How do you actually control the volume of fluid flowing from the source? I’m using temperature as the liquid source and set it to 1, and have been playing with the discharge value. It seems like you can increase it to some degree but it’s not predictable, and I can’t seem to get it lower than what I get with 1.
Even with discharge at .1 it seems same as at 1 or 10
See the vid clip below: the volume coming from the small emitter is pretty crazy. There are also some strange behaviours (seem weird to me anyway). THe stream of fluid breaks off into 2-3 streams at some point and doesn’t seem natural. The parameters should be visible on the left of the frame. I based these on experimenting with the values shown in that set of parameter variable videos on youtube.
Questions:
1) how to control fluid volume up and down?
2) how to get the fluid in this example to flow more like a normal (water/beer) kind of fluid?
I’m testing the fixed SPF approach indicated in another thread (and from the paint sample file). I can’t get a handle on how to employ the maximal step in combination with fixed SPF. Some specific (dumb user oriented) direction on that possible?
What exactly does SPF actually mean by the way? (I know it means ‘steps per frame’, but what does it mean in practical terms?)
I’m finding another odd thing: the liquid in my test is flowing down and then curving off to one side for no obvious reason. I have vorticity set to 0 for this one.
See the screen cap to see the motion.
How do I get it to flow more straight/with gravity?
- the liquid quantity is fully controlable with the discharge, that you said is fully unexplanable for me. if the discharge is very low the surface continues to release some small amounts of liquid (because of this stopping a source is a bit complicated) but with normal discharges the amount control is out of question.
- the weird behavior looks like preview problem, if you have very low value of the preview threshold, you will see the liquid vapours in the air and the simulation will look like this. but i will check your scene to see for other problems.
- if you force the spf value via the limits, the advection step (the maximal step) does not matter. each simulator has a value like SPF, PF has it and if i’m not wrong it is called “integration step” or something like this. in the most cases this value us an integer. the only difference between phoenix and the other simulators is that here SPF can be non integer and can be auto calculated from the velocity of the fluid.
- i suppose you have turned on the surface tension . honestly the surface tension has serios issues, i recomend to be not used yet.
I will send you my current file - I can increase the amount but I need to go a long way to see much difference (like 1 to 100 or even 1000) but going below 1 to reduce flow seems to have no effect.
- the weird behavior looks like preview problem, if you have very low value of the preview threshold, you will see the liquid vapours in the air and the simulation will look like this. but i will check your scene to see for other problems.
I unfortunately didn’t save that file separately as I meant to (continued playing and saved over it without thinking). At the moment that weird curving thing is not happening. If I get it to do it again I will save and send you the file. I don’t think it was just the preview though ,as it rendered that way too. Regarding the preview: how do you determine the “correct” range to show? The max is set by the source value (1 in most liquid cases I guess) but what about the min? A ton of my fluid disappears unless I set it to something like .001 or even .0001 Where should it be?
- if you force the spf value via the limits, the advection step (the maximal step) does not matter. each simulator has a value like SPF, PF has it and if i’m not wrong it is called “integration step” or something like this. in the most cases this value us an integer. the only difference between phoenix and the other simulators is that here SPF can be non integer and can be auto calculated from the velocity of the fluid.
- i suppose you have turned on the surface tension . honestly the surface tension has serios issues, i recomend to be not used yet.
Surface tension was certainly on, as was Viscosity. I’m really struggling to figure out the meaningful values there. ST seemed to need to be in the range of 1-4 but Viscosity was having a marked effect even at .01-.02 I think it would be very helpful to normalize the value range (behind the scenes) so that as much as possible the meaningful range of all parameters are within the same world (at least for ones that can be done for).
Realflow does have the integration step value, but it’s not something one has to mess with much in terms of shaping liquid - it’s more like an optmization thing in my experience, but I am not a huge expert by any stretch. More or less you played with the viscosity, surface tension, particle density/mass, stickiness (for interactions) and friction. The rest came down to forces and emitter shapes/animations.
Regarding the preview: looks like I don’t get that either I have some fluid that looked to be disappearing partway through the sim. The liquid is derived from temperature, and that is set to 1. Discharge is at 10 but that doesn’t seem to matter.
In order to see the fluid I have to actually set the preview at max 5 and min .01 - then I get roughly what shows in the render. Why would the preview need to show temps as high as 5?
usually the liquid preview is 0.5 - 2. values above 2 are unusual for the liquids, the values below 0.5 are invisible in the rendering (if the surface level is 0.5).
Those values are producing virtually nothing in my scene. At .5 there is amost nothing at all and at current I had to set it to .002 to get the full liquid to show up in the render. Surface level of .05 only seemed to work with a very lo-res sim, not sure why.
Just posted another screen cap. I have been playing around quite a bit with fixed SPF but the fluid behaviour just never seems quite right for the pour. I went back to Maximal Step of 5, and max/min of 5/2 (these values are just guesses really, I cannot really predict what will happen when I change them independently. When in fixed mode the result is far easier for me to anticipate).
Now the fluid behaviours seems kind of erratic. At the beginning it almost explodes out, then settles down into a smooth pour, then goes wobbly again. I have no idea at all how to control it anymore. Any pointers on what might cause this behavour? Vorticity is totally off now, as is viscosity, and surface tension is also off.
actually… that might not be classic. I’m having trouble keeping the input/output straight once the $implicit saving configuration gets broken. I think that may have been loading a an FT version… :roll:
So I redid it with Classic for sure, but I’m really getting some weird stuff. I was trying to experiment to see if using other channels than temperature would help the liquid. I tried smoke and fuel but was not getting anything at all.
However, if I set the Liquid to use Smoke it totally changes the way the *temperature* simulates. I get a *way* better result, but in order to see it I need to raise the preview max temperature up to something like 200 (even though it’s only at 1 in the Source object output).
The video shows the difference.
now the problem is that this nice smooth fluid won’t render - again, see the video.
- in my haste I made mistake in that video: when trying to show that the surface level wasn’t fixing the render problem I was adjusting the displacement amount by accident. It still doesn’t work with the surface level though.
To get anything but a solid block I have to put that level up around 200, which gives me a weird fluid inside the block. Higher than that and it just started getting more and more artifacted.
I did it both ways. The main point was that I got a much different flow of liquid out of the temperature when setting the liquid to “smoke”. It flows much faster and smoother. I’m unable to take advantage of it though, because if the liquid channel and the effects channel don’t match you get that solid rendering.
I’m trying to figure out how to get that nice smooth flow of liquid and still be able to render it.
Here is what I am gathering from all the testing on a pour shot so far:
- The docs and online stuff I could find indicated that it didn’t really matter which channel you choose for the Liquid source, but the choice of using Fuel, Temp, or Smoke as the Liquid source makes a big difference in the result/dynamics of the fluid.
- Temperature seems to provide the most “full” liquid. Fuel the most sparse and the most blobby (seemingly regardless of the settings used).
- If you try to render using one of the other (non-liquid source) channels for the Effects channel you can get a result, but it can be pretty unusable (too chunky, or in the case of Temperature it is basically a solid block that fills the Phoenix grid entirely).
If you look at the preview it really looks like the Liquid would almost need to use *all* the channels to get a nice full and smooth result. In the preview you can see the Temperature and Smoke particles interact and work around each other, so using one or the other as the effects channel makes for a lumpy/oddly shaped liquid mesh.
If I try to just use Fuel, and set Fuel as the liquid source and effects channel, I cannot seem to get a nice smooth and controllable flow of liquid. I’ve tried fixed SPF at all different values and nothing really looks very good.
I’m basically at a loss of where/how to push things along to get more than a simple gush of fluid from a simple emitter. I’m sure it’s mostly me - help please!
/b
I think first of all - phx not a particle based simulator and fluid sim part is still in beta stage Don’t expect fully controlable hi-end results. Maybe it would be best to just show us the result you are trying to achieve ?
P.S. I’ve tried to make very complex splash with phx - well, with realflow it was faster to get what I want/in lots of cases more logical (it is not a fire/smoke simulator at the end ), but still, implicit surfaces rullez the planet. Phx is faster and can easily burn ur water So, I think just post your realflow scene, with something you like and we will try to make the same result with phx. Or at least we try
Hey Paul -
I know it’s not a particle simulator, but what else do you call them? I figure particles gets the idea across anyway
I don’t have any real expectations yet for Phoenix (high or low). At this point I am trying to figure out what the expectations *should* be For sure it looks to be faster than Real Flow, but only if you can get something workable out of it…
I don’t want to really spend a bunch of time setting up a Realflow file to create a target. It’s not really apples-to-apples. I just want to be able to create a realistic shot of a pour into a glass. As soon as I tried to create one (rather than just use a pre-built scene like the beer.max) I ran into a lot of trouble. It’s not a super specific or crazy complex effect I want (not yet anyway )
The docs and online stuff I could find indicated that it didn’t really matter which channel you choose for the Liquid source, but the choice of using Fuel, Temp, or Smoke as the Liquid source makes a big difference in the result/dynamics of the fluid.
well, this sounds really scaring for me , and of course i made a fast test - fortunately the result with different liquid channel was exactly the same, until the last pixel. i suppose you setup was wrong, perhaps you forgot to disable the temperature in the source and this changes the result. do not forget that not only the liquid is simulated, the air is simulated too, and its temperature does matter.
in general, pour a glass is not too hard i think
- load the “liquid” preset (not the liquid-flowing!)
- create a source
- play with the SPF value and the “surface balance” parameter (not available in 1.2) to achieve stable settled liquid.
- add a gizmo to render smooth liquid-glass interface
), but still, implicit surfaces rullez the planet. Phx is faster and can easily burn ur water 