Tips and Tricks: When we use From Field or From Particles.

Hi,

A big question when we are simulating a GridFluidDomain in RealFlow, is how to know when we can use “From Field” or “From particles” from the Surface tab  “Source to” parameter. Actually you can use “from field” or “from particles” when you want, but there is a difference between them and the simulation might be affected depending what you choose.  I’m going to put 3 images to explain it.

1- When you are simulating a GridFluidDomain, you should put the “Source to” parameter to “From Field”, make sure you have the checkbox checked in the Export Central to export these files, and the “Calculate surface” parameter to Always to calculate it.

Simulating_the_gfd_using_from_field_and_Calculate_Surface_Always

Simulating_the_gfd_using_from_field_and_Calculate_Surface_Always

2- Why do I need to use “From field” instead of “From particles”? Because when simulating splashes and foam particles, the splash won’t need to calculate it again and the field files will be read from the cache, and the simulation will be faster than using “from particles”. So we need to put the “Calculate surface” parameter in the GridFluidDomain to cache when simulating splashes or foam. The GridFluidDomain must be in cache mode too.

Simulating_the_splash_using_from_field_and_Calculate_surface_cache

Simulating_the_splash_using_from_field_and_Calculate_surface_cache

3- Once the splashes and foam have been calculated, we want to calculate the GridMesh for the GridFluidDomain. In this case, we’ll use “From particles”. Why? Because “From particles” adjust better the mesh to the particles than using “From particles”. Before calculating the mesh we need to put the “Calculate surface” parameter to Always to calculate the new field file for the “From particles” and change the Source to “From particles”. If you don’t change the “Calculate surface” parameter from cache to Always, the mesh will  be generated with the old files which have the “From field” information.

Simulating_the_GridMesh_using_from_particles_and_Calculate_surface_always

Simulating_the_GridMesh_using_from_particles_and_Calculate_surface_always

luisM.

18 comments

  1. Thanks good tips.
    I have understood that the Surface with “From Field” is different from “From Particles”.
    If I need high precision,do I need to calculate all of simulation with “From Particles”?
    Is From Filed based on volume of GFD?
    Is From Particles based on particle positin of GFD?
    If I am right,When I use different source, I think that Splash and foam particles doed not match mesh surface.

      1. Hi,

        If you are not using the filter to relax the mesh, splash and foam should match the mesh surface. It they are not working there is something in the scene which is causing this. Don’t forget to put the Calculate surface to Cache once you have simulated the GFD and before simulating the splash and foam.

        luisM.

  2. Hi,
    I am doing a simulation of a river using hybrido.
    somehow am getting a very stingy mesh
    i am also using a noise field and animated the time scale
    which is giving me a variation in the flow
    does this happen often ?

    my grid fluid is 283*58*371 in size
    resolution is 6000000
    density 2000
    particles sampling 4

    grid mesh is been calculated with
    threshold .2
    sourch -from particles

    cell size .2
    Thanks

    1. Hey!
      Try to modify the Autocell size and Auto Bandwith manually. You said you are putting a 0.2 for cell size. Try to put a low value as 0.06.

      luisM.

  3. I’m not understand this process like and Saka.🙂
    If we calculate all stuff with “from field” and then at the end switch to “From particles” the foam and splash repeat the surface of “from filed”.
    I this video “RealFlow 2012: Hybrido2012 part 1” at the end we see compare of this two methods(colorized pictures). And they not match. By logic way the foam need to know the surface where it need to lay, so it look to the “from filed” mesh when it calculated.
    Can You make a short video or explain more how that work ?

    Thanks!

    1. Hi Igor,

      Of course, but you can mesh the gridmesh with “from field” as well if you want, but the mesh will have less detail than using by particles. Using “from field” or “form particles”, the foam must be perfectly adapted to the surface if not are using an extra filter for the mesh. It due to the foam is placed on the main fluid surface and the gridmesh keeps this information too. To mesh, From particles, is useful when you have a lot of droplets which are far away from the main fluid surface and you want to mesh them.

      luisM.

  4. Actually was using wind field ,which i forgot to mention
    also when i add my emitters with the domain to my Grid mesh
    it gave me lot more detail
    thanks a ton
    will trouble you more in future😉

  5. Hi,
    I was wondering if it is wise to add emitter node in grid mesh??? I got lot of strange artifacts on my mesh after adding it… but however i got a good volume and the stringiness of the mesh seem to vanish.

    1. Hi Raul,

      It depends what you want. It if is working in this way for you, it will be cool. But, as you said, you might be you had strange artifacts on your mesh and they can’t be fixed independently for that emitter. But you can apply relax filters to remove the artifacts.

      luisM.

      1. Hi,
        The auto radius and the smooth did not have any effect once the emitter node was inserted in the mesh is that normal? However the filter did get rid of the artifacts a lot .Thanks a lot for the tip, I would not have figured that out on my own.
        Thanks

      2. hey,

        Are you sure when you are building the mesh, that you are putting the “Calculate ….” parameters for the surface tab by selecting the grid domain to “Always”?

        luisM.😉

      3. Hi,
        The calculate surface is on, in the domain … Only the auto radius and smoothing is not working .. It was making the mesh even after the radius was put to 0. However i did manage to control the mesh through filters…atlest for this shot.
        Thanks.

  6. Sir i like ur blog,work very much . I want one adwise from u to
    make splace with normal particle system in real flow . But i cannot
    achiv crown splash .my satup of scene like an ice cube is falling in to
    glass of water so can u help me to solve this .

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