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Phenomenological Simulation of Brooks

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If CFD had to be used. Very thin resolution, large ... [MWM87,TDG00,Aret ] iMAGIS-GRAVIR / IMAG. Relying on phenomenological simulation. Primitives based: ... – PowerPoint PPT presentation

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Title: Phenomenological Simulation of Brooks


1
Phenomenological Simulation of Brooks
  • Fabrice Neyret Nathalie Praizelin
  • iMAGIS / GRAVIR - IMAG

iMAGIS is a joint project of CNRS, INRIA,
INPG and UJF.
http//www-imagis.imag.fr/
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If CFD had to be used
(Navier-Stokes)
FM96,97,...
  • Very thin resolution, large domain ( and
    stability ? very small dt )
  • Very non-linear equations (shockwaves, surf.
    tension)
  • ? Hard and long system solving
  • Unknown parameters (e.g. boundary conditions)
  • Visible features are emerging phenomena ?
    Hard to control
  • while
  • Water motion is not directly visible
  • Strong a priori knowledge on the result
  • Users want some control

5
If surface wave simulation had to be used
FR86,P86,GS97
  • Very thin resolution, large domain
  • Very non-linear equations (waves trigger waves)
  • Hard and long system solving
  • while
  • Strong a priori knowledge on the result

6
If Fourier synthesis had to be used
MWM87,TDG00,Areté
  • Very thin resolution, large domain
  • Non-linear phenomena
  • Non uniform wave propagation(variable depth,
    obstacles)
  • ? Statistical models are helpless
  • while
  • Strong a priori knowledge on the result
  • Users want some control

7
Relying on phenomenological simulation
  • Primitives based
  • Geometric construction of visual features
  • Choice of the primitives of visual interest
  • User can control the primitives
  • Vector primitives independent from
    rendering resolution
  • Fast, high resolution, large domain

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  • Phenomena that are out of scope

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Wave theory
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Wave theory
capillary waves cg gt cw
shallow water cg cw
gravity waves cg lt cw
14
Typology of stationary waves
non dispersive case cg cw c ? shockwave
15
Froude waves - shockwaves calculation
(Froude number)
(slope)
16
Froude waves - shockwaves calculation
17
The chosen primitives
18
Our approach
  • 1. Get a stationary velocity field (low res is
    ok)
  • 2. Build the primitives skeletons
  • 3. Add field perturbations WH91
  • 4. ( Build a surface and render )

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1. Get a stationary velocity field
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1. Get a stationary velocity field
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1. Get a stationary velocity field
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1. Get a stationary velocity field
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2. Build the primitives skeletons
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2. Build the primitives skeletons
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3. Add field perturbations
  • WH91
  • Small support fields (vortex,source)attached on
    particles (passive floaters)

28
3. Add field perturbations
  • A perturbation needs time to propagate
  • We cannot simply apply the static construction !
  • A node moves if
  • V changes locally
  • the previous node has moved

perturb V gtgt
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3. Add field perturbations
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Conclusion - limitations - future work
  • A real-time simulation of (some) animated visual
    features of brooks !
  • Vectorial construction (no grid sampling)
  • Perturbations can be random, procedural (von
    Karman),or user generated.
  • Fade and stop the primitives.
  • Adaptive capillary ripples.
  • Define a rendering method ! (producing a surface
    ?)
  • Hydraulic jumps, foam, ...

31
Phenomenological Simulation of Brooks
  • Fabrice Neyret Nathalie Praizelin
  • iMAGIS / GRAVIR - IMAG

iMAGIS is a joint project of CNRS, INRIA,
INPG and UJF.
http//www-imagis.imag.fr/
32
  • Le détail des mouvements est complexe

33
Exploite-t-on toute la connaissance disponible ?
  • Il y a de grandes régularités dans les scènes
    naturelles !
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