Domain Stats Settings
This page documents the statistics info for the Domain FLIP Fluid Stats panel.
| Info Display Mode | The type of simulation stats/info to display. Cache Info Display stats/info about the entire simulation cache. Frame Info Display stats/info about a specific frame. |
| Frame | Frame number to use when the Info Display Mode is set to Frame Info |
| Lock to Timeline | Lock the Frame setting to the current position in the Blender timeline. This setting is only active when the Info Display Mode is set to Frame Info |
| Export to CSV | Export the simulation stats/info as a CSV file. Warning: this feature is out of date will not contain all of the simulation statistics that are currently available. |
Statistics for when the Inflow Display Mode is set to Cache Info. This view will display stats for the entire cache.
| Completed Frames | The current number of completed frames and total number of frames in the current simulation. |
| Start Frame | The starting timeline frame of the simulation cache. This is the first frame on the timeline that the simulation results will be available. |
| End Frame | The ending timeline frame of the simulation cache. This is the last frame on the timeline that the simulation results will be available. |
| Average Performance Score | Displays the average performance score across all frames of the cache. For more information on performance score, see Performance Notes > Performance Score and Measuring Performance. |
| Estimated Time Remaining | Estimation of how much time is remaining in the current simulation. This is a very rough approximation based upon on the compute time of previous frames and may not reflect the actual time remaining. This setting is only displayed if a simulation is currently running. |
Statistics for the major solvers of the simulator. Currently this includes the pressure solver and viscosity solver if enabled. This section can be viewed to see a summary of the solver status.
| Solver Failures | The number of times that the solver has failed out of the total solving steps run in the simulation. It is okay and normal for the solver to fail infrequently, but if it is failing on multiple consecutive frames, this may result in an unstable simulation. To reduce the chance of a solver failure, or to stabilize a simulation where the solver is failing frequently, increase the number of minimum substeps. Related topic: What are substeps? |
| Max Iterations | The maximum number of iterations that the solver ran during a solving step in the simulation. The frame at which this maximum occurred is also displayed. |
| Max Error | The maximum amount of estimated error resulting after a solving step in the simulation. The frame at which this maximum occurred is also displayed. |
| Max Stress | The maximum amount of stress experienced by the solver during a solving step in the simulation. The frame at which this maximum occurred is also displayed. A stress value over 80% is considered high stress and once this value reaches 100%, the solver can fail which can result in an unstable simulation. To reduce the amount of stress, increase the number of minimum substeps. Related topic: What are substeps? |
- Solver Failure - When the solver iterations meet the maximum number of iterations (or when the stress level reaches 100%), the solver may fail, meaning that it has not found a suitable approximation to the fluid physics equations. It is normal and okay for a solver to fail infrequently and is sometimes unavoidable. However, if the solver fails frequently and on multiple consecutive frames, this can indicate that the simulation is too complex for the current settings. The solution to reduce solver failures is to increase the number of simulation substeps during a frame (What are substeps?).
- Solver Iterations - The solvers approximate fluid physics equations by running calculations in a loop repeatedly, with each loop refining the solution until the solution is "accurate enough". Higher iteration numbers lead to longer simulation times and can mean that the solver is having difficulty finding a solution. Increasing substeps (What are substeps?) can help the solver find a solution within a lower number of iterations. When the max iterations is reached, this can mean that a solution was not found, and can also sometimes mean that no solution exists. This is what is meant when the solver fails. The amount of iterations is capped to some maximum otherwise the simulator could spend way too long trying to solve the problem or possibly take an infinite amount of time if no solution exists. The maximum number of solver iterations can be increased in the Domain > Advanced Settings > Simulation Stability menu.
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Solver Stress - The stress level is measured as the number of solver iterations over the maximum allowed solver iterations and is displayed as a percentage value. A value over 80% is considered high and once this value reaches 100%, the solver may fail.
- Higher resolution simulations and simulations with more liquid generally result in higher solver stress levels.
- The viscosity solver is much more likely to reach high stress levels compared to the pressure solver due to the nature and complexity of the calculations involved. Using variable viscosity features will often increase the amount of stress by a large amount.
- Symptoms of an unstable viscosity simulation can be stuttering fluid motion, viscosity not being applied, fluid suspended in air, or other unexpected behavior.
- Increasing simulation substeps will often be required to keep variable viscosity simulations stable. We would recommend increasing the minimum substeps to around 2 - 4 to start with, or higher depending on the complexity of the simulation.
- Factors that can increase viscosity solver stress are: higher resolutions, larger differences between viscosity values, higher amounts of fluid motion, complexity of simulation (complex obstacle geometry and/or rapid motion of obstacles), and lower frame rates.
- Estimated Error - This number is the estimated amount of error of the found solution compared to a "perfect" solution. These numbers are usually small. If the max iterations is reached and the number is large (such as greater than 10.0), this usually indicates that a solution did not exist.
| Simulation Stage | The stage of the simulation calculations to display timing info about. The simulator runs dozens of different simulation calculations during a frame. These calculations are categorized into a few separate simulation stages. See Simulation Stages. |
| Percentage | The proportion of time spent calculating a Simulation Stage for all completed frames. |
| Time | The cumulative time spent calculating a Simulation Stage for all completed frames. |
| Total | The cumulative computation time of all completed frames. |
| Mesh Type | The type of mesh to display info about. See Mesh Types. |
| Size | The cumulative file size of all meshes of Mesh Type for all completed frames. |
| Total | The total file size of all meshes for all completed frames. Notes: this value is not the total file size of the simulation cache and is only the file size of the data that is generated by the simulator. The cache will also store other types of data for managing the simulation that is not accounted for in the simulation statistics. For an accurate cache size, view this information using the filesystem of your OS. Typically, the difference between the total mesh size and the total cache size is not significant. |
Statistics for when the Inflow Display Mode is set to Frame Info. This view will display stats for a specific frame of the simulation cache.
| Frame ID | The simulator frame ID number. The ID value starts counting at frame 0. |
| Time Step | The incremental change in simulation time over the entire frame measured in seconds. |
| Substeps | The number of substeps computed during the frame. Related topic: What are substeps?>. |
| Fluid Particles | The total number of fluid particles at the end of the frame computation. |
| Whitewater Particles | The total number of whitewater particles and number of each foam/bubble/spray/dust particle type at the end of the frame computation. |
| Performance Score | Displays the performance score for the current frame. For more information on performance score, see Performance Notes > Performance Score and Measuring Performance. |
Statistics for the major solvers of the simulator. Currently this includes the pressure solver and viscosity solver if enabled. This section can be viewed to see the solver status during a frame.
For additional notes and information on the solvers, see the topic above: Additional Solver Notes.
| Solver Status | Whether or not the solver succeeded or failed during this frame. It is okay and normal for the solver to fail infrequently, but if it is failing on multiple consecutive frames, this may result in an unstable simulation. To reduce the chance of a solver failure, or to stabilize a simulation where the solver is failing frequently, increase the number of minimum substeps. Related topic: What are substeps? |
| Iterations | The number of iterations that the solver ran during this frame. |
| Estimated Error | The amount of estimated solver error during this frame. |
| Stress Level | The maximum amount of stress experienced by the solver during this frame. A stress value over 80% is considered high stress and once this value reaches 100%, the solver can fail which can result in an unstable simulation. To reduce the amount of stress, increase the number of minimum substeps. Related topic: What are substeps? |
| Simulation Stage | The stage of the simulation calculations to display timing info about. The simulator runs dozens of different simulation calculations during a frame. These calculations are categorized into a few separate simulation stages. See Simulation Stages. |
| Percentage | The proportion of time spent calculating a Simulation Stage during the frame. |
| Time | The time spent calculating a Simulation Stage during the frame. |
| Total | The total computation time for the frame. |
| Mesh Type | The type of mesh or mesh data to display info about. See Mesh Types. |
| Verts | The number of vertices that the frame mesh contains. |
| Faces | The number of triangles that the frame mesh contains. |
| Size | The file size of frame mesh. |
| Total | The total file size of all meshes for the frame. |
The simulator will run dozens of different types of simulation calculations during a frame. These different calculations are timed and categorized into a few simulation stages.
| Mesh Generation | Generate simulation output meshes and data. |
| Velocity Advection | Compute the initial velocity field of the simulation. |
| Fluid Particles | Update fluid particle velocities and attributes, and move fluid particles through the velocity field. |
| Pressure Solver | Solve for pressure and adjust the velocity field for incompressible fluid. |
| Whitewater Solver | Simulate whitewater particles and whitewater particle generation. |
| Viscosity Solver | Solve and adjust the velocity field according to fluid viscosity. |
| Simulation Objects | Update fluid objects, inflows, outflows, and obstacles. |
| Other | All other simulation computations not listed above. This category includes, but is not limited to: surface tension calculations, particle sheeting, solid boundary and boundary correction handling, and curvature calculations. |
The simulation cache will store mesh data and other types of data that will be loaded into Blender.
| Surface | Final quality fluid surface mesh. |
| Preview | Preview quality fluid surface mesh. |
| Velocity | Surface velocity attributes. |
| Speed | Surface speed attributes. |
| Vorticity | Surface vorticity attributes. |
| Age | Surface age attributes. |
| Color | Surface color attributes. |
| Source ID | Surface source ID attributes. |
| Whitewater | Whitewater vertex mesh for each particle type (foam/bubble/spray/dust). |
| Whitewater Velocity | Whitewater velocity attributes for each particle type (foam/bubble/spray/dust). |
| Whitewater ID | Whitewater ID attributes for each particle type (foam/bubble/spray/dust). |
| Whitewater Lifetime | Whitewater lifetime attributes for each particle type (foam/bubble/spray/dust). |
| Particles | Fluid particles and fluid particle debug info. |
| Obstacle | Solid obstacles and solid obstacle debug info. |