This page provides information on the Dynamics rollout for a FireSmokeSim object.
This rollout controls the FireSmoke dynamics parameters, which affect the fluid’s behavior when simulating. The Dynamics rollout can be accessed in the Modify panel when a FireSmokeSim object is selected. |
UI Path: ||Select Fire Smoke Simulator|| > Modify panel > Dynamics rollout |
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Example: Vorticity
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These options add random fluctuations in the fluid's velocity for each grid voxel. |
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The conservation process gives the fluid its characteristic swirling motion. It transforms straight-line movement of the fluid into swirling vortices. The higher the strength of the conservation, the farther the motion forces will be propagated throughout the container, so a movement in one point will cause the fluid to start moving at a distance too. The conservation directs smoke and fire into realistic shapes and helps liquids to support their own weight when at rest, and to fill up a volume they are poured into. |
Internally, the conservation updates the directions and magnitudes of the velocities of each cell in the grid, preparing them for the Advection step when the content will be moved between cells. Basically it tries to equalize the velocities coming in and going out from each cell, and does this in many passes, getting closer to the perfect equilibrium. The number of passes is the conservation strength (quality). In nature, conservation has an infinite strength and is always perfect. In Phoenix, the better the quality of the conservation is, the farther the movement from one point will be propagated, making the simulation more realistic, but at the expense of longer simulation time for each frame. There are a number of conservation methods in Phoenix that you can choose between, depending on the type of your simulation. Each of them comes with pros and cons for the given situation. |
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Example: Conservation Method Types
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Example: Conservation Quality
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Advection is the process that moves the fluid along its velocity inside the grid. A problem of all grid-based simulators is that moving the content of one cell to a new place in the grid will blur the result when the destination lies between cells (and it usually does), thus losing the fine details with each new frame. Phoenix has a number of advection methods that battle this problem in different ways, each with its own pros and cons depending on the situation.
Phoenix may perform advection more than once per frame, or once in a number of frames, depending on the Steps Per Frame (SPF) parameter. When you press simulate, the activity of the fluid in all of the voxels is calculated in sequential steps, representing the passage of time. The order of steps is always sequential, meaning the simulator will calculate fluid properties sequentially from one step to the next, until you have a series of steps that map out the fluid’s behavior over time. The number of steps can be modified using the Steps Per Frame (SPF) parameter, which determines how time is subdivided, and has a significant impact on the behavior, quality and performance of the simulation. |
To get the most detail for fire and smoke simulations, it is best to keep the Steps Per Frame (SPF) low. On the other hand, a higher SPF works better to keep liquid simulations smooth and steady, and can also produce better results for fast moving fluids in general. |
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Example: Advection Method Types
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Example: Steps Per Frame (SPF)
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Interaction between Active Bodies and the Phoenix Fire/Smoke Simulator is not supported yet. |
For more information on Active Bodies, please check out the Active Body Solver and the Active Bodies Setup Guide. |
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The main purpose of the Texture UVW feature is to provide dynamic UVW coordinates for texture mapping that follow the simulation. If such simulated texture coordinates are not present for mapping, textures assigned to your simulation will appear static, with the simulated content moving through the image. This undesired behavior is often referred to as 'texture swimming'. UVW coordinates are generated by simulating an additional Texture UVW Grid Channel which has to be enabled under the Output rollout for the settings below to have any effect. The custom UVW texture coordinates can be used for advanced render-time effects, such as recoloring of mixing fluids, modifying the opacity or fire intensity with a naturally moving texture, or natural movement of displacement over fire/smoke and liquid surfaces. For more information, please check the Texture mapping, moving textures with fire/smoke/liquid, and TexUVW page. |
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Example: Interpolation
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Example: Interpolation Step
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