Upres Factor

– As you know baking a simulation at different resolutions leads different behaviors.

– Upres Factor let you to ‘rise up’ the resolution of a simulation without changing its overall behavior.

– You can find Upres Factor in the Tab ‘Noise’ as this parameter is used when you want to add noise to your smoke-fire simulations.

– The bigger the Upres Factor the bigger the ‘added resolution’ :

Blender Smoke Upres Factor

Temperature Maximum and Minimum

– The Minimum Temperature Ignition is the lowest temperature at which a combustible substance (when heated) takes fire in air and continues to burn (Temperature of Ignition).
– Maximum temperature is the highest temperature a flame can reach (for a given combustible).
– If you know these two parameters for a specific substance Blender let you set them in this tab.
– The values are expressed in Kelvin/1000
– Converting Celsius (°C) TO Kelvin (K) is easy: T(K) = T(°C) + 273,15

– In this example I rendered the flames produced by two different substances: Butane (Temperature Ignition: 678,15K ; Maximum temperature: 2243K) and Oxyhydrogen (Temperature Ignition: 843,15K ; Maximum temperature: 3073,15K)
– You have to divide all values by 1000 so that the value you have to insert are:
– Butane: Temperature Ignition: 0.67815 ; Maximum: 2,243
– Oxyhydrogen: Temperature Ignition: 0.84315 ; Maximum: 3,07315

– Remember: in these videos I only want to explain what these parameters mean, these simulations does not pretend to be ‘realistic’. First of all I usually set a reduced Time Scale so that you can appreciate better the evolution of the system, and second I focalize on a specific parameter while a good simulation needs to adjust lot of parameters, materials, lights etc…

– First example, Butane and Oxyhydrogen:

– Does these two parameters make sense if you are rendering a flame without using specific values for specific substances? Blender let you use, and not only in fire simulation, values that lead to not realistic phisical simulations, and I think this makes Blender incredible as it let your fantasy unwind and create!

– Second example changing only the Temperature Minimum (Temperature of Ignition):

– Third example changing only the Temperature Maximum:

Blender Smoke Flames Temperature Maximum Minimum Ignition

Initial Velocity – Normal

– When using a mesh source, this option controls how much velocity smoke is given along the source’s normal.

Initial Velocity – Source

– Multiplier for inherited velocity. A value of 1 will emit smoke moving at the same speed as the source.
– Note: this is only the INITIAL VELOCITY! After the emission both smoke and fire follow their usual behavior.

– In this video the effect for Source = -2.0 is more evident during the ascending motion (the resultant Initial Velocity vector is opposite to the ascending flow).

– Another example: I set Temperature Difference = 0 so that the smoke does not move away from its poit of origin unless it has some velocity.
– During the firsts 50 frames the flow emitter doesn’t move, all fire and smoke emitted don’t move from their origin.
– For Initial Velocity = 0 you obtain a very weird effect, of course as both smoke and fire are emitted with no velocity, they don’t move from their points of emission.

Blender Smoke Initial Velocity Source

Mesh – Volume

– Amount of smoke to emit inside the emitter mesh.

– 0 = 0% , 1 = 100%

– Attention: may have unpredictable results if your mesh is non-manifold.

– It isn’t so easy to show the smoke inside an objec, so I tried to make a two videos showing a sphere with 0% and 100% of smoke inside viewed from above. You will also notice a pattern generated by the voxels.

– You can see (expecially at the very beginning of the video) much more smoke near the borders of the sphere in the case of Volume = 0 and a more uniform distribution in the case of Volume = 100%.

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– The same videos from another point of view:

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