=Paper=
{{Paper
|id=Vol-2732/20200909
|storemode=property
|title=Fluid Flow Modeling in Houdini
|pdfUrl=https://ceur-ws.org/Vol-2732/20200909.pdf
|volume=Vol-2732
|authors=Oleksandr Holub,Mykhailo Moiseienko,Natalia Moiseienko
|dblpUrl=https://dblp.org/rec/conf/icteri/HolubMM20
}}
==Fluid Flow Modeling in Houdini==
https://ceur-ws.org/Vol-2732/20200909.pdf
Fluid Flow Modelling in Houdini
Oleksandr Holub, Mykhailo Moiseienko[0000-0002-4945-202X]
and Natalia Moiseienko[0000-0002-3559-6081]
Kryvyi Rih State Pedagogical University, 54 Gagarin Ave., Kryvyi Rih, 50086, Ukraine
n.v.moiseenko@gmail.com
Abstract. The modern educational environment in the field of physics and
information technology ensures the widespread use of visualization software for
successful and deep memorization of material. There are many software for
creating graphic objects for presentations and demonstrations, the most popular
of which were analyzed. The work is devoted to the visualization of liquids with
different viscosity parameters. The article describes the development of a fluid
model in the form of a particle stream. The proposed methodology involves using
the Houdini application to create interactive models. The developed model can
be used in the educational process in the field of information technology.
Keywords: Fluid Flow, Modelling, Houdini.
1 Introduction
Computer graphics today is one of the main directions of information technologies, that
develops most stormily. By means of computer graphics it is possible to do visible or
visualize such phenomena and processes that cannot be seen in reality, it is possible to
create evident character of that in actual fact has (for example, effects of theory of
relativity, conformity to law of numerical rows and others like that) unobvious [1; 9].
Scientific visualization that sometimes is briefly named by SciVis is graphic
representation of data as to the means for a study and understanding of data. Sometimes
such method is named the visual analysis of data. It allows to the researcher to get an
idea about the system that is studied, before by impossible methods. Scientific
visualization differs from graphic representation. Graphic presentation is created first
of all for an information and results transfer by methods that it easily to understand [8].
In scientific visualization prevails aspiration to understand data. However often both
methods combine.
In terms of calculations, SciVis is a part of the visualization which includes the
research in computer graphics, image processing, high-efficiency calculations and
others. SciVis tools can also be used to game design, computer animation, multimedia
presentations etc. [5; 6]
Copyright © 2020 for this paper by its authors. Use permitted under Creative Commons License Attribution 4.0 International (CC BY 4.0).
2 Literature review
Programming tools that allow to create 3D graphic arts, design the virtual reality objects
and create the simulated images are very diverse. Firstly, a comparative analysis of the
platforms for the creation of AR was carried out. The most popular tools – Autodesk
3ds Max, Autodesk Maya, Blender 2.8 and Houdini – were analyzed (Table 1).
Table 1. Comparison of modeling tools
Modeling Autodesk 3ds Autodesk
Blender 2.8 Houdini
tools Max Maya
Developer Autodesk Autodesk Blender Foundation Side Effects Software
Windows, Windows, macOS, Linux,
Operating Windows, macOS,
Windows macOS, Amiga OS, Haiku, Morph
system Linux
Linux OS
C, Maya
Programming Embedded
C, C# Python C
languages Language,
Python, C#
Procedural Texturing,
Scripting, HD-Rendering, Modeling, Terrain,
Animations, Texturing, Character, Animation,
Rendering with graphics Solaris: Layout Tools,
card, 3D Sculpting, Solaris: Lookdev &
3D modeling, Portable, Customizable, Lighting,
Texturing,
Animation, Video overlay, Realistic Mantra/Karma
3D
Rendering viewport, Motion Rendering,
Features Sculpting,
software for tracking, Parametric Compositing,
Keyframe
games, Design Modeling, 3d sketching, Volume, PDG | Tasks,
animation
visualization Real time rendering, Pyro FX, Fluids,
Texture painting, Rigid Bodies,
Lightweight, Physically- Particles, Crowds,
Based Rendering, VELLUM Cloth,
Compositor, Keyframe Wire Dynamics
animation
Commercial, free
Model of
Subscription Subscription Free, Open source version for students,
pricing
artists and hobbyists
Autodesk 3ds Max [3] – professional software for 3D modelling, animation and
visualization, which is actively used by game designers. 3ds Max allows to create
massive worlds in games, visualize high-quality architectural renderings, model finely
detailed interiors and objects, and bring characters and features to life with animation
and VFX.
The hundreds of 3ds Max Access plugins uses both direct manipulations and
methods of procedural design, and the enormous library of industry leading 3rd-party
plugins highly facilitates a design process.
3ds Max offers the professional set of tools. Nevertheless, students can get software
free of charge, and a trial version is also accessible in during 30 days.
Autodesk Maya is the 3D graphic arts editor, accessible on Windows, macOS and
Linux. Maya gives an industrial power by a concurrent price. Maya is perfect for design,
texturizing, illumination and rendering: a large set of functions includes the
manipulations particles, hair, fabric, solids, as well as fluid simulations and animations.
Today, Maya is one of the best 3D toolkits at the world market.
Blender 2.8 is a public domain open source computer graphics software of
professional functionality. Blender is best in design, texturizing, animation and
visualization. The long-awaited version 2.8 provides a modern intuitive interface,
interactive real-time reflection with an enormous amount of corrections and new
features [2].
Previous Blender versions have often been criticized due to non-friendly to
beginners. Especially dissatisfied there were those who switched from other 3D
packages (3ds Max, Maya etc.), because the Blender’ design principles and hotkeys
don’t comply with the industrial standards and user expectations.
SideFX Houdini is a professional programmable package to make a 3D graphic art.
Houdini is rather a visual programming environment than classical 3D CAD as
mentioned above. Houdini provides to the digital artists a power, flexible, and
controlled node-based procedural environment with a lot of industrial-grade visual
effects to create high-quality physical 3D animations (Fig. 1). Like Maya and Blender,
this powerful and non-standard workflow can be tricky for beginners, so Houdini also
provides a set of traditional visual tools [4].
Fig. 1. Houdini FX interface
SideFX offers Houdini Apprentice, a free version of Houdini FX, that students, digital
artists and amateurs can use for the personal noncommercial projects. Houdini
Apprentice gives access to almost of all Houdini FX features. The full-featured Houdini
Indie is an affordable commercial option for small studios.
Houdini is mainly used for realistic physical simulations (e.g. particles dynamics),
procedural modeling, animation, effects, rendering, and compositing.
To work with Houdini, you need to understand the basic principles of procedural
modeling – a number of computer graphics methods for creating 3D models and
textures. Procedural modeling is often used to create 3D models of complex shapes
(plants, architecture building).
With the features provided by Houdini, you can build models, objects, simulations
and customize them, and test their performance by running and testing simulations
directly in the Houdini editor.
3 Results
We made the simulation of liquid streams (fluid flows) in Houdini. First you had to
create an object that will be the source of stream. We chose a sphere primitive and
added node transforms that allow you to change such sphere parameters as size and
position (Fig. 2).
Fig. 2. Sphere and its node transform
In order to visualize how a liquid with different viscosities will flow down over
surfaces, it is necessary to add another object that will simulate such a surface (Fig. 3).
Fig. 3. Object with inclined surface and container
Then we changed the size and position of sphere by node transforms so that the sphere
is above an inclined surface (Fig. 4).
Fig. 4. Placing a sphere above the surface
To add to the sphere properties a source of the node particles, which will simualte the
liquid stream, we used flipsource nodes and DOP Network (Fig. 5).
Fig. 5. flipsource nodes and DOP Network
The DOP Network node contains another network of nodes (flipsolver), which is
responsible for creating particles (Fig. 6).
After connecting the flipsolver network to the sphere, you can see a cloud of particles
formed around the sphere only (Fig. 7). In order to imitate the fluid flow behavior, it is
necessary to connect the flipsolver network to the gravity node. This will cause particles
to fall vertically down (Fig. 8 а). Starting the simulation, you can see that particles
behavior will be similar to liquid stream behavior (Fig. 8 b).
Fig. 6. flipsolver network
Fig. 7. The result of the flipsolver network action to the sphere
But now the particles only fall down within a given area and do not interact with a
surface that was added before anyway. To enable the fluid-surface interaction, it is
necessary to add a static object to the flipsolver network, namely staticobject and
staticsolver nodes (Fig. 9).
Starting new simulation, you can see the physically correct fall of the particles, and
how they flow from an inclined surface into the container (Fig. 10). At this stage, the
particle stream simulates a liquid without viscosity, temperature or density. You can
add these properties in the flipsolver network settings window. We set the Viscosity
parameter to 100 (Fig. 11).
a b
Fig. 8. Gravity node (a) and its action (b)
Fig. 9. staticobject and staticsolver nodes
Fig. 10. Particle flow simulation
Fig. 11. Fluid physical parameter settings window
Running simulation again, you can see how the Viscosity parameter affects the fluid
flow behavior. The stream flows from the surface much slower and looks like a viscous
substance such as honey (Fig. 12).
Fig. 12. A simulation of particles stream with the non-zero viscosity parameter
The behavior of liquids with different viscosity is shown on Figure 13.
Fig. 13. Modelling liquids with different viscosity
4 Conclusions
1. The use of programmable environments like Houdine to create physically correct 3D
models has a deep impact on both the science education and CS education. This
makes learning visual and fun. Using the proposed software and the implemented
models to make the simulated animations is more effective than using traditional
experiments and pre-recorded video.
2. Learning using interactive 3D models in a mixed environment can be useful for a
deeper understanding of the simulated processes, so our further research will be on
the VR/AR using to facilitate training the bachelors majoring in CS.
References
1. Adair, D.: Incorporation of Computational Fluid Dynamics into a Fluid Mechanics
Curriculum. In: Liu, C. (ed.) Advances in Modeling of Fluid Dynamics. IntechOpen,
London (2012). doi:10.5772/39217
2. Blender Developers Blog - Developer musings on Blender. https://code.blender.org (2020).
Accessed 21 Mar 2020
3. Creative Bloq Staff, Jarratt, S.: The best 3D modelling software in 2020,
https://www.creativebloq.com/features/best-3d-modelling-software (2020). Accessed 11
Jun 2020
4. Getting Started | Learning Houdini Learning Path | SideFX.
https://www.sidefx.com/learn/getting_started (2020). Accessed 21 Mar 2020
5. Haranin, O.M., Moiseienko, N.V.: Adaptive artificial intelligence in RPG-game on the
Unity game engine. In: Kiv, A.E., Semerikov, S.O., Soloviev, V.N., Striuk, A.M. (eds.)
Proceedings of the 1st Student Workshop on Computer Science & Software Engineering
(CS&SE@SW 2018), Kryvyi Rih, Ukraine, November 30, 2018. CEUR Workshop
Proceedings 2292, 143–150. http://ceur-ws.org/Vol-2292/paper16.pdf (2018). Accessed 31
Dec 2018
6. Katsko, O.O., Moiseienko, N.V.: Development computer games on the Unity game engine
for research of elements of the cognitive thinking in the playing process. In: Kiv, A.E.,
Semerikov, S.O., Soloviev, V.N., Striuk, A.M. (eds.) Proceedings of the 1st Student
Workshop on Computer Science & Software Engineering (CS&SE@SW 2018), Kryvyi
Rih, Ukraine, November 30, 2018. CEUR Workshop Proceedings 2292, 151–155.
http://ceur-ws.org/Vol-2292/paper17.pdf (2018). Accessed 31 Dec 2018
7. Kuznietsov, V.S., Moiseienko, N.V.: Development graphic shell for the program
calculations of physical properties of solids. In: Kiv, A.E., Semerikov, S.O., Soloviev, V.N.,
Striuk, A.M. (eds.) Proceedings of the 1st Student Workshop on Computer Science &
Software Engineering (CS&SE@SW 2018), Kryvyi Rih, Ukraine, November 30, 2018.
CEUR Workshop Proceedings 2292, 156–161. http://ceur-ws.org/Vol-2292/paper18.pdf
(2018). Accessed 31 Dec 2018
8. Lytle, S.: Top 10 Benefits of 3D Visualization. CivilFX. http://www.civilfx.com/benefits-
3d-architectural-visualization (2016). Accessed 21 Mar 2020
9. Vad, J., Lajos, T., Schilling, R.: Modelling Fluid Flow: The State of the Art. Springer,
Berlin, Heidelberg (2004). doi:10.1007/978-3-662-08797-8