmoke Settings (with Buoyancy Density=4.0 and Heat=5.0) in Different Resolutions

Ok, nice comparison, thx! I can see that with increasing resolution the smoke seems to rise slower. That's definitely an issue that needs to be addressed (i.e. fix scaling of buoyancy parameters).

The rightmost example in the above video (res 96) seems a bit out of place though. Are you sure it was simulated correctly?

Are you sure it was simulated correctly?

Yes, I did This Multiple Times, Because at First I was confused too. I was Questioning myself Too, Seeing the Changes Yesterday Night, Then i tested Again Just an Hour ago....

Can you quickly check if your simulation gives you a similar result with res 96? I just made this with the daily build (731d9f0bfa40 ) and the 2.83 test file from this report. I think from the shape it looks more similar to the results you had with res 98 and res 100.

On it, @Sebastián Barschkis (sebbas) Sir....

Adding Video, Yes Sir With The Build that you Have Specified, It Works, Just as expected....
Blender version: 2.90.0 Alpha, branch: master, commit date: 2020-07-20 20:08, hash: 731d9f0bfa40, type: Release

But the Build I used from 4 Days Ago (Daily Build:- 0a40c671b0b5), Does Not Work (Update:- I think This File's Liquid Object Size is Smaller):-

(Update:- 2nd Video's (16JulyUpdate) Liquid Object Size is Smaller)

And 1 More Thing @Sebastián Barschkis (sebbas), Sir. Here is a 2.83.2 Comparison of RES 64, 96, 98, 100, 128, 256:-

Also I don't think 2.83 is 100% Accurate, Because when I increased to 256, You can See "That GasFluid That Comes Out of the Center", Happens Too early Compared to 128Res or 96Res I Am Gonna check This in 2.90 Now.

I Think I have Got Why The 20July Build was Doing Great @Sebastián Barschkis (sebbas) .... And I Think It Was Fixed because of the Size of the Liquid Object

It is a 3 Minute Long Video, But I Think It Will be Worth it....

1. Note:- The File That I used for 2.83, The Size of the Liquid Object was same as The Liquid Object I used for 2.90....
2. First I opened the File That I used for 2-90 Buoyancy Dens=4,Heat=5, Res=128
3. Changed the Res to 96, Baked with 2-90 20July Update, This bake was WRONG
4. Then I Increased Scale of the Liquid Object a lil bit, Baked with 96 Res, This bake was Good
5. Then I tried Manually Changing the Scale Value of Liquid object 0.151, 0.152 Did not work, but 0.158 Worked! It Looked similar to 128 Res
6. But that same Scale value of 0.151 Looked OKAY with 128Res
7. UPDATE:- I Opened the 2.90 Buoyancy File in 2.83.2 and changed the Buoyancy Values to 1.0, Then baked with 96Res, It Looked more Like (but not FULLY same) Original 2-83 96Res Bake

Sir @Sebastián Barschkis (sebbas), Are you There? I think latest 2.90 Still has that Problem when the Liquid Object is Smaller than a particular Size

@Richard Antalik (ISS) Sir, I think There was a Misunderstanding about the problem.... I Explained it In the Last COMMENT With VIDEO.

In any case once developer confirms the report, don't change status yourself, otherwise it can disappear from workboard and can be forgotten.

Copy that, Sir.... (I misunderstood what "Confirmed" Meant, My Bad 😓)

In T79029#982955, @Sebastián Barschkis (sebbas) wrote:

Interesting, not sure which commit made that change. Anyways, to summarize the bug for now:
The shape of the smoke plume should not differ when changing the resolution (which it does as of now, 731d9f0bfa40)

I can confirm that in the 2.83 file provided in the initial post.

Just a Reminder, what was happening was Happening because of changing The size of Flow object by a really small amount, I tried to Explain that in my last comment, the Video is quite Long, but only the first 1 minute explains it too

Mantaflow (fluid simulator) has no active developer at the moment. Moving those bugs as known issues so at least other users can find their issues already reported.