"Chris Huff" wrote:
> "Rune" wrote:
> > I have never understood what use the temperature feature is.
> > What can it be used to simulate?
>
> Mainly convection and the effects of smoke rising and cooling.

Aha.

> > From the documentation:
> > > As the simulation goes on, particles will tend toward the
> > > temperature of their environment. Particles hotter than
> > > their environment will tend to go against gravity and float,
> > > colder particles will sink.
> >
> > I don't see the logic in this. It has noting to do with reality. Hot
> > water doesn't float just because it's hotter than the air around it.
>
> Huh? Water normally doesn't float in air...

When water is below 100 degrees Celsius / 212 degrees Fahrenheit it falls.
When it is above, it rises. The "threshold" is at 100 degrees Celsius, not
at the temperature of the environment. So the "rule" does not apply to
water, not always anyway.

> The reason convection happens is the density difference between
> one mass of air, and the surrounding air. The density is affected
> by the temperature, which will cause a warmer mass of air to rise.

But the particles themselves are not air, right? They just drift around with
the air surrounding them. So if smoke is surrounded by hot air, it will
drift upwards along with the air. However, all this only applies to
materials that have densities very close to the density of air (like smoke).
It doesn't apply to many other materials such as cool water which does not
normally drift along with air, even if its temperature is higher than the
environment temperature.

Since the temperature feature does not apply to all uses of the system, can
it be turned off?

Rune
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