Fluid Effects vs Fume FX

#121

how long did that take to sim on what kind of machine?

#122

LOL Wayne, I love that you comped that canon looking sim into a garden or porch. Like, this is my fireing my canon off my porch, LOL. Isn’t that all of our dream? Great sim tho.

#123

Yeah thats fantastic there, Im liking the transparency and nice velocity swirl, it looks like some toxic gas coming out of a drain pipe. What type of specs do you have on your hardware? My system chugs along but managed to cache out a 5GB.
@ your question, I couldnt get the volume axis to work. I had trouble with the whole timing thing and magnitude. I usually ended up blowing everything down first and had tro8ble to regather the temp and fuel back into a nice ball.

So instead Ive used another emitter and the motion field, seems to work.

#124

Azshall, thanks for the feedback. The res I used was not too bad, any higher would be a drag.

Howard, the sim took about 4 hours. I am currently using a dual quad core, BOXX with 8 processors.

David, …I was thinking the same think once I rendered the sim. Didnt feel like modeling an environment so I used a set I modeled some time ago. Chucked the big pipe in at the last minute. Seems quite hazardous with all those flowers laying around. Hehe.

#125

Thanks Jeremy,
I have a pretty strong system, but like yours it does not like to cache. It will, but takes forever. Expecially if my res in the hundreds. I normally wont have any problems if I cache 1 single file for the cache format. That’s a neat technique to set a negative boyancy then key the emission. I’m going to try that.

#126

In terms of simulation scale rate or more to the point dealing with really large explosions that grow slowly, is it better to build a higher resolution fluid to simulate a large explosion, or can you lower the sim scale rate down to 0.5 and try to adjust other attributes to get the effect you want?

Basically at the moment all I have is a big explosion but not really a nuke blast because it goes too fast. But Im finding that Im having to lower my sim scale rate down to below 1 to get the correct speed but then it completely changes the fluid, the explosion doesnt rise and kinda flattens out. Upping the bouyency would seem pointless as this would make the fluid faster, then maybe I need to increase fuel and temp attributes so that the explosion is hotter and therefore rise by itself and get bigger.

Is this the best plan of attack for this, or is it just easier to build a denser resolution fluid to achieve the same thing?

BTW Ive updated my previous explosion, slowing it down a bit, but for a nuke its still too fast I feel.

#127

You might try caching then retiming the cache. With Maya 2009 you should be able to simply retime the cache as a trax clip. With earlier versions you needed to cache as a single cache file and then reconnect to the currentTime attribute on the fluid from a new time node, then key the time values.
It does a linear interpolation between cache files, so it should still be smooth when you slow down. In general the simulation is optimal when the fluid moves about one voxel a time step. Simulating very slow motions can result in diffusion as can very fast motions( with highDetail solve the fast motions can also cause instability).

Duncan

#128

Thanks Duncan, Im on 2008 so ill give the keyframing the time node a go see how I go. I tried retiming the animation in Shake which worked to some degree but of course it tries to play one frame every 2 time steps and doesnt look quite right.

#129

Jeremy,
When creating a nuke I find success having a moderately high sim scale. Roughly between 1 and 2. The control of the smoke is defined by the bouyancy and the fuel emitter’s density/voxel/sec settings. I normally create a volume(sphere for my emitter) and then tweak the fluid drop off. Giving it a value between 2-4. This specifies how much the emission drops off as you move away from the volume axis. If you wanted more control you can use an omni and adjust your min max settings under the emitters basic attributes tab.

Regarding really large explosions its vital to have a sim scale over 1. Keep in mind as you increase your res and sim scale, the density emission rate may need to decrease. If the rate is too high the sims sometimes may break. I think Giap was having this issue. If the movement of the nuke is too agressive, trying a low sim scale may work. But this is where bouyancy can come in quite handy acting as an igniter. I normally have bouyancy keyed for only 5 frames, letting the sim scale drive the motion.

High Detail Solve set to all grids is helpful, there’s more detail in the movement of the smoke, resulting in a nicer sim. I noticed you mentioned increasing feul and temperature attributes. I don’t normally use feul. Only temperature here. But I have seen some nice sims with feul being used. I think you can play with feul scale to multiply the strength of the explosion if you take the feul route. I also stay away from turbulence keeping it non existant in my container. If I need more turbulence I would use fields. Hope this helps.

#130

^^^^^ Thanks tokanohanna, there are some useful tips there, I didnt even think about keying the bouyency to zero, also I assumed you were using fuel which goes to show you dont necessarily need it and it would probably speed up the caching process a little bit too!

As for the turbulence, do you use any temp turbulence at all?

thanks again :]

#131

Keying bouyency is a great way to control the sim. Your right about caching, definetely saves time.

I don’t use any temp turbulence. If any it’s normally .01-.03. Turbulence I think is can be the containers enemy at times. I have found that it does work great when trying to sim rocket engine or shuttle smoke. If you want soft dissipating smoke, then turbulence can cause problems. Creating nukes can be difficult if turbulence is too high as well.

#132

I’m actually sitting here at work tweaking robozyt’s flamethrower a little just to see where i can put it in a little bit of time i have in between some work junk today. i hope you dont mind. i’ll post something when i get a render.

aside from that i was looking at some flamethrower references like this one
Flamethrower-Real-Life

#133

This I made with Maya fluids.
http://www.youtube.com/watch?v=VjFuqoFqMSM
resolution 100х200х100

http://www.youtube.com/watch?v=b5pRjnVU2W8
resolution 90х180х90

I don't spend much time with fluids but I think it is more efficient way to achieve the good result is looking for Numeric display and than make some adjustments in shading & texturing TAB.When understand what is going on . than the result been more predictable.
#134

this is kinda re the tornado example from a few posts back. I was re-reading one of Ducan’s blog posts and he said this,
“Another method that can be very controllable is to keyframe the rotation of a drag field that has a magnitude around 10 and inherit motion set to 1.0.”
so simple and works really well w/o getting crazy, maybe this plus the volume axis field… but do a simple test and you will see how simple this is to do specific movements.
I added this expression to the drag field to make fome some more interesting motion

dragField1.rotateY = time*360;
  dragField1.rotateX = (sin(time*2))*10;
  dragField1.rotateZ = (cos(time*2))*10;
#135

looks interesting there, will try that expression and see how it goes.

heres my attempt at flame thrower…

http://www.vimeo.com/3876162

#136

I think I’m going to try that expression myself. The flamethrower is Brilliant!!! Sweet sim Jeremy.

#137

Somebody know how to make fluid emission travel by object like in first post (piece of wood burn)?

#138 
Theres a piece of code you need to build in a compiler that allows you to emit fluids from a texture, ie allowing you to emit from white from an animated ramp for example. This is called "simpleFluidEmitter" and can be found in the devKit > plugins folder in your Autodesk application folder. Goodness knows why its not in the fluids menu?!

With a few basic mel commands you can hook it up and make magic!
I pulled off a simple demo here… http://www.vimeo.com/3879228

Cheers Tok for your comments! ;=]

#139

Hey Folks,

   I hv been quite inactive to this thread from last week coz of poor health & mentally sick with health & also by animal abusers but I have been watching this thread activity quite closely,
   You guys rock!! this is becoming like a 2nd FLuid Smoke thread with loads of tricks & tips. My learning curve is rising subsequently.
   
   I like tokanhanna`s test its a masterpiece. being Inspired by him I made a couple of quick test but its a first try I will polish it later with more elements. C&C are welcome :
   
   plz have a look at :
   
   [http://www.youtube.com/watch?v=9SqKJVwcBqM](http://www.youtube.com/watch?v=9SqKJVwcBqM)
   [http://www.youtube.com/watch?v=M-oDXkCOkpQ](http://www.youtube.com/watch?v=M-oDXkCOkpQ)
   
   or for better resolution  have check with :
   
   [http://www.vimeo.com/3878442](http://www.vimeo.com/3878442)
   [http://www.vimeo.com/3878503](http://www.vimeo.com/3878503).
   
   I`ll upadate more for this thread by this weekend.

   ok!

I know this is not place to share personal views instead of techincal views & tricks, But I cannot stop myself to express my thoughts.
Millions of animals being slaughtered everyday. Do they dont have rights to live?
I know I m not talking anything new here but keeping global warming & animal extinction in mind It makes me to do sumthing for the welfare of animals.
I think that all animals should be free and that humans don't give a crap about them. People think that animals don't expierience physical and emotional pain but they are far more like us than everyone thinks and everyone should know that. We need to fight against animal cruelty and let animals be free. I think animals would be a lot better off if no human ever ate meat because we're not carnivores and we can live without meat.

Anyway my idea is to create awareness thru our medium as we deal a lot with nature & wild. their are many others who have created awareness & expressed their views thru their art & skills. plz have check with these links : plz watch every part of it.
& let me know if we can do anything to bring a change in every one of us.

[http://www.youtube.com/watch?v=fLyppFpfuM8&feature=related](http://www.youtube.com/watch?v=fLyppFpfuM8&feature=related)
[http://www.youtube.com/watch?v=JqXu3XH_1wI&feature=related](http://www.youtube.com/watch?v=JqXu3XH_1wI&feature=related)
[http://www.youtube.com/watch?v=7rRWLTGSNvg](http://www.youtube.com/watch?v=7rRWLTGSNvg)
[http://www.youtube.com/watch?v=q5dU1kA4KBg&feature=response_watch](http://www.youtube.com/watch?v=q5dU1kA4KBg&feature=response_watch) & many more...

I apologize for writing a lenghty mail But I culdnt to stop myself to express my views.
Thnxs much for reading this.
I m just a enthusiast.
Vikas
#140

eeeek. while your hearts in the right place, that could easily be a thread killer.

I like your texturing - I think fluid texturing is such a hard thing to get right - I really hate when fluids look overtextured and it distracts from the actual simulation itself. Were those rendered in the hardware render buffer?

I’m going to have to pull my finger out and make the effort this weekend to get some work up in this thread.