welcome to this quick start tutorial for
Phoenix fd4 3ds Max in this video we
look at creating a gasoline explosion
simulation using a fast preset and then
rebuild it manually to understand it
more fully take a look at the tap water
simulation in our previous quick start
video for a little background on the
concepts that we continue here now we'll
start in a blank scene and I'll create a
sphere that will be the emitter from my
simulation and I'll set its radius to 24
m in the customize menu choose units
setup you should be in metric units
using meters and confirm that the system
unit setup is set to 1 unit equals 100
cm or 1 M this is to ensure that the
simulation will be quite large for a
massive explosion and as we saw with the
tap water Sim in our previous quick
start video scale is important to an
accurate Sim
with the sphere selected click and hold
on the explosion preset icon in the
Phoenix FD toolbar and choose this
second icon for the gasoline explosion
preset this creates the simulation
container with the sphere as the source
now select the start simulation
icon I'll elapse several minutes here to
see the Sim progress into this fiery
explosion and I'll stop the simulation
with the toolbar icon
as I move around the scene we have a
nicely detailed explosion which should
hopefully warn you against playing with
matches and
gasoline so we did this pretty easy
using a preset but now let's take a look
at setting this up manually to get a
deeper look at the workflow click the
trash icon in the toolbar to delete the
cache from the scene select the
simulator and delete it also select the
source node and delete that leaving just
the sphere in the Phoenix tool bar click
on the create a fire smoke simulator
icon and click and drag to create a
volume shown here in the pink colored
lines I'll place the sphere a little
more centered at the bottom of the
container select the simulator and in
the modify panel open the grid roll out
and notice that our Sim is at about 230x
220x 123 M which is good for what we're
looking to do its resolution the total
cells value is at about 6.1 million
I'll decrease that to speed up the
simulation by clicking the decrease
resolution button here three times to
get it down to about 825,000 for total
Sals for more information on this please
see our previous tap water quick start
video and now we just need a source
click the create fire smoke Source icon
in the toolbar and place it in the scene
like so in the modify panel click the
add button and then select the sphere to
add it as an emitter for the explosion
The Source node is where we control a
lot of the simulation settings so in its
modify panel turn off the temperature
and smoke options and turn on fuel the
outgoing velocity parameter controls the
speed of the discharged fluid so
increasing this value will discharge
more fluid into the Sim per second since
we're creating an explosion we'll need
to discharge a large amount of fluid
over a short amount of time make sure
you're at frame zero and turn on auto
key and set outgoing velocity to 2,000
go to the next frame and set outgoing
velocity to zero and 3ds Max sets a key
turn off auto key select the simulator
and start the simulation but nothing
really happens in the modify panel go to
the fuel roll out and turn on enable
burning which is generally what happens
when I eat spicy
tacos click the start simulation icon
and you'll notice that still nothing is
happening stop the Sim again and expand
the fuel settings the ignition
temperature is the temperature at which
our fuel ignites and burns Phoenix FD
uses 300 Kelvin as the default ambient
temperature in a Sim so if you set a
value slightly below 300 such as 290 and
then start the Sim you get ignition
inside the container now the explosion
is looking a little bit bit like a cream
puff right now the preview quality is a
bit ratty expand the preview roll out
and scroll down to the bottom and turn
on the enable in viewport option in the
GPU preview section now the blast is
clipping the edges of the simulator go
back up to the grid roll out and change
adaptive grid to temperature now this
will expand the grid depending on the
temperature of the fluid inside when it
meets the specified threshold set this
threshold to
600 let's get the explosion not to clip
at the bottom where the ground is set
your boundary conditions to a z axis of
jammed negative this allows the
explosion to react to the bottom of the
Sim in other words the ground start the
Sim again and I'll elapse about 20
seconds here to see the Sim reacting
nicely to the ground stop the Sim and
take a look the explosion looks way too
uniform right now select the fire Source
object and in the modify panel introduce
noise to the Sim's discharging fluid by
setting the noise parameter to 10 play
The Sim and the explosion shape is
looking more broken up as this continues
to sim let's focus on the render
settings select the simulator expand the
rendering roll out and select the
volumetric options
button expand the fire roll out notice
there are three opt options for the fire
opacity mode that will control part of
the look choose uone opacity and the
viewport updates stop the
simulation the graph here controls just
the opacity of the fire click to add a
new point to the curve and drag it up
and down to affect the opacity of the
fire lower opacity reveals more of the
internal fire content making it look
brighter and increasing the opacity
hides more of that internal structure
click the expand button for a larger
view of the graph Now set a few new
points and create a look like this wave
I'm making to create more visual
interest to the explosion we can tweak
the opacity with the opacity multiplier
value I'll set that to 0.5 and the Fire
gets brighter but if you back down on
the physically based value like to
0.75 the Fire gets a good deal more red
and orange added to it this par ter
balances between how much of the fire
intensity comes from the color gradient
plus the fire multiplier versus how much
is calculated using the physically based
black body Shader you can change the
color of that fire by sliding this arrow
and when you doubleclick it you can
select a color like this green and blue
that I'll pick to make a point I'll
cancel that action and we're back to the
red from before I'll scrap the timeline
to see how the simulation is doing it
looks a bit too contain still so expand
the Dynamics roll out under conservation
increasing the quality parameter allows
the Sim to spread out a bit more and
swirl better set the value to 80 and
restart the simulation the higher the
quality value the more simulation time
is needed so be careful when going too
high as I elapse about 40 seconds of
time here you can see that the Sim is
breaking up a bit more but it's just not
quite there yet click open the
volumetric op options in the rendering
roll out again disable the fire for now
there's a lot of smoke in the result as
the fuel is burning up stop the Sim to
address this
easier in the fuel settings reduce the
smoke amount to 0.4 to allow for more
burning for a brighter fire and increase
the smoke threshold to one which will
lessen how much of the fuel is created
as
smoke lastly lower the propagation value
to two to reduce how fast it propagates
throughout the Sim set the fires based
on parameter back to temperature and
play The Sim and we're getting better
results but it's just looking too hot
right now so I'll stop The Sim and
reduce the energy to five and then play
the Sim again I'll elapse about 30
seconds here and our Sim looks pretty
neat but the blast stays too hot for too
long what I want to do is cool off the
explosion faster go ahead and stop the
Sim expand the Dynamics roll out and
increase the cooling value to 0.3 and
we'll get the fire to cool faster inside
the simulation play The Sim and over
about 30 seconds of a lapse time you can
see a much more interesting result but
our smoke looks too thin right now
expand the smoke opacity roll out and
set the simple smoke opacity value to
0.9 to give us thicker smoke as the Sim
continues
expand the smoke color roll out and set
a darker gray to get deeper darker smoke
reduce the external scatter multiplier
to 0.8 so that the light inside the
smoke scatters less and you should
notice a slight darkening of The Smoke
Stop the simulation and scrub the
timeline to evaluate how it
looks the fire looks weaker now so
expand the fire roll out in the volume
render settings and increase the fire
multiplier to five to get you hotter
fire inside the explosion now make sure
vray is set to be your renderer in
render setup and let's go ahead and
render the
result now we need a ground plane so in
the create menu select vray vray plane
and click to create one in the scene set
it just a little bit lower and give it a
gray
color click r again and we have a ground
that is actually lit by the
explosion but it's a little bit too
bright in the volumetric render settings
under the fire roll out set the light
power on scene value to
0.5 and render the frame and you've
reduced the lighting cast into the
scene we need a higher resolution for a
better result so in the modify panel go
to the grid roll out and click increase
resolution 3 times to have about 6.1
million total cells again and rerun the
Sim now I'll elapse about 6 minutes of
sim time as we watch this explosion
resolve with a higher quality and there
we have it now let's take a look at
using this in a practical scenario open
the file barrels Max start. Max and
you'll see three metal barrels in the
scene and a camera called camera 1
select the first barrel and select the
gasoline explosion preset in the toolbar
change your cell size to
03 M for a faster simulation speed start
the Sim and our Barrel explodes so let's
get the other barrels to explode as well
stop the Sim and take a look in the
perspective camera select the source and
shift drag to copy the source and move
it over like this in the modify panel
click add and select this second Barrel
to attach it to the Second Source make
sure that the barrels are inside the
simulation container so I'll move mine
over a little bit like that now if I
start the Sim both the barrels start
their explosions at exactly at the same
time I want to offset the barrel to make
it look as if the first explosion sets
off this second Barrel so go ahead and
stop the Sim select the second source
and you can see it already has keys on
the out goinging velocity parameter
select those keys and move them to begin
at frame five the first key has the
outgoing velocity set at a value of
about
3,000 go to frame four and turn on auto
key set the outgoing velocity to zero so
that the barrel doesn't start exploding
until frame five and go ahead and turn
off auto key play The Sim and you can
see that the first explosion looks like
it's setting off the second one
now like any good pyromaniac let's add
more to this Fireball by blowing up the
third Barrel stop the Sim copy the
Second Source by shift dragging it like
so add the third Barrel to that new
source drag your timeline to see the Sim
now go ahead and turn off adaptive
degradation so you can scrub the
timeline a little bit faster go to frame
40 and offset the existing outgoing
velocity key frames to start at frame
frame 40 select the simulator and then
start the
Sim now I'll elapse just over 2 and 1/2
minutes and you can see as the first two
explosions begin to cool off there is a
third explosion that heats things up
again I'll elapse just over three more
minutes to get to this result and I'll
stop The Sim and now render a frame
let's say frame 70 and it looks pretty
cool select the simulator and set the
cell size to 0 015 M which increases our
total cells to about 4.6 million and go
ahead and restart the simulation for a
more detailed Sim I'll elapse about 6
minutes of simulation time to see this
final result in my sim here I get a
lovely simulation and a safe way to blow
up three barrels full of gasoline and
not burn my